Petrologic and stratigraphic relationships among middle Ordovician limestones from central Kentucky to central Tennessee

PDF

Download

Open document

Flip pages

Download a page range

Download transcript

Copy asset link

Request this asset

Transcript (if available)

Content PETROLOGIC AND STRATIGRAPHIC RELATIONSHIPS AMONG MIDDLE ORDOVICIAN LIMESTONES FROM CENTRAL KENTUCKY TO CENTRAL TENNESSEE by Peter Edward Borella A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (Geological Sciences) August 1975 UMI Number: DP28535 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI DP28535 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code uest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 DEDICATION To Ginger, wh.o instilled in me an interest in Geology. UNIVERSITY OF SOUTHERN CALIFORNIA THE GRADUATE SCHOOL UNIVERSITY PARK LOS ANGELES, CALIFORNIA 90007 This dissertation, w ritten by Peter Edward Borella under the direction of h .L ? ... Dissertation Com mittee, and approved by a ll its members, has been presented to and accepted by The Graduate School, in p a rtia l fu lfillm e n t of requirements of the degree of D O C T O R O F P H I L O S O P H Y Dean DISSERTATION COMMITTEE Chairman c\ C l - CONTENTS Page LIST OF ILLUSTRATIONS............................. vi LIST OF TABLES ............................. x ACKNOWLEDGMENTS........... xi ABSTRACT.......................................... xiii INTRODUCTION . . . ............................... 1 Setting •«.•• •••••• 2 Previous works ••••••••• ........... 5 Purpose • • . • « • • • • • • • • • • • • * • 13 PROCEDURES AND RESULTS ........................... 23 Megascopic limestone classification ......... 23 Logging and sampling ..... . . 2k Petrographic analysis •••••••••••• 30 Selection of samples for thin section analysis •« ••••••••••••• 30 Preparation of thin sections........... 33 Analysis ............................... 33 Microphotography...................... 35 Carbonate petrology results .................. 35 Class 1 .................................... 35 Page Megascopic description * 35 Microscopic description ............. 36 Subclass 1-1 • •••••••••• 45 Megascopic description Microscopic description Applicable names Subclass 1-2 • ••••••.••. 54 Megascopic description Microscopic description Applicable names Environment of deposition of subclass 1-1 and subclass 1-2 limestones Subclass 1 - 3 ............ 58 Megascopic description Microscopic description Applicable names Environment of deposition Class 2 .......... ........................ 64 Megascopic description ................ 64 Microscopic description • •••••• 64 Applicable names ...................... 68 Environment of deposition ...... 68 Class 3 • •••• ••• .................• • 69 Megascopic description • ............. 69 Microscopic description ............. 72 Applicable names ..... .... 74 Environment of deposition............. 74 iii Page Glass k ............................. 75 Megascopic description •••••••• 75 Microscopic description •••.•.* 75 Applicable names ••••••••••• 83 Environment of deposition 83 Class 5 .................................... Megascopic description • 8k Microscopic description ........... . 87 Applicable names ••••••••••• 92 Environment of deposition *♦•••• 93 Class 6 ............. 9k Megascopic description ••»••••• 9k Microscopic description ••••••• 97 Applicable names ........... ••••• 100 Environment of deposition •♦•••• 101 Conodont analysis •••••••••••••• 102 Definition of tbe time-stratigraphic interval 103 Statistical procedures ..................... 112 Lithostratigraphy and the sediment deposition model ••••«•••••••• 114 Northern province..................... 115 Tally matrix ........... ....... 115 Lithostratigraphy • ••••••»•• 118 Thickness and lateral extent « • • ♦ • 118 Page Sediment depositional model • ......... 120 Central province *«•••*•••••«• 125 Tally m a t r i x ........... 125 Lithostratigraphy . . . . . . . . . . . 128 Thickness and lateral extent . # • • • 128 Sediment depositional model ••••«• 129 Southern province ......... ........ 130 Tally matrix ..... ... 130 Lithostratigraphy •«••«•»•••• 130 Thickness and lateral extent • . • • # 130 Sediment depositional model ••*••••• 133 Regional paleogeography and sediment depositional model ......................... 135 DISCUSSION.......................................... 138 MODERN DEPOSITIONAL ANALOG ......................... 165 CONCLUDING REMARKS ....... .................. 167 REFERENCES CITED .................................... 171 APPENDICES.......................................... 182 v LIST OF ILLUSTRATIONS Figure Page 1* Index map of study area, core locations and positions of stratigraphic cross- sections .............• •••••••••• 2 2. Schematic columnar section of Lexington Limestone, central Kentucky (after Cress- man and Karklins, 1970) • •••••••• 6 3* Schematic columnar section of Nashville Group, central Tennessee (after Wilson, 1 9 3 5 ) ...................................... 11 4. Class 1 limestones • ••••••••••• 37 5# Class 1 limestones • •••.••••••• ^0 6. Class 1 limestones ..•..••••••• b2 7# Subclass 1-1 limestones............ • • • b6 8. Subclass 1-2 limestones • • 55 9* Subclass 1-3 limestones • •••••••• 59 10. Class 2 limestones ..................... 6 5 11. Class 3 limestones •••••••••••• 70 12. Class b limestones........... 76 13* Class b limestones........... 79 14. Class 5 limestones •••••• 85 15* Class 5 limestones.................. 88 Figure Page 16. Class 6 limestones • ••••••••••• 95 17• Class 6 limestones ..•••••••••• 98 18. Results of conodont study core no. CA-179 10^ 19# Comparison chart of the results of this study (CA-179) with the Frankfort, Kentucky and Clays Ferry, Kentucky sections of Sweet, Harper and Zlatkin (197^0 • • • • • 108 20. Stratigraphic cross-sections ••••••• In pocket 21. Ripples located in Clays Ferry Formation northwest of Sadieville, Kentucky .... 122 22. Relative mechanical energy and depth values assigned to each class or subclass of limestones .. .. .••••••••• 139 23* Relative mechanical energy contour map . • 1^2 2k, Relative water depth contour map: Case 1 1kk 25. Relative water depth contour map: Case 2 1k6 26. Isopach contour map of study area .... 152 27* Structural map of the base of the time- stratigraphic interval ••••••••.. 15^ 28. Isometric computer plot of relative mechanical energy contour map ........... 156 29. Isometric computer plot of structural contour map ••••• 158 Appendix Figures 1. Generalized columnar 2. Generalized columnar 3. ■ Generalized columnar 4. Generalized columnar 3. Generalized columnar 6. Generalized columnar 7. Generalized columnar 8. Generalized columnar 9. Generalized columnar 10. Generalized columnar 11. Generalized columnar 12. Generalized columnar 13. Generalized columnar 14. Generalized columnar 15. Generalized columnar 16. Generalized columnar 17. Generalized columnar 18. Generalized columnar 19. Generalized columnar 20. Generalized columnar 21. Generalized columnar 22. Generalized columnar 23. Generalized columnar section of core CA-19 . Page 195 section of core CA-81 . 197 section of core CA-71 . 199 section of core CA-29 . 201 section of core CA-43 . 203 section of core CA-84 . 205 section of core CA-88 . 207 section of core CA—100 209 section of core CA-27 . 211 section of core CA-6l . 213 section of core CA-169 215 section of core CA-179 217 section of core CA—121 219 section of core CA-66 . 221 section of core CA-55 . 223 section of core DU-3 . 225 section of core CA-34 . 227 section of core 152 . . 229 section of core 153 . . 231 section of core 162 . . 233 section of core 161 . . 235 section of core 166 . . 237 section of core 168 . . 239 viii Appendix Figures Page 24. Generalized columnar section of core 170 . . 241 25. Generalized columnar section of core 171 . . 243 26. Generalized columnar section of core 199 . . 245 27. Generalized columnar section of core CA-35 . 247 28. Generalized columnar section of core 157 . . 249 29. Generalized columnar section of core 156 . . 251 30. Generalized columnar section of core 198 . . 253 31. Generalized columnar section of core 196 . . 255 32. Generalized columnar section of core CA-57 . 257 33. Generalized columnar section of core CA-37 . 259 LIST OF TABLES Table Page 1* Lithologic description of units within the Lexington Limestone (after Cressman, 1 9 7 3 ) ................................... 8 2. Megascopic rock classification matrix . . * 25 3* Quantitative summary of observed rock features based on frequency of occurrence in 1,217 core slabs . . ........... 27 4* Distribution of thin sections studied from the Limestone classes 31 5* Tally matrix for north province 116 6. Tally matrix for central province .......... 126 7. Tally matrix for southern province .......... 131 Appendix Tables A. Locations and topographic elevation of diamond drill cores •••••••«•••« 183 B« Distribution of conodont elements in core CA-179................................... 186 C* Values for relative mechanical energy, relative depths, isopach and structural contour maps •« • • • • • • • • • • • • • • 190 x ACKNOWLEDGMENTS The author would like to thank his dissertation advisor, Dr. Robert Osborne, who willingly gave his time, continually offered suggestions, and criticized this investigation. The author is also indebted to Dr. William MacQuown from the University of Kentucky for acquainting him with the study area in Kentucky, guiding field trips to type localities and for serving as his advisor away from home. Earl Cressman and Leonard Alberstadt were also kind enough to guide field trips to selected localities in Kentucky and Tennessee, respectively. Many thanks are ex tended to James Mehegan who assisted in the drafting of figures, Robert Schalla who developed and printed the photomicrographs, and Wayne Borella who assisted in the preparation phase of the Conodont study. Special thanks are extended to Dr. Richard Miller of California State University at Northridge for identifying the conodont species. Virginia Lowe and Mary Borella also assisted in core sampling and babysitting, John MacDonald from the Geography department at the University of Southern Cali fornia kindly made the computer program available which was used in this investigation. I would like to thank Dr. Robert Ebinger and Mr. Peter Price of Cominco American for permitting the use of their cores. The Kentucky Geological Survey, The United States Geological Survey, and The University of Kentucky also made cores available for study. Special thanks is extended to The University of Kentucky for providing funds to ship the cores, space and research facilities, and for Dr. Robert Osborne1s sabbatical leave during the 1972-73 academic year. Lastly, I would like to thank Ginger, who served as my field assistant, laboratory assistant, and typist and who kept encouragement and laughter high during all phases of the study. ABSTRACT Biogenic limestones and calcareous shales exposed in areas around Lexington, Kentucky and Nashville, Tennes see can be traced and correlated to each other in the sub surface by systematic analysis of a series of diamond drill cores. Detailed megascopic and microscopic examina tion of these rocks showed that they may be categorized into six major limestone classes, each of which reflects a different depositional environment. A time-stratigraphic interval is defined within this study area. The base of this interval is defined by the presence of a bentonite bed which commonly occurs approx imately 200 feet above the top of the Tyrone Limestone. The upper limit of the time-stratigraphic interval is de fined by the relative abundances of deep—to—shallow-water platform conodonts, represented by Phragmodus and Plecto— dina, respectively. Bentonite beds are present in some areas where fluctuations in the relative abundances of the conodont elements are also observed. This suggests that these fluctuations represent an isochronous or nearly isochronous surface. Detailed logging and resultant stratigraphic correla tions among the cores suggest that changes observed on xiii a microfacies level are reflected on a regional scale. Relative mechanical energy and relative depth indexes, based on microfacies measurements, were constructed to infer the paleobathymetry and paleoenvironment which existed in the area during the defined time-stratigraphic interval. Relative mechanical energy and depth contours intersect the present-day Cincinnati arch axis at very high angles. This suggests that paleobathymetry was not influenced by the Cincinnati arch during this time. Shoal environments existed in the area around Lexington, Kentucky and in the south, north-northeast of the present-day Nashville dome. The Lexington shoal was surrounded by deeper water environments on the north, east and south and suggests that the Lexington dome or a precursor to the dome was present at this time. Paleo- bathymetric contours roughly parallel east-west and north- south trending normal faults which are present in the Lexington area. This suggests that these faults were active during middle Ordovician time and that movement along these faults may be responsible for creating the bathymetric relief necessary for shallow water mechanical ly agitated sediments to accumulate. Deeper water environments occurred to the north, west and east of the southern shoal area, with a more re— xiv stricted environment to the south. This restricted environment along with the relative decrease in water depths as one approaches the Nashville dome area suggests that the Nashville dome or some submarine expression of what was to become the Nashville dome may also have been present during this time. xv INTRODUCTION Setting The inner Blue Grass region of Kentucky through the north central area of Tennessee (Fig. l) is partially underlain by biogenic limestones and calcareous shales of late Middle and early Late Ordovician age. The rocks are assigned to the Lexington Limestone and Clays Ferry Forma tions in Kentucky and the Bigby—Cannon and Catheys Forma tions in Tennessee. These limestones and calcareous shales are brought to the surface in limited exposures in the areas around Lexington, Kentucky and Nashville, Tennessee by two geologic structures, the Jessamine (Lexington) dome in the north and the Nashville dome in the south. Coincidentally through the centers of these domes runs the axis of the Cincinnati arch (Fig. l). The Jessamine dome is broad, irregular and gentle with beds dipping generally 20 to 30 feet per mile west ward and somewhat less northward (Cressman, 1973)* Two major normal fault systems, the West Hickman-Bryan Station fault zone and the Kentucky River fault zone transect the dome (Fig. l). The Kentucky River fault system and the 1 Figure 1 Index map of the study area, core locations and positions of strati- graphic cross sections. 2 Cumberland '/S addle 3 proximal Irvine-Paint Creek fault zone extend to basement rock (Bayley and Muehlberger, 1968) and were active in Cambrian time (McGuire and Howell, 1963; Webb, 1969)* Wilson (1935) describes the Nashville dome as a large anticlinal structure that forms the southern end of the Cincinnati arch and occupies all of central Tennessee. The highest point on the dome lying along the axis of the Cincinnati arch is located in south central Rutherford County. From this point the axis of the dome dips about 8 feet per mile both to the southwest and northeast. The average dip on the flanks of the dome (northwest and south east) averages approximately 16 feet per mile. Faulting on the Nashville dome is not very common but small normal faults occur (Wilson, 1935)• They are usually only a few miles long and have vertical displace ments with a maximum of 300 feet but more commonly closer to 30 feet. Separating the Jessamine dome and the Nashville dome is a structural saddle (Cumberland Saddle) which trends almost normal to the axis of the Cincinnati arch. Xn this saddle the Chattanooga Shale (Devonian) is topo graphically 700 feet lower than on the crest of the Nash ville Dome (Wilson, 1935)* k Previous Works Xn Kentucky, recent work by the United States Geological Survey, The Kentucky Geological Survey, and The University of Kentucky has resulted in constructing a workable lithologic framework regarding the major lith- ologies within the Lexington Limestone and Clays Ferry Formations (Fig. 2, Table l). Recent publications result ing from this work include Black, Cressman and MacQuown (1965)* Black and MacQuown (1965)» Cressman and Karklins (1970)9 MacQuown (1967)* Weir and Green (1965)* Hrabar, Cressman, and Potter (l97l)> Mackey (l972), Etter (personal communication), and a series of U. S. Geological survey quadrangle maps included in the list of references. Cress man (1973) presents a comprehensive summary of the Lexing ton Limestone and superadjacent Clays Ferry (Point Pleasant) Formations based mostly on the detailed mapping of twenty—three 7ir minute quadrangles supplemented by diamond drill cores and measured stratigraphic sections. The pioneer work on the stratigraphy and geologic history of the Middle and late Middle Ordovician in central Tennessee was done by Wilson (1935, 19^9* 1962). Xn these works Wilson defines and divides the Nashville Group into three formations: the Hermitage, Bigby-Cannon and Catheys (Fig. 3)• The limestone facies found within 5 Figure 2. Schematic columnar section of Lexington Limestone, Central Kentucky (after Cressman and Karklins, 1970). 6 < o > o Q QC O LlI I- < o a> “ O c o LU _ l O o a> o CLAYS FERRY FO R M ATIO N L lI Z o I — CO LU O I — CD Z X LU Tanglewood Limestone Millersburg Member * Member Devils Hollow Member Sulphur Well Member i Brannon Mem ber Perryville Limestone Member Grier Limestone Member Macedonia Logana Member Curdsville Limestone Member Tyrone Limestone LU CD a c c cl m => o x cn CD CD X Oregon Formation 7 Table 1 Lithologic description of* units within the Lexington Limestone (after Cressman, 1973)* 8 Lithologic Unit Thickness (feet) Dominant Lithology Lexington Limestone Tanglevood Lime stone Member 0—100 Bioclastic calcarenite and biosparite with rounded allochems Millersburg Member 0-90 Devils Hollow Member 0-30 Nodular, fossiliferous calcilutite and calci- siltite with beds of biosparite and bio- sparrudite Biosparrudite overlain by calcilutite with interbedded minor shale Sulphur Well Member 0—35 Brannon Member 0-30 Poorly-sorted bryozoan calcirudite separated by shale partings Interbedded calcisil- tite and shale in nearly equal propor tions Perryville Limestone Member 15 Macedonia Bed Grier Limestone Member 0-15 100-180 Calcilutite and calci- siltite with some shale partings Argillaceous calci- siltite interbedded with 10-^0c / o shale Fossiliferous calci- siltite and poorly- sorted calcarenite separated by shale partings 9 Lithologic Unit Thickness (feet) Dominant Lithology Lexington Limestone (continued) Logana Member O i0 1 o Xnterbedded calci- siltite and shale in nearly equal propor tions Curdsville Lime stone Member 0 - 3 - 1 o c \ t Bioclastic calcarenite; several thin bento nites 10 Figure 3 Schematic columnar section of* Nashville group, central Tenes see (after Wilson, 1935). 11 37* o LU CATHEYS Fm. < o _1 _1 > BIGBY-CANNON Fm o Q a: X CO < z HERMITAGE Fm w LU — 1 Q STONES RIVER Gr. O 2 12 tliese formations are classified megascopically into four types (¥ilson, 1962): (l) laminated argillaceous lime stones, (2) granular ph.osph.atic limestone, (3) dove- colored limestone, and (4) "normal" eastern limestone with varying quantities of silt. Normal eastern limestone in cludes a shaley facies, laminated siltstone facies and the nodular facies of Wilson (19^9)* Alberstadt (1973) has contributed significantly to the understanding of the depositional environments and origins of the fine-grained limestones referred to as "Dove” within the Bigby—Cannon Formation, Purpose The purpose of this study is to help resolve five geologic problems which exist in the area. These are: recognition, definition and classification of carbonate microfacies present; lithostratigraphic correlation of the measured cores; recognition of one or more isochronous or nearly isochronous surfaces within the observed strati- graphic interval; environmental interpretation of the carbonate facies; and relationship of the above to the late-middle and early—Late Ordovician history of the Cin cinnati arch system. Each topic will be discussed in the following sections. 13 Recognition, definition and classification of carbonate microfacies To date no systematic or detailed petrographic analysis has been performed within the upper Lexington Limestone members (Brannon and Younger, Fig# 2), Clays Ferry Formation, upper Bigby-Cannon Formation and Catheys Formation. The abundant and rapidly changing carbonate macrofacies within these formations suggest at least equal if not greater variations at the microfacies level. The availability of subsurface cores provides an excellent opportunity to help define and quantify the microfacies present and to determine their spatial relationships. MacQuown (1967) has studied 200 acetate peels and 430 petrographic thin sections from the Curdsville member of the Lexington Limestone. Cressman (l973)> Mackey (1972) and Etter (personal communication) have supplemented their megascopic descriptions of the major limestone types with thin sections but no detailed systematic petrographic analysis was performed. Alberstadt (1973) has petro— graphically examined the fine-grained limestones in the Bigby—Cannon Limestone of Tennessee. Lithostratigraphic correlation of the measured cores No direct lithologic correlation has been made relating the upper Middle and lower Upper Ordovician lime stones and calcareous clays in Kentucky to those found in 14 Tennessee because of the lack of surface exposures on and between the Jessamine and Nashville domes* The opportunity now exists with the availability of subsurface cores at strategic locations to correlate and trace these lime stones and clay units from the Jessamine dome through the Cumberland Saddle into the Nashville dome area (Fig. l). With detailed lithostratigraphic correlations between cores, lateral and vertical facies changes on a regional scale may be postulated and tested against those interpre tations of Wilson (1962), Cressman (1973) and others which were performed in the Nashville, Tennessee and Lexington, Kentucky, respectively. Recognition of one or more isochronous or nearly iso chronous surfaces within the limestones The need to identify as many isochronous surfaces as possible within the limestone and clayey units in the study area has been pointed out by Cressman (1973)* His paleo graphic and facies relationships are somewhat subjective because the Lexington Limestone and its equivalents have not been zoned with respect to time. Conodont biostratigraphy may help resolve this problem. Conodonts were pelagic marine organisms that were numerous and widespread during Paleozoic and Mesozoic seas. They do not appear to be lithologically controlled and are extensively used for biostratigraphic zonations and correla 15 tions (Sweet and Bergstrom, 197l)* More importantly Ordovician conodonts were exceptionally diverse, are well known and have been used effectively in local and regional correlations (Bergstrom, 1971; Ethington and Clark, 1971; Lindstrom, 197l)* Bergstrom and Sweet (1966) and Sweet, Harper and Zlatkin (197^) have examined conodonts from the Lexington Limestone and its lateral equivalents in Kentucky, Ohio and Indiana# By plotting the relative abundance of Phragmodus with respect to Plectodina several distinct peaks have been obtained# It has been suggested that lateral and vertical fluctuations in the relative abundance of these genera are directly related to variations in water depth (Seddon and Sweet, 197l)• 3n relatively shallow water deposits, Plectodina is dominant and Phragmodus is rare or absent# In relatively deeper water deposits, Phragmodus is abundant with Plectodina also common to abundant# This relationship suggests that Plectodina in habited a biozone much closer to the surface than did Phragmodus# Hence Plectodina could accumulate on the bottom in both shallow and deep water environments, where as Phragmodus would be restricted to the relatively deeper water areas# It is the purpose of this phase of the project to examine a core in southern Kentucky (Ca-179* Fig* l) for conodont elements and attempt to correlate the obtained 16 results with the works mentioned above* Isochronous sur faces may be defined throughout the study area by fluctua tions in water levels which are reflected in relative abundances of conodont genera* Environmental interpretation of the carbonate facies The data obtained from the megascopic and micro scopic analysis along with the primary sedimentary struc tures observed within the diamond drill cores and outcrops, the subsurface stratigraphy and the biostratigraphic evidences will be used to interpret the most probable en vironment of deposition for each microfacies. Studies on Holocene carbonate sedimentation (e.g., Newell and Rigby, 1957? Ginsburg, 1957; Deffeyes, jet al., 1963; Shinn, et al., 1965; Tiling, e j f c al., 1965; and Logan, et al., 1970) have provided useful criteria for the recognition and delineation of modern supratidal and inter tidal depositional environments. Shinn (1968), Laporte (1969)* Braun and Friedman (1969) and Young, et al. (l972) to name a few, have applied these criteria in interpreting ancient carbonate environments. Excellent summaries of these criteria are given by Rigby and Hamblin (l972) and Young, et al. (l972)* To help interpret the paleo-environment which exist ed in the chosen area, relative mechanical conditions and water depths present at the depositional sites for the various macrofacies and microfacies will be postulated and tested, Osborne (1973) has shown that an analysis of the areal frequency of several limestone classes yielded meaningful results in interpreting depositional environ ments and energy conditions within the Kope and Fairview Formations (Upper Ordovician) in Hamilton County, Ohio, A modification of this method will be used to attempt to delineate paleogeographic provinces which may be recog nized and separated on the basis of relative mechanical energy and water depth conditions which were present at the sediment depositional sites. Some previous primary sedimentary structures will be used to help define current directions and the presence of shoals and banks. Hrabar, Cressman and Potter (l97l)» working in the Tanglewood Member of the Lexington Lime stone, have postulated a bimodal crossbed orientation with modes 180° apart. The modes tend to be perpendicular to icopachs which delineate a north-northwesterly trending body and are interpreted as being tidal in nature. Addi tional information from primary sedimentary structures in other members and formations may yield meaningful results. Relationship of the above to the upper Middle and lower Upper Ordovician history of the Cincinnati arch Controversy still exists concerning the geologic history of the Cincinnati arch in the Ohio, Kentucky and Tennessee areas. A brief summary of the development of ideas behind the arch genesis follows, Xn the area around Cincinnati, Ohio most workers place the age of the Cincinnati arch at no earlier than Silurian (Newberry, 1873; Orton, 1888; Guststadt, 1958; Scotford, 1964, 1965; Guari, Noland, Moore, 1969)# How ever, Locke (1838) considered the arch was uplifted in Ordovician time, Weiss and Sweet (1961) suggest the existence of a shallow water, high energy environment in the Ohio-Kentucky-Indiana region near Cincinnati through most of the post—Tyrone Ordovician, This shoal appears to be bounded on the north and west by deeper water lower energy environments. Whether this shoal is a result of arching is questionable, but Osborne (1973) has demonstrat ed in the Cincinnati area shoaling during Kope sedimenta tion and minor shoaling during Fairview sedimentation. An interesting fact about this work is that the Kope shoal trends north-northeast, which is at a high angle to the present axis of the Cincinnati arch and suggests that no arch was present. Contrary to this, the minor Fairview shoals trend northwest, are parallel to the arch axis in southwestern Ohio and suggest possible structural control of shoaling, Xn Kentucky and Tennessee past and present workers are still divided in their interpretation as to whether an arch or dome was present in Ordovician time. Supporting an Ordovician arch are Hayes and Ulrich (1903) and MacQuown 19 (1967) who recognize carbonate shoals in the basal Lexing ton Limestone Member on the Lexington dome; and Mackey (1972) who suggests arch shoal facies and adjacent basin facies in southern Kentucky. Opposed to an Ordovician arch are Cressman (l973)» who cites east-west depositional strike of some members of the Lexington Limestone as evi dence against the presence of an arch and Wolcott, Cress man and Connors (l97l) who propose a similar depositional strike of the High Bridge Group which underlies the Lexing ton Limestone. Hrabar, Cressman and Potter (l97l) recog nize the presence of a carbonate shoal along the projecting westward during the deposition of the crossbedded Tangle- wood Limestone Member of the Lexington Limestone. They do not postulate the presence or absence of an arch. McFarlan (1943) recognized two main periods of development of the Lexington dome, the first in pre—middle Devonian and the second in Permian. Raymond (1922) proposed shoaling and the presence of reefs in central Tennessee in the arch area in the Middle Ordovician. Wilson (1935) places the initial uplift of the Nashville dome in the Ordovician and Wilson (1962) further reports shallow marine facies and periods of sub- aerial exposure on the dome at this time. Contrary to this Freeman (l95l) suggested arching took place during the Silurian in central Tennessee but also, Freeman (l9^9> 195l) stated that some submarine topography in the arch 20 area was present in Middle Ordovician time, Xt becomes apparent that some of these differences of opinion can be resolved realizing that arch genesis is complex and the arch structure took different shapes at different times in different areas. The vast majority of the workers in the Cincinnati-Ohio region agree that there is little or no evidence for an arch in Ordovician time. The presence of an Ordovician arch structure in Kentucky and Tennessee is possible and may be explained by one or a combination of the following. (l) A north-south fault zone extending to basement rock, Grenville raetamorphics (McGuire and Howell, 1963; Watkins, 1962, 1963* 1964) is reflected at the surface by the north-south trending Little Hickman and Bryant Station fault of the Kentucky River Fault System (Fig, l). Basement displacements of 2300 feet have been documented along these fault systems in Kentucky and northern Tennessee (MacQuown, personal communication). At least 2000 feet of movement occurred during the deposition of the Early Cambrian basal con glomerate (Potsdam Megagroup) which is mostly absent on the Lexington dome and 2000 feet thick on the downdropped block to the east (Bond, 197l). This Cambrian growth fault might be the earliest expression of a proto—Cincin nati arch. The parallel structural features may be re sponsible for the development of the Lexington dome, 21 Cumberland Saddle, Nashville dome and any transecting arch channels which could produce an east-west lineation in some facies. (2) It is possible that movement along the arch during the Ordovician progressed from a south to north direction. Movement on the arch was more positive in the south (Nashville dome area), neutral to the north (toward the Jessamine dome) and in southern Ohio. (3) Structural relief on the arch may be related to sub sidence of adjacent basins, which may have produced the topographic highs necessary for the accumulation of shallow water facies. (U) Lastly, the arch structure may have been only slightly submergent or emergent during certain times and provided a physical barrier to continuous sedimenta tion or a transition zone to continuously submerged areas. This may be the result of isostatic adjustment of basement rock, global tectonics (Bird and Dewey, 1970) or eustatic sea level changes. It is hoped that a workable depositional model or models can be constructed from the available petrologic, stratigraphic and environmental evidence. From such a model the Middle Ordovician history of the Cincinnati arch in the study area may be inferred. 22 PROCEDURES AND RESULTS Megascopic Limestone Classification A megascopic classification of limestone litliologies was erected in order to log and correlate the various cores which, were made available from the United States Geological Survey, the Kentucky Geological Survey and Cominco Oil Company. The core locations, depths of pene tration, sampling interval and topographic elevation are given in Table A of the appendix. Limestone units were first observed and examined in the field. Samples at each outcrop were taken and cate gorized. The megascopic criteria used were grain size, megascopic fossils, intraclasts, color, bedding, sedi mentary structures and a coarse to fine grain-size ratio. This is a modification of the classification system used by MacQuown (19&7) in the lower members of the Lexington Limestone Formation. Secondly, a base core CA-121 was logged at one foot intervals using the same criteria. Cor relation and refinement between the field samples and the base core followed. The resulting six classes and three subclasses of limestones and the sedimentary character— 23 istics used to distinguish, them are given in Table 2. An additional 1,217 polished and wet core slabs were examined for similar and additional information. The additional features which became more apparent in polished sections and proved useful were cross bedding- and cross laminations, parallel laminations, mottling effects and burrowing, algal laminations, birdseye texture, stomatoporoids, stylolites and vugs. Table 3 is a quantitative summary of the various features based on frequency of occurrence within the ex amined core slabs. Correlation between the preliminary classification and the rock slabs was excellent which showed the classification was serviceable without further modification. above classification and based on one foot intervals. An additional 1k cores were similarly constructed using five foot intervals. Each foot or five foot interval was broken down into major and minor lithologies. The percentage of graphed along with any obvious or noticeable sedimentary structure or diagenetic feature. The cores are stored in the Sedimentary Petrology Laboratory, Science Hall, Univer sity of Southern California. Simplified versions for each core are given in the appendix. Logging and Sampling Continuous logs of 19 cores were made using the fine-grained material (less was recorded and 2k Table 2. Megascopic rock classification matrix. MEGASCOPIC LIMESTONE CLASSIFICATION MATRIX Limestone Field and Hand Specimen Characteristics Class or Subclass Grain size Color* Bedding Coarse to fine ratio Intraclasts Mega fossils 1-1 coarse^ 1 mm light planar .2 to 1 foot » i common to rare (257. to < 107.) abundant > 25 7. 1-2 medium 0.25 - 1,0 mm light planar .2 to 1 foot >>l common to rare (257. to <107.) abundant > 257 . 1-3 fine .062 mm- .250 mm light planar .2 to .3 foot > i common to rare (257. to< 107.) abundant > 257 . 2 very fine ^ .004 mm- .062 mm dark planar .2 to 1,0 foot <<i rare ( < 107.) rare (< 107.) 3 coarse 1 nan inter mediate irregular to nodular 1 foot thick >i rare (< 107.) abundant > 257 . 4 coarse to fine^ 1 mm to ^ .004 mm inter mediate irregular, rubbly to nodular 1 to 2 feet thick 11 common (107. - 257.) common (107. - 257.) 5 very fine ^.004 mm light planar 3 in. to ^ I foot thick « i rare to absent «107.) common (107. - 257.) 6 coarse to fine 1 mm to K .004 mm inter mediate to dark rubbly to nodular .5 foot thick s 1 common (107. - 257.) common (107. - 257.) * Terms appearing in table are used to indicate conditions relative to the other classes of limestones ro For exact colors (G.S.A. rock color chart), see carbonate petrology results, ON Table 3 Quantitative summary of observed rock features based on frequency of occurrence in 1,217 core slabs Sedimentary Structures From logs and polished rock slabs Total number of samples - 1«217 rock slabs Limestone Class and Subclass Sedimentary 1 2 3 k 5 6 Structure 1-1 1-2 1-3 Burrowing mottling 5 8 26 15 1 5 ks 12 Cross bedding cross laminations k 21 35 10 0 1 1 Vugs 11 15 1 5 1 Stylolites 2k 55 10 k 1 1 Microfaults l 1 Intraclasts mudchips 80 5k 53 50 11 171 7 29 Stromatoporoid 0 10 8 7 1 3 3 Birdseye 2 26 7 Algal mounds laminations 1 1 1 11 r o oo Sedimentary Structures (continued) From logs and polished rock slabs Total number of samples - 1,217 rock slabs Limestone Class and Subclass________ Sedimentary 1 2 3 4 5 Structure 1-1______ 1-2_____1-3 Fine laminations 4 35 80 48 1 5 Bioclasts 164 165 47 25 13 136 20 16 Calcite crystals 14 4 1 1 9 Flame structure 1 1 Ripples 1 Mud dessication cracks Flaser bedding 1 Scour marks 1 1 ro vo Within each core, samples were taken at five foot intervals. Sampling procedures consisted of cutting a 4 to 6 inch section out of the core and sawing it longi tudinally. One-half of the sample was returned to the core box, the other half was labeled and bagged. The cores are stored at the Kentucky Geological Survey Core Library and Bowman Hall, University of Kentucky. The sample halves are stored at the Sedimentary Petrology Laboratory, Univer sity of Southern California. Petrographic Analysis Selection of Samples for Thin Section Analysis Samples were chosen throughout the whole study area within the desired stratigraphic interval in order to ob serve maximum variations in microfacies. Examination of Table 4 indicates that the majority of the thin sections are categorized megascopically into Classes 1 and 4. Also along with the Class 2 limestones they are the major lithologies which appear in the stratigraphic interval studied. Only six thin sections of Class 2 were examined petrographically, because megascopic examination of such rocks revealed a very fine-grained texture and a monoton ously consistent appearance. Examination of these clay- sized rocks with a polarizing microscope under high power is extremely difficult and does not appear to significant ly improve on the environmental interpretation. Classes 30 Table h Distribution of tliin sections ex amined from the limestone classes. Thin Section Distribution Limestone Class or Subclass _________1____________ 2 3_____ 4______£_____ £ 1-1 1—2 1-3 Number of thin sections examined 23 22 16 6 3 30 12 10 Total number - 124 32 3, 3 and 6 rock types are minor in occurrence within the chosen interval and are most commonly found in the strata immediately beneath the stratigraphic interval of interest or in the basal sections of the cores* They are, however, highly significant and valuable in understanding and interpreting lateral and vertical facies changes, de- positional environments and the overall structural and sedimentological conditions which existed during the chosen time-stratigraphic interval. Preparation of Thin Sections Petrographic thin sections were commercially pre pared from 124 of the core samples. Rock thin sections were cut perpendicular to bedding. One-third to one-half of the thin section area was stained with alizarin red following the procedure outline by Friedman (1959)* Thin sections remained uncovered so that they could be analyzed by cathodoluminescent techniques. Analysis Examination of rock thin sections was done using a Leitz Dialux—Pol research polarizing microscope and a Cathode-ray Luminoscope. The initial step in the microscopic analysis was to construct a check list and data sheet. Major headings in cluded orthochemical constituents, allochemical grains, 33 textural analysis, diagenesis, rock name, environment of deposition, energy conditions at the deposition site, photomicrographs and drawings, and the summary. A pre liminary investigation of the petrographic thin sections revealed that diagenetic effects had severely altered and obliterated the allochemical constituents, matrix and cements which existed within the limestones. Because of this a modal analysis (point counts) was not performed on the thin sections. Estimates of percentages of ortho- c hemical and allochemical constituents were made visually with the aid of diagrams presented in Terry and Chillinger (l955)* Dolomite percentages were estimated from the stained portion of the thin sections. Allochemical grains were identified and classed as being abundant 25 percent), common (10-25 percent), rare (10 percent), or absent (not observed). Grain size measurements were made with an ocular micrometer. Maximum and minimum grain sizes were determined by scanning the entire thin section. Grain measurements, except for the rudite grain sizes, were made under medium power lens (lOX). Sorting among allochems was determined on the basis of the range in grain sizes and with the aid of diagrams given in Folk (1965)* Examination of thin sections under the Cathode Luminoscope was done in order to help decipher the dia genetic history, determine trace element components and determine the origin of the dolomite which existed within the thin sections* The classification systems of Folk (1959) and Dunham (1962) were used to determine rock name s• Microphotography Microphotographs of the various classes and sub classes of limestones were taken using a Zeiss Xkon 35 nmi camera and light meter attached to the research polarizing microscope and the Cathode luminoscope. Color slides were taken using Kodachrome and Ektachrome film (135-36)* High speed Ektachrome (ASA 165) was used for photographs which were taken under the luminoscope. Black and white prints were taken from the slides. Carbonate Petrology Results The salient features of each class of limestone are described below. Colors are identified with reference to the G.S.A. Rock color chart (1970). The systems of Folk (1959) and Dunham (1962) are used to classify limestone types. Class 1 Megascopic description Megascopically rock assigned to this class range in color from a light—pinkish-gray (5YR8/1), light-gray (N7), 35 light-olive-gray (5Y6/1) to olive-gray (5Y4/l). Rock names based on grain size are calcisiltites to calcirudites with, the most common rocks being calcarenites (Table 2). Possil fragments are the most abundant allochemical con stituent* Intraclasts, which include carbonate mud chips, appear to a lesser extent (Table 2)* Sorting among allochemical grains ranges from poor to a moderately well condition. Common sedimentary structures include in de creasing abundance (Table 3)» fine horizontal laminations (less than 1 cm), cross laminations, small scale cross bedding and mottling effects produced either by burrowers or by the weight of overlying sediments which temporarily produced a liquified sediment. Noticeable diagenetic features include stylolites and large vugs which may or may not be filled with calcite crystals. Insoluble materials are less than 10 percent by weight. Stratifica tion (^1 cm) is generally planar (Fig. 4a)• Megascopically class 1 lithologies can be divided into three distinct subclasses. Microscopic description Although each subclass will be discussed in the following sections, it is convenient to discuss those petrographic characteristics which are common to class 1 limestones. Class 1 limestones have undergone severe diagenetic 36 Figure 4, Class 1 limestones A, Example of planar bedding in class 1 limestones interbedded with class 2 limestones* Lincoln Quappe point ing to contact between Tanglewood Limestone Member and Brannon Member of Lexington Limestone Formation* B. a. Neomorphic pseudospar* Notice dusty appearance and lack of enfacial angles. b. Allochemical ghost structure* C. a. Ghost structure of fossil (Pelmatozoan?) grain. D. a. Pelmatozoan grain. b* Neomorphic sparite transecting fossil grain boundary. c. Dusty sparite suggestive of neomorphism with micritic interstices. d. Micrite and opaque materials interspersed with pseudospar. 37 alteration. Because of this, a major problem arises in interpreting the depositional environment which existed where sediments accumulated to form the limestones. This diagenetic alteration (neomorphism) is most evident within the orthochemical constituents of the thin sections ex amined. The vast majority of the most abundant orthochem, sparry calcite is neomorphic in character. Pseudospar is dominant ranging in sizes from 30 p. to hO p. to greater than 20 mm (Fig. 4b). Microspar is also very common with sizes averaging between h ja to 30 yu. Evidence for the neo morphic character of these rocks is supported by numerous allochemical ghost structures (Fig. Uc), sparite transect ing allochem grain boundaries (Fig. 40), recrystallized allochems (Fig. 5A), syntaxial overgrowths on transported pelmatozoan fragments (Fig. 5B), micritic patches floating in sparite, few enfacial triple junctions, and the general overall dusty appearance of the sparite examined in the thin sections. However, it does appear in thin sections that a majority of the limestones are grain supported. Embayed grains and overly close packing among allochems (Fig. 5C, D) are common. Furthermore, the presence of transported and abraded grains (Fig. 6) and the overall abundance of fossil allochems (Fig. 6) within the thin sections support this supposition. Cross beds and cross laminations are observed in the field and in hand specimen, which clearly 39 Figure 5* Class 1 limestones A. a. Recrystallized allochems, mollusk fragment. b. Micrite interstice. c. Brachiopod fragment. d. Neoiaorphic calcite. Note micritic patch in sparry cal cite. B. a. Phosphate infilling a bryozoan zooecia. b. Pelmatozoan fragment. c. Syntaxial overgrowth on pel matozoan fragment. C. a. Example of embayed grain contact between two large brachiopod fragments — supporting grain support fabric hypothesis, b. Opaque and insoluble materials filling in intergrain area. D. a. Example of overly close packing between two large brachiopod fragments, supporting grain support fabric hypothesis, b. Neomorphic calcite (pseudospar) eating into micrite patch. ^+0 0 .5 m m kl Figure 6. Class 1 limestones# A# a. Rounded and transported allo- cliemical grains. The following sequence of events is suggested for this grain. Bryozoan frag ment was abraded with micrite later filling in void areas. The micrite and bryozoan (now an intraclast) was then retrans ported, rounded and redeposited. b. Neomorphic calcite, notice micritic patches. c. Large bryozoan grain with includ ed neomorphic calcite. B. Example of abundance of fossil allo chems in class 1 limestones. a. Phosphate infilling in a frag mented bryozoa zooecia. b. Allochem ghost probably a tri- lobite. c. Bryozoan fragment. d. Phosphatized pelmatozoan grain. Notice the embayed grain contact between bryozoan and pelmatozoan grain. C. Rudite size fossil grains and intra clasts. a. Rounded micritic intraclast with included dolomite rhombohedra. b. Abraded bryozoan. D. Dolomitized calcirudite. a. Secondary dolomite transecting allochem boundary. b. Brachiopod fragment. c. Intergrown dolomite rhombohedra. 42 lulu g o indicates currents were active at tlie deposition site where sediments accumulated to form this class of limestones. Grain-supported sediment is typically found in relatively mechanically agitated environments (Dunham, 1962). Ac companying this dominately grain—supported fabric is pseudospar located within and between grains. Was the original intergrain area composed of pore filling cement? Some pore filling calcite is observed but this occurrence is far from conclusive. A more likely explanation is that the original matrix was lime mud which has been sub sequently neomorphosed to produce the observed pseudospar texture. Micritic ghosts, coated grains, micrite inter stices and the overall dusty nature of the pseudospar sup port this conclusion. It thus appears that the original sediment was deposited in agitated conditions and was grain supported. Subsequent to this micrite filled in the void areas and was later neomorphosed. Dolomite is ubiquitous throughout all of the thin sections of class 1 rocks examined. It varies in abundance from 5 percent to greater than 50 percent of the orthochemical constituents with the average being approxi mately 25 percent. The dolomite is usually 30^. to 80 px in size. It is almost always rhombohedral in outline and found commonly in patches, associated with stylolites and veins and with the fine-grained materials. Excellent ex amples of dolomite rhombohedra transecting grain boundaries hh are observed (Fig, 6b), Observation with the luminoscope revealed that virtually all of the dolomite is zoned with many grains showing intergrown boundaries. The nuclei of the zoned dolomite are also dolomitic in composition. There are no associated detrital grains of similar size to the dolomite nuclei nor do any nuclei show signs of round ing or transportation. It is concluded that the dolomite is secondary in origin and doubtful that any of the dolo mite is allogenic. The term "dolomitized" should be pre fixed to any of the petrographic rock names assigned to this class. Subclass 1-1 Megascopic description, A coarse-grained light gray (N7) to medium olive gray (5Y5/1), poor to moderately poor sorted fossiliferous calcarenite to calcirudite most typically describes this subclass (Fig, 7)* Fossil frag ments are abundant and extremely large, many exceeding 2 cm. The most noticeable are bryozoan fragments and dis articulated brachiopod valves, Xntraclast are the second most abundant allochemical constituent by occurrence (Table 3)♦ Diagenetic stylolites are present and are usually fill ed with insoluble materials of clay and silt size. Cross beds, cross laminations, horizontal laminations and mottl ing features are present but are less common within this lithology as compared with the other two subclasses, ^5 Figure 7* Subclass 1-1 Calcirudite A. Polished core slabs of subclass 1—1, calcirudites and calcarenites. a. Large fossil shells with micrite located below. This is an ex ample of sheltering effect produced by a grain support fabric. Hand specimens are oriented so that top of photo graph is stratigraphically up. B. a. Micritized and recrystallized fossil fragments, b. Neomorphic sparry calcite with micrite patch. Below letter b is recrystallized allochems. Above b is a large brachiopod grain. C. a. Large trilobite fragments. b. Micritic coating, suggestive of boring organism. c. Micrite. D. Example of compactional effect in subclass 1-1 limestones. a. Broken brachiopod fragment due to compaction after deposition. b. Allochemical ghost. Notice overly close packing between brachiopod fragments and ghost. 46 0.5 m m Microscopic description. Pelmatozoans, brachio- pods, and bryozoa are the most abundant allochemical con stituents. Trilobites, pelecypods, gastropods and ostra- cods are common and sporadically abundant. Fossil allo chemical grains comprise 30 percent to 70 percent of the thin sections by volume. Size range is extreme ranging from less than 0.3 nun to greater than 20 mm with the average above 1 cm, classifying them as rudite size. Sorting within the fossil allochems is on the average poor with an occasional sample displaying fair to moderately well sorting. Most allochemical grains are broken, abraded and some show signs of rounding and transportation (Fig. 6). Some larger brachiopods, pelecypods and gastropods appear whole and continuous. Fossil grains on the average show no preferred orientation. Occasionally alignment of larger fossil grains (brachiopods and pelecypods) oriented parallel to bedding may be observed. Surrounding many of the fossils are micritic envelopes (Fig. 7)» which probably reflect the work of boring organisms, most likely algae (Bathurst, 1966; Margolis and Rex, 1971) but also possibly bacteria and fungi (Perkins and Halsey, 1971)• Xntraclasts are observed only as a minor constituent by volume in the thin sections examined (Fig. 6). They ap pear as rounded micritic intraclasts with distinct boundaries from the surrounding sparry calcite. Within the intraclasts sometimes are smaller fossil fragments and 48 dolomite rhombohedra which are not located in the surround ing matrix. Within the orthochemical constituents pore Tilling calcite cement is present in only minor amounts which may or may not be a direct consequence of the extreme neo morphism which has taken place in these rocks. Xt is present in some void filled areas, as rim cements around allochems which show a saw toothed character and optic axis orientation perpendicular to grain boundaries, as fillings in some veins and possible burrows, and in a few sheltered areas beneath allochems, i.e., umbrella struc tures. Examination of several thin sections with the cathode—ray luminoscope revealed at least two events with in the matrix of the rock. The first episode was one of cementation, apparently containing a masking trace element, most likely iron, cobalt or nickel (Medlin, 1959)* which caused the calcite matrix to be a dark blue to black color instead of the normal orange cathodoluminescence which is due to the presence of divalent manganese (Med lin, 1963). In plain light this same area had a saw toothed appearance and polarized light revealed an optic orientation perpendicular to grain boundaries. Surround ing this dark blue area was calcite of normal orange luminescence. The orange luminescent calcite is neo morphic in character. The most logical explanation for this sequence is that pore filling cement partially filled 49 in void areas between grains. This was followed by the deposition of micrite into the remaining space which has been subsequently neomorphosed. Micrite is a common to abundant constituent within the rock thin sections examined. Xt commonly is found within bryozoa zooecia and gastropod shells. Truncated fossil grains containing micrite which show distinct con tacts between the micritic grains and the surrounding sparry calcite suggest that some micrite has been trans ported to the deposition site along with the allochem (Pig. 6A). In other thin sections the matrix is dominated by micrite. Even in the virtually micritic free thin sec tions the dusty appearance of pseudospar, micritic inter stices encompassed by sparite, and micritic coatings sug gest that micrite may have been more abundant originally. Microcrystalline calcite can be formed by several methods. Calcareous algae (Ginsburg, 1956) and mechanical abrasion of carbonate fragments may furnish micrite to the sediment (Swinchatt, 1965; Matthews, 1966). Biologically, breakdown by boring organisms (Bathurst, 1966; Element and Toomey, 1967) and disintegration of skeletal fragments caused by decaying organic binders (Lowenstam, 1955; Purdy, 1963) may also contribute to the micrite population within a rock. Inorganic precipitation of lime mud is also a possible source (Smith, 19^0). Because evidence suggests that currents were active at the depositional site of this 50 facies, i.e., megascopic cross beds and cross laminations, transported and abraded allochemical grains, and tbat micritic coatings were commonly observed on skeletal frag ments, micrite may liave formed as a result of both mechani cal abrasion or transportation and by the breakdown by biological organisms. The majority of the micritic rocks which are minor in subclass 1—1 are classified as packestones (Dunham, 1962), Rocks of this nature are described as being grain- supported with a mud matrix. The presence of a carbonate mud matrix is generally a characteristic of sediment deposited in mechanically quiet waters whereas grain sup port is generally a property of sediment deposited in more mechanically agitated waters (Dunham, 1962), Because of this peculiar rock fabric, special attention must be given to determine the energy conditions at the depositional site. Was the original sediment grain supported? Was the mud the result of later infiltration of lime mud between a grain supported fabric, mixing by burrowers of partial washing of mud due to insufficient currents, or was there an abundance of fossil grains produced in quiet water? Baffling or trapping of lime mud by algae, bryozoa, crinoids or other fauna may have also produced such a fabric. Another possibility is that the rock was originally a wackestone and compaction produced the apparent grain- supported fabric. Dunham (1962) has discussed these pos- 51 sibilities and suggests tliat features observed in grain— stones, i.e., floored interstices, embayed grain contacts, overly close packing and skeltered areas be used to deter mine whether tbe original rock was matrix or grain sup ported. Thin section examination of these packestones re vealed no positive grain—supported features. This suggests that the original sediment was matrix supported. Excellent compactional features are observed such as broken fossil fragments lying proximal to one another that when placed back together reveal one continuous fossil grain (Fig. 7D). Patchy distributed mud was noted in several thin sections. This may have been the work of burrowers or minor currents acting in the area. Unlike the majority of subclass 1—1 rocks which predominately are grain-supported and suggest agitated waters at the deposition site, the sediments which comprise the packestones appear to have been deposited in mechanically quieter waters. Phosphate is an abundant accessory mineral. Many of the pores of pelmatozoans, bryozoa zooecia and gastro pods contain phosphatic material. Replacement of many crinoid grains may also be observed. Rounded and abraded arenite-sized phosphatized grains are also observed in laminae and in bedding surfaces. Cressman (1973) states that such a relationship is a clear indication of the work of currents. Supporting this supposition are examples of 52 phosphate being transported in with enclosing fossil frag ments# Truncated, bryozoa zooecia with phosphate inftil ings in continuity with the truncation and bounded by sparry calcite support the hypothesis that the phosphate was present before the grain was abraded and was transport ed along with the allochem. Cressman (1973) reports that calcarenites from the Lexington Limestone of central Ken tucky contain 0.8 percent to 2.4 percent phosphate. Wil son (19^9) similarly reports the presence of phosphate in the lithologic equivalent Bigby-Cannon Limestone Formation in the Nashville Group of Tennessee. Chert is commonly observed replacing allochems in some of the thin sections. This silicification is second ary in origin and can be seen transection grain boundaries. Opaque minerals, hematite and limonite are observed in trace amounts. They usually are associated with sty— lolites, veinlets or in fillings of fractures. Applicable names. Microscopically limestone names vary from biopseudosparrudites, biosparrudites, bio- micrudites, biomicrosparrudites, biomicrosparites to bio- sparites (Folk, 1939)* In the terminology of Dunham (1962) rocks would range from wackestones, packestones to grainstones with the most common name being grainstones. 33 Subclass 1-2 Megascopic description. Megascopically rocks in tills category are light—gray (N7)9 medium—light—gray (N6), light—olive-gray (5Y6/l) to olive—gray (5Y4/l) medium- grained, moderately—well—sorted calcarenites (Fig, 8), The most abundant allochemical constituents are fossil fragments and to lesser amounts intraclasts (Table 2), Allochem size is usually less than 1 mm. Cross lamina tions, cross bedding, and horizontal laminations are com mon within this lithology (Fig. 8). Stylolites are very common. Large stromatoporoids which appeared whole were observed. Common to this subclass is a yellow to yellow brown stain which may be either limonite infiltrating be tween laminae and bedding surfaces and coating grains or phosphatic material infilling between and among grains. Microscopic description. Petrographic examina tion of this subclass revealed that it is almost identical to the previous lithology (subclass l-l). Fossil and intraclastic allochems are similar in name, abundance, distribution and condition of preservation (Fig. 8). How ever, allochem size is generally smaller, averaging less than 1 mm, with sorting among allochems generally better, ranging from fair to well sorted (Fig. 8). Orthochemical constituents, replacement and second ary minerals are similar in abundance and in relationships 5k Figure 8. Subclass 1-2 limestones. A. Polished core slabs oriented so the top is stratigraphically up. Notice horizontal and cross lamination. Lower left hand specimen shows con tact between subclass 1-2 and class h limestone. B. Example of* crossbedding in subclass 1-2 limestones. Bigby Formation, Tennessee. C. Upper unit in photograph is cross bedded Tanglewood Limestone Member of Lexington Limestone. Gently dipping crossbeds can be observed just above contact between Tangle- wood Member and tongue of Clays Ferry Formation (middle unit). Chuck Quappe pointing to contact of Sulfur Well Member of Lexington Limestone and a tongue of Clays Ferry Formation. D. Typical subclass 1-2 grainstone. Notice abundance of fossils. a. Allochemical ghost. b. Syntaxial overgrowth on pelma tozoan grain. c. Phosphatized pelmatozoan. d. Overly close packing between two micritized allochems. e. Neomorphic calcite transecting rounded phosphatized pelmatozoan grain to left of the letter. 55 to each other* and allochemical grains. The petrographic discussion of subclass 1-1 also pertains to subclass 1-2, Applicable names, Biosparites, biopseudo— sparites, and an occasional sparry biomicrite (Folk, 1959)> waclcestones to grainstones categorize this subclass of limestones• Environment of deposition of subclass 1-1 and subclass 1-2 limestones, A relatively shallow water, high mechanical energy environment is postulated at the deposi tion site at which subclass 1-1 and subclass 1—2 sediments accumulated. Henceforth these two subclasses will be call ed the grainstone facies. Fossil fragments which are ex tremely abundant and intraclasts show signs of transporta tion, abrasion and rounding, Phosphatic grains and rounded fossil fragments concentrated in laminae and bedding sur faces are a good indication that currents were actively distributing, rearranging and shaping allochemical frag ments, A majority of the limestones are classified as grainstones, Grainstones generally indicate sediment deposition and accumulation in agitated waters (Dunham, 1962), Grain—supported textures, especially embayed grain contacts and overly close packing are common. Floored interstices and sheltered areas are very rare because severe neomorphism has altered the original fabric of the matrix, 57 Megascopically, cross—bedding and cross—laminations along with, parallel laminations and bedding are observed within this facies, Ilrabar, Cressman and Potter (l97l) report low-angle, small— to medium-scale cross—bedding within the Tanglewood member of the Lexington Limestone Formation (Fig. 8C). The cross-beds are generally planar ranging from 3 to 5 inches to several feet thick. Low angle cross-beds have also been reported in parts of the Devils Hollow Member of the Lexington Limestone Formation (Cressman, 19735 Etter, 1973)* The Bigby Limestone (Fig. 8D) within the Nashville Group near Tennessee is in the words of Wilson (1948, p. 2l), "so extensively cross bedded that horizontal bedding planes are usually difficult to distinguish." Stratigraphic correlation between this study and the work of Cressman (1973) and Wilson (1948) revealed that many of the grainstone facies rocks were taken from these above members and formations. Subclass 1-3 Megascopic description. Limestones in hand specimen range from light—gray (N7) to medium-dark-gray (3YR4/l) to olive-gray (5Y4/l), fine-grained calcalarenites to calcisiltites (Fig, 9)* Fossil fragments and intra- clasts, mostly calcareous mud chips, are common. Moderate ly well to well sorting among allochemical grains is pre sent. Rocks are usually finely laminated. Horizontal or 58 Figure 9* Subclass 1—3 limestones. A. Polished hand specimens of subclass 1—3 calcarenites and calcisiltites. Top of photomicrograph is strati— graphically up. Specimen on left shows interlamination with class 2 calcilutites• B. Fine-grained calcarenite (grain- stone). Notice abundance of fossil fragments. a. Badly comminuted pelmatozoan. b. Aliochemical ghost. c. Micritized trilobite fragment. Black materials are opaque minerals. Notice the patchy distribution of micrite in sparry calcite cement which is sugges tive that much of this sparite is neomorphic in origin. C. a. Large micritized trilobite frag ment surrounded by fine-grained matrix composed of micrite and sparry calcite. D. Secondary dolomite in micrite matrix. Notice intergrown boundaries among some of the dolomite rhombohedra. 59 0 .5 m m 60 parallel laminations are most abundant followed by cross laminations (Table 3)• Mottling; effects which disrupt laminae are more abundant in this lithology than in the previous two subclasses (Table 3)# Diagenetic stylolites were observed to a lesser extent than in the previous class 1 lithologies. Stromatoporoids were noticed in similar abundance and appearance as in subclass 1-2 limestones* Microscopic description. Fossil grains are highly abraded, fragmented and comminuted (Fig, 9)* Their size range is generally small, averaging much less than 1 mm. The abundance of fossil allochems is much less than in the previous class 1 lithologies, ranging from less than 10 percent to 50 percent with the average being approxi mately 20 percent. Fossil recognition is more difficult but the same general fauna are present. Pelmatozoans, brachiopods, bryozoans and trilobite fragments are the major constituents followed by mollusk and ostracod frag ments. Sorting within the allochems is fair to good. Coated grains taken to be signs of micritization are pre sent in quantities abundant enough to suggest the work of boring organisms. Among the matrix materials neomorphic sparry calcite is the dominant sparite species. Size range is from micro- spar to pseudospar. Pore filling calcite cement is present only in minor quantities. Micrite is abundant and in many 6l thin sections is interbedded with calcisiltites and in soluble clay layers# Dolomite is common to abundant, ranging from less than 5 percent to greater than 60 percent of the thin section (Fig# 9D)• The dolomite is secondary in origin as was previously discussed. Detrital clay and silt content in some thin sections ranges from 10 percent to 30 percent and usually occurs in laminae of beds# Minor currents may have been operative at this depositional site which alternately delivered carbonate and non-carbonate sediments• Phosphate appears in lesser amounts than in the previous class 1 lithologies# Wien observed it is as a replacement in crinoid fragments, filling in stylolites or as infillings in bryozoan and gastropod fragments# Applicable names# Microscopically, fine-grained laminated biosparites, biomicrosparites, dolomitized sparry micrites and dolomitized clayey micrites (Folk, 1959)9 wackestones to grainstones (Dunham, 1962) encompass the names given to these rocks. Fine-grained biosparites (grainstones) are the most common lithology# Environment of deposition. The mechanical energy which existed at the depositional site where sub class 1—3 sediments (fine grainstone facies) accumulated was one of slightly lower energy than in the grainstone facies# Currents and agitated conditions existed but were 62 of lesser magnitude than the other class 1 grainstones. Currents were incapable of delivering larger fossil frag ments as evidenced by the overall smaller grain size which is present within this facies. It is possible that larger fossil grains were not available for transportation but this is unlikely since the fossil allochems within this subclass are the same as the allochems in the coarser grainstones of class 1, packestones of class 3 and wacke- stones of class 4. In addition to being finer grained., allochems within this facies are better sorted, abraded and show signs of transportation. It seems reasonable to assume that the stronger currents associated with grain- stone facies winnowed the finer sized fragments to an area of lesser mechanical energy and deeper water where they were deposited. The abundance of micrite and detrital clays which are commonly interbedded and interlaminated with the fine grainstone facies suggest (Fig. 9) that cur rents may have fluctuated or may have been periodic. Megascopically, both cross—bedding, cross lamina tions and parallel laminations are present. Mottling ef fects were also more noticeable in hand specimen than in the other class 1 lithologies. If this effect is biologic in origin, it may indicate quieter deeper water which would be more desirable for burrowers and for the preserva tion of such biogenic features. 6 3 Class 2 Megascopic description Irregularly bedded, medium-light-gray (n6), medium- dark-gray (N^) to olive-gray (5Y4/l), argillaceous cal- cilutites to calcareous shales characterize class 2 lith ologies (Fig. 10). Fine laminations and small intra clasts are common but are not ubiquitous. Xn hand specimen the most noticeable characteristic of* the rocks is that they are very Friable and crumbly. This is most likely due to poor cementation. Xnterbedding of calcilitutes and shales is common. Silty laminae are also noticed and ap pear to be dolomitic in nature. Bioclastic Fragments are observed but are a minor megascopic characteristic oF the rock. Mottling or disruption oF bedding appeared in a Few polished slabs. Cross laminations were observed along with parallel laminations (Table 3)* This may be indica tive oF minor currents acting in the area oF deposition. Microscopic description Fossil allochems are sparse (less than 10 percent) and show no preFerred orientation (Fig, 10). In one thin section they comprise approximately 30 percent oF the rock. IdentiFiable Fragments are brachiopods, pelmato— zoans, and trilobites with lesser amounts oF mollusk and ostracod debris. They are severely abraded and Fragmented with sizes averaging less than 1 mm. Intraclasts, when 6k Figure 10* Class 2 limestones* A* Polished hand specimens of argil— luceous calcilutites• Notice Pine laminations at bottom of the core specimen on the right* Upward is toward the top of the photograph* B. Calcilutite with fine-grained fossil hash* a* Fossil fragments, most likely mollusks * b. Micrite and insoluble clays* c. Dolomite rhombohedra* C. Dolomitized micrite. a. Large dolomite rhombohedra to the left of the letter a, ap parently has grown at the ex pense of the micrite. Close examination of other edges of grain shows that it is zoned, suggesting secondary origin* b. Micrite* D* Class 2 calcilutites and calcareous shales interbedded with class 1 limestones, Clays Ferry Formation, Kentucky. 65 66 observed, appear as mud blebs or chips of calcareous and non-calcareous composition. Irregular and angular boundaries suggest that they are fragmental and have not been transported a great distance to the depositional site . Micrite is the most abundant carbonate matrix material varying in abundance from 10 percent to 70 per cent, averaging about h0 percent of the rock. Dolomite comprises 30 percent of the thin sections but may vary from less than 10 percent to greater than 50 percent (Fig. IOC). It is h fa to h0 fa in size and is rhombohedral in geometric outline. It zoned when viewed under the lumino- scope and is observed transecting grain boundaries. The nuclei of the zoned dolomite does not appear abraded or worn. Although dolomite sometimes appears with detrital grains of similar size, there is no conclusive evidence that the dolomite is allogenic in origin. A secondary origin for the dolomite is suggested. Insoluble clay and silt size materials are a major constituent within this lithology. Their abundance varies from 20 percent to 70 percent in thin sections with the average approximately 30 percent. Silt size quartz grains are the most easily recognized detrital grains and along with the other insoluble materials suggest a terri genous source for some of the sediments contained in this rock class. 67 Thin sections commonly show horizontal laminations and to a lesser amount bedding' usually alternating in lithologies. Dolomite is usually associated with the micrite laminae which is commonly interlaminated with detrital silts and clays. Xn the more calcareous thin sections, dolomite may be interlaminated with micrite or the micrite itself* may be laminated with patchy zones of dolomite. The shaley rocks also show interlaminations whether calcareous units are present or not. Mottling effects of disruptive bedding is commonly observed within some samples. This may be due to either burrowing organisms which might also explain the patchy distribution of dolomite, or to pressure exerted by over- lying layers, the result being soft sediment deformation. Applicable names Class 2 rocks range in petrographic names from micrites, clayey micrites, dolomitized micrites, sparse biomicrites (Folk, 1959)* mudstones and wackestones (Dun ham, 1962) to calcareous shales. Environment of deposition Class 2 (the shaley carbonate mudstone facies) sedi ments were deposited in quiet deeper waters where current action and agitation were at a minimum. Horizontal lamina tions of alternating lithologies (micrites, detrital clays, and dolomitic layers) were commonly observed both in hand 68 specimen and in thin sections* This may indicate that minor currents were operative in the area* However, the small grain size and the lack of fossil fragments along with the abundant silt and clay materials suggest a low energy, relatively deep water environment. The mixture of calcareous and non—calcareous sediments suggest more than one source area. Examination in the field (Fig. 10D) and in the logged cores revealed that class 2 rocks are usually inter- bedded with the fine grainstone facies (subclass 1—3)* This alternation of lithologies most likely represents episodic introduction of coarser grained material into an area of quiet, deeper waters where fine-grained carbonates and terrigenous clays were accumulating. Class 3 Megascopic description Irregular to nodular bedded, light-gray (n6), medium-gray (N3), to olive-gray (5Y5/1) colored, fine- to coarse-grained calcarenites with shale partings mega- scopically identify class 3 limestones (Fig. ll). Fossils are abundant, the most conspicuous being brachiopods, bryozoans and gastropods. Intraclasts are a common feature in rock slabs (Table 2). Clay content ranges from 10 per cent to 20 percent of the total rock. Sorting appears poor due to a wide range in aliochemical sizes. No sedimentary 69 Figure 11* Class 3 limestones. A* Polish, core slabs. B. Microphotograph of class 3 packe— stone• a. Rounded intraclast with included dolomite rhombohedra. b. Micritized fossil fragment (mollusk) barely recognizable. c. Distinct contact between intra- clast and sparry calcite cements suggesting transportation to deposition site. d« Micrite patches in sparry cal cite suggestive that neo morphism has produced much of the sparite. C. a. Rudite size bryozoan grain. b. Recrystallized fossil fragment, possibly a pelmatozoan. c. Micrite. d. Recrystallized zone of sparite enclosing previously existing micrite• D. Wackestone fabric, dominately micrite. Dark black patches are opaque materials possibly phosphate. a. Large brachiopod fragment. b. Mollusk, comminuted and re- crystallized. 70 uiuiS'O structures, i.e., cross-beds, cross-laminations, horizontal laminations or layers were observed while examining core samples• Microscopic description Fossil allochem abundance varies From 15 percent to 30 percent within the thin sections. Pelmatozoan, brachio- pod, bryozoan and trilobite Fragments are common (Fig. ll). Mollusks appear in lesser amounts. Fossil sizes range From a Fine hash (less than 30 f*) to coarse-grained (great er than 3 mm)• Sorting among allochemical grains is poor. Fossils are Fragmented, abraded and some intraclasts show signs oF transportation (Fig. 11B). Some large, whole Fossil Fragments were also observed. Fossil grains show no preFerred orientation. Recrystallization was noticed in some Fossil grains especially within the mollusk Fraction. Coated grains were also observed but not to the extent as in class 1 limestones. Among the calcareous orthochemical constituents both micrite and sparry calcite are common. The dusty appearance oF the sparry calcite, patches oF micrite in sparite zones, abundant allochemical ghosts, and Few enFacial angles (Bathurst, 1966) suggest that a majority oF the sparry calcite is neomorphic in origin. This neo- morphic sparite is microspar to pseudospar in size. Clear sparry calcite was noted in a Few zones surrounded by 72 micrite. This may be pore filling calcite which has filled in a void or a possible burrow. This is highly speculative because no clear-cut boundaries or truncated grains which one might expect at the boundaries of a bur row were observed. Dolomite appears in excess of 10 percent (Fig. ll)* It usually occurs as rhombohedra ranging in size from 20^u to 50 yu and is found mostly associated with the finer grained micrite and detrital clays. Xt is secondary in origin as evidenced by dolomite crystals transecting allo chemical grain boundaries, and excellent zoning among crystals when viewed with the luminoscope. Phosphate is present as infillings in some allo chems and as a partial replacement in some crinoid frag ments, trilobites and brachiopods. Insoluble clay and silt minerals appear as partings or layers between calcareous units. They comprise approxi mately 10 percent to 20 percent of the thin section by volume• Embayed grain contacts and overly close packing, indication of a grain support fabric, were observed in only a few of the thin sections. Floored interstices and sheltered areas were not noticed. The majority of the thin sections showed no evidence of grain support and ap pear to be matrix supported. The resulting packestone fabric is most likely the result of compaction. 73 Applicable names Biomicrosparrudites, biomicrosparites, sparry bio- raicrites (Folk, 1959)* and packestones (Dunham, 1962) identify this class of limestones microscopically. Environment of deposition A moderately agitated mechanical energy, intermediate but fairly shallow depth condition, is postulated for the environment of deposition for class 3 sediments (packe- stone facies), Allochemical grains show signs of abrasion, transportation and comminution. Fine-grained carbonates and insoluble clay and silt appear to have been the majority of the original matrix. Currents were most likely present in sufficient magnitude to deliver some fossil grains to the depositional site but were not capable of winnowing out much of the fine-grained materials and those fossil grains which may have actually lived in situ. Micritic coatings on grains were observed in thin sections which suggests much of the fine—grained carbonate may have originated from the work of boring and burrowing organisms. Megascopically the packestone facies is commonly separated by fine—grained carbonate and shale partings. This possibly represents periods of quiescence, lack of fossil production or introduction of materials from another source. These fine-grained partings may also possibly represent erosional surfaces, but no direct evidence of 7k this was observed in the cores or hand specimens. Cressman (1973) reports faint cross-bedding in some exposures within the Grier Limestone Member of the Lexing ton Limestone Formation. Many of the thin sections and hand specimens studied were taken from this member. Class 4 Megascopic description Rocks of this lithology are typically medium-gray (N5) to olive-gray (5Y^/l) in color, very fine- to coarse grained, irregular to rubbly-bedded, clayey calcirudites to rudaceous calcilutites (Fig. 12). Large intraclasts and large fossil fragments are abundant megascopically (Table 2). Fine-grained material which includes both micrite and detrital silts and clays varies in abundance from 30 percent to 80 percent by volume. Sedimentary structures are generally absent although a mottled appear ance was present in several instances. Microscopic description Biogenic fragments in abundance are brachiopods, bryozoans, pelmatozoans and trilobites (Fig. 12). Ostra— cods and mollusks are common. Fossil grains comprise 30 percent to 50 percent of the rock thin sections. Their grain size ranges from fine hash, less than 30 /u, to rudite in size. Brachiopods and bryozoan fragments are commonly 75 Figure 12. Class 4 limestones. A. Polished hand specimens. Notice large whole fossil grains along with large intraclasts (upper left specimen). Top of photograph is stratigraphically up. Darker area contains high amounts of litho— genous sediment. B. Rubbly bedding characteristic of Class 4 limestones. Scale is 14 cm long. Millersburg Member of the Lexington Limestone Formation. C. Wackestone fabric characteristic of Class 4. a. Recrystallized badly comminuted fossil grains in micrite matrix. b. Mollusk fragment. c. Micrite with a recrystallized pelmatozoan below. D. Class 4 wackestone. a. Phosphatized pelmatozoan. b. Opaque infilling. c. Micrite patches in sparite with ghost structure below, possible brachiopod fragment above. d. Fossil fragment probably a trilobite floating micrite. 7 6 0 .5 m m 77 greater tlian 10 mm with some bryozoan exceeding 20 mm (Fig. 13). Sorting among allochemical elements is poor. The fossils are mostly abraded and show some signs of* rounding, especially among the larger bryozoan fragments. However, large whole continuous brachiopod shells are commonly observed with their orientation parallel to bedding. Micritic coatings are commonly observed outlin ing allochems and are most noticeable around trilobite and ostracod fragments. Xntraclasts occur within the thin sections but not to the extent that they are observed in hand specimen. Some excellent intraclasts are observed (Fig. 13) with clear boundaries and textures distinct from the surround ing matrix. Some are rounded and show signs of abrasion (Fig. 13B). Allochemical distribution within the thin sections is in many instances very irregular and patchy. Bio- clastic zones appear commonly as calcarenite and grain- stone patches surrounded by a finer matrix. Their bound aries are indistinct and gradational. The general overall appearance of these patches is very similar to class 1 or class 3 limestones. These zones may have been intra clasts which were removed in a semi—plastic state from their original environment of deposition and redeposited. Subsequent bioturbation, diagenesis, currents, or disrup tion and deformation due to overburden may have made the 78 Figure 13* Class h limestones. A. Wackestone fabric. a. Rudite size bryozoan, opaques infilling zooecia. b. Micrite and dolomitic matrix mixed with lithogenous sedi ments. Notice comminuted fossil fragments in upper right from letter b. B. Calcirudite. a. Large transported intraclast with included fossil fragments. b. Matrix of dolomite mixed with lithogenous sediments and micrite• c. Dolomite with intergrown boundaries. C. a. Abraded allochem grains, possibly brachiopods. b. Matrix which contains insoluble clays, silts and lime muds. D. a. Large bryozoan infilled with phosphatic materials, b. Dolomitized matrix with rhom bohedra boundary commonly inter- grown. Dusty appearance of dolomite suggests that it ap pears to be growing at the ex pense of the fine—grain matrix. 79 0 .5 m m 80 boundaries indistinct. Another alternative is that the patchy grainstone zones represent remnant bedding and any or all of* the above are responsible for destroying the original fabric of the rock. Within the matrix calcareous constituents comprise 30 percent to 80 percent, averaging 40 percent by volume. Of these micrite is the most abundant followed by sparry calcite. Comminution of fossil grains by boring organisms and burrowers is a likely source for some of the micrite as evidenced by the micritic coatings around allochems which are commonly observed. Mechanical abrasion of allo chems and transportation of micrite to the depositional site by currents must also be considered. High insoluble clay and silt content (lO percent to 50 percent) within the fine-grained matrix, and fragmented and rounded allo chems support the premise that currents were present and introducing material from another source. The sparry calcite is mostly neomorphic in origin. Good ghost structures, sparite transecting grain bound aries, patchy zones of micrite in sparite areas, sparite patches in micritic areas and dusty appearance of the sparry calcite suggest this. The neomorphic calcite ap pears as anhedra ranging from microspar to pseudospar in size. Pore filling calcite cement is present in minor quantities. Several good umbrella structures of pore fill ing cement with optic axis oriented perpendicular to grain 81 boundaries were observed on the underside of large allo chems • Some pore filling calcite cement was also observed within intraclasts and disruptive grainstone areas. Dolomite is a common orthochemical constituent which may vary from less than 10 percent to 40 percent within the carbonate fraction (Fig, 13b). It is commonly found associated with the fine—grained materials. It is also observed in patches and around fossil allochems. Good zoning of crystals under the luminoscope and dolo mite rhombohedra transecting grain boundaries support the hypothesis that the dolomite is secondary in origin. Insoluble clays and silts are present within the rock matrix. They are also concentrated in stylolites and veinlets. Quartz, feldspar, phosphate and pyrite along with other opaque minerals were identified, Pyrite was observed as a replacement mineral in a few trilobites. Phosphate commonly occurs in some bryozoa zooecia and pelmatozoan fragments (Fig. 13A). Some trilobites and conodont elements also have a phosphatic nature. Silici- fication of some brachiopods was present. The general texture of the examined rock thin sections is one of mud support. A few grain—supported structures were noticed within intraclasts and biosparite zones but these were minor on occurrence. No positive evidence exists within this class of rocks to suggest they were originally grain-supported. 82 Applie ab1e name s Clayey biomicrudites, biomicrosparrudites, bio- intramicrites, biointramicrudites and dolomitized bio — micrites (Folk, 1959) or wackestones and packestones (Dun ham , 1962) microscopically categorize this class of lime stones* Environment of deposition A moderately agitated to sligbtly agitated mechani cal energy condition with water depths greater than class 3 packestones is suggested for the depositional environ ment for the sediments which comprise this wackestone facies* Matrix supported wackestones and to lesser ex tent packstones containing abundant fine-grained carbonate and noncarbonate materials suggest a moderately quiet water environment of deposition. Large, diversified fos sil grains and intraclasts often show signs of mechanical abrasion and transportation which suggests that some cur rents were active at the deposition site. However, cur rents were insufficient in magnitude to remove the micrite, detrital clays and silts and the smaller fossil fragments. The large whole allochems which commonly ap pear also suggest current activity was minor and that these organisms were productive in the area. Micritic coatings on many fossil grains suggest that much of the micrite and smaller fossil fragments may have been produced 83 by tbe boring algae, fungi, bacteria and burrovers, The nodular and rubbly bedding in field units and in the cores logged also suggest burrowing organisms were pre sent and active. Fine-grained carbonate is also as sociated with detrital silts and clays. It is possible that some of the micrite may have been mechanically trans ported to the depositional site along with the non carbonate fraction. Class 5 ■ ' I Megascopic description Rocks in this class are pinkish-gray (5YR7/1), greenish-gray (5GY6/l) to light-olive-gray (5Y6/1) colored, fine-grained calcilutites. In hand specimen the rocks ap pear cryptocrystalline in grain size (Fig. 14a) . Horizon tal and vertical burrows are abundant (Table 2). This pro duces a mottled appearance which is characteristic to this class of limestones (Fig. 14b). A birdseye texture is also common which may either be due to biogenic activity or to gas trapped within algal structures which was pro duced from decaying organic material. This gas produced voids which were later infilled with crystalline calcite. Laminations which appear to be algal in character are com mon. Bioclastic debris is also common. The most notice able fossil grains are recrystallized gastropod and pele- cypod shells. Intraclasts are minor in abundance. 84 Figure 14. Class 5 limestones. A. Polished, hand specimens. a. Birdseye texture. Lower right hand specimen shows possible algal laminations. Upper left hand specimen suggestive of bioturbution. B. Class 5 limestones in field. Notice vertical burrowing which ap parently produced birdseye texture. Horizontal bedding and lamination are suggestive of algal structures. Scale 15 cm. Dove limestone, Tennessee. C. Biomicrite. a. Large whole recrystallized fossil (mollusk) floating in a micrite matrix with other com minuted fossil debris. D. a. Ostracod fragments floating micrita matrix. b. Recrystallized mollusk (gas tropod) . 85 86 Microscopic description Fossil allochems which comprise 0 percent to 30 percent of the thin sections by volume are ostracods, trilobites and mollusks (Fig. l4). Gastropods are the most conspicuous mollusk followed by pelecypods. Minor amounts of brachiopods and bryozoan fragments were ob served. Fossil size and condition of preservation is ex treme. In some thin sections fossil identification was very difficult. Fauna was abraded, comminuted and ap peared as nothing more than a fine hash. In other thin sections fossils were greater than 1 mm continuous and whole (Fig. 15)# Duplicature of ostracod tests was ob served. Large whole gastropods were also present. Com monly observed was a combination of both textures; a fine grained fossil hash matrix and large whole mollusks and trilobites. Located within many whole gastropod shells were concentrated amounts of fine ostracod hash. Whether the ostracods were ingested by gastropods or transported into the shells is an interesting question. Surrounding some of the gastropods is fossilferous debris of similar composition and abundance as the material inside the gastropod. This would support the hypothesis that the material inside the gastropod was transported into the shell or filled in after the death of the gastropod. In other instances the surrounding matrix contains signifi cantly less fossil fragments than within the gastropods. 87 Figure 15- Class 5 limestones. A. a. Recrystallized rudite size mollusk (gastropod). b. Crypotocrystalline matrix of lime muds. c. Patchy sparite zone in micrite suggestive of borrowing. B. a. Glauconitic intraclast surrounded by dolomitized micrite. C. a. Mollusk fragments and other fossil hash in fine—grained lime muds . b. Dolomitized zone. D. a. Micrite area with fibrous appearance which may be pre served algal filaments, b. Recrystallized fossil debris. Notice that filaments ( ?) con tinue into recrystallized zone. 88 68 luuigo This suggests that possibly the gastropods were active and grazing in the area of deposition. Recrystallization of fossil grains is very common especially within the mollusk fragments (Fig. 15)• Micritic coatings on allochemical grains are also common which s\iggest the work of boring organisms• Xntraclasts occur in minor abundance within the examined thin sections. Some of the intraclasts appear as small micritic blebs or chips and are commonly angular in outline. Larger intraclasts were observed and appear to be glauconitic in composition. They are green to dark green in color and have included pyrite and dolomite rhombohedra (Fig. 15b). They are distinct from the sur rounding matrix and are angular in shape which would sug gest they have not been transported a great distance. Micrite is the most abundant matrix material vary ing from 50 percent to 90 percent by volume. It appears both in laminations of probable algal origin (Fig. 15D) and in the nonlaminated state. It is present as inftil ings in fossil gastropods and bryozoa and also as floating relicts in sparite zones. The micrite was probably pro duced by normal disintegration of fossils and by the breakdown of grains by boring organisms. It was then trapped and binded by algae which produced the laminated form. Disruption of laminae by burrowers of pressure due to overburden may have produced the nonlaminated variety. 90 Other micritic laminations not of algal origin may have been produced by minor currents which were active in the depositional area. Sparry calcite occurs in recrystallized allocheras (Fig. 15), in void filled areas and patches surrounded by micrite, in veins and burrowed areas. The sparry calcite is microspar to pseudospar in size. Pore filling cement is present in some void areas, but the majority of the sparite is neomorphic in origin. Good transection of sparite grains across allochem boundaries, recrystalliza tion of allochems, micritic patches in sparite zones and the general mud support character of the rocks support this statement• Dolomite is an abundant constituent within the examined thin sections. Its variability in abundance ranges from 15 percent to 50 percent. The dolomite is rhombohedral in outline, 30 ya to 60yu in size and commonly occurs as laminae interbedded with micrite. It is dia- genetic in origin as evidenced by dolomite crystals transecting grain boundaries (Fig. 15C)• When viewed under the luminoscope the dolomite is zoned with inter grown boundaries commonly observed. Insoluble clays and silts comprise less than 10 percent of the rock in thin section. Some silt size quartz and feldspar was identified. Minor amounts of phosphate and chert were observed in infillings and re- 91 placements in some fossil allochems. Pyrite in rhombic form possibly replacing dolomite and other opaque minerals were observed in trace amounts. Many of the tbin sections have a mottled character. Associated with this disruptive texture are severely abraded and comminuted fossil fragments and sparite patches dispersed through the rock sections. This suggests that burrowers were active at the depositional site and the resultant mottled birdseye texture is the result of such activity. In other thin sections fine undisturbed lamina tions occur in conjunction with birdseye structures. Xt is postulated that the laminations are algal in nature and the birdseye texture is a result of calcite filling in voids which were originally gas pockets produced by de— c aying algae. The general overall appearance of the thin sections is one of mud support. No grain—supported structures were observed which would suggest otherwise. Applicable names Laminated micrites, biomicrites, dolomitized micrites and dismicrites (Folk, 1959)> carbonate mudstones and wackestones (Dunham, 1962) identify class 5 limestones microscopically. 92 Environment of deposition Tlie area of accumulation of class 5 sediments (re stricted carbonate mudstone facies) was one of relatively low mechanical energy and relatively shallow water. Abundant micrite, many whole fossil mollusks and ostracods suggest an area of very little mechanical agitation and current activity. The abundance of gastropods, ostracods and less commonly trilobite fossil fragments along with the absence of the more open water faunas (brachiopods, bryozoans and pelmatiozoans) suggest that these waters were somewhat restricted in comparison to the other class 1 through class b limestone facies. Comminution of fossil allochems is probably the result of boring and burrowing infauna, which is also a likely source for the abundant micrite. The micritic coatings commonly found on allo chems and the mottling and birdseye textures found within these mudstones are a good indication of biologic activity. Slight agitation by waves and minor currents may have been operative in this environment as suggested by some rounded intraclasts and abraded fossil fragments which are found within these mud-supported limestones. Algal laminations are present within some examined hand specimens and thin sections. The binding and holding ability of algal mats and films is capable of masking any energy conditions which may exist in an area. In addition, subsequent burial of these films results in their complete disintegra 93 tion from which no fossil evidence exists of tliem ever be ing present (Bathurst, 197l)* At the depositional area of this restricted carbonate mudstone facies energy conditions can only then be speculated. Class 6 Megascopic description This lithology consisted of a light-olive—gray (5Y7/l), pinkish-gray (5YR7/1) to light-olive-gray (5Y6/1) colored, fine— to coarse-grained rudaceous calcilutite to clayey calcirudite (Fig. 16). Megascopically intraclasts are the most common allochemical constituent (Tables 2 and 3). Fo ssil fragments are next in abundance. Fine grained material ranges from approximately 20 percent to 60 percent. Either currents, overburden or bioturbation produced a mottled character which is common in many of the hand samples. Bedding is characteristically irregular to rubbly (Fig. l6B). Class 6 limestones closely resemble class h limestones with one exception. The intraclasts in class 6 rocks are identical to class 5 lithologies, i.e., they are mottled, contain birdseye structures, are some times laminated (suggestive of algae) and have the very fine grain texture and color characteristic of class 5 ro cks. 94 Figure 16. Class 6 limestones, A, Polished hand specimens. a. Vertical burrow to the right transecting fossil grains. Notice rounded geopetal structure in same area with central area recrystallized and lighter lime muds at the top. B. Leonard Alberstadt pointing to contact of Cannon Limestone (class 6 equivalent) below and Catheys Formation above. C. Photomicrograph with a. Recrystallized allochems (mollusk and ostracods)• b. Micrite with badly comminuted brachiopods and fossil hash. D. a. Recrystallized and micritized whole mollusk grain. Notice micrite appear to obliterate continuous shell structure. b. Sparite patches in predominately a micrite matrix. c. Micrite zone floating in sparry calcite area. 95 0 I 2 £ t > oiD g 9 I 8 6 0 1 Microscopic description Fossil grains constitute approximately 30 percent to 40 percent of the thin sections* Mollusk, trilobite and ostracod grains are most abundant. However, unlike class 5 limestones a greater representation of* brachiopods, bryozoans and pelmatozoans are present (Fig. 17)* The majority of the fossils are comminuted and fragmented with many showing signs of rounding and transportation. Many fossils are whole and rudite in size, a few brachiopods exceeding 3 mm. Duplicature of some ostracod shells is observed. Micritic coatings on fossil fragments are very common (Fig. 17B). Recrystallization is very common, es pecially within the mollusk shells (Fig. 17C). Sorting among allochems is poor. Allochems show no preferred orientation. Xntraclasts which megascopically are abundant ap pear in lesser amounts in thin section. This is a function of size. In hand specimen they are most noticeable and large. Microscopically one large intraclast may comprise the entire thin section. ¥hen observed in thin section the intraclasts appear to be identical with class 3 litholog— ies. Intraclast boundaries are sometimes vague, unclear and gradational which may be the result of either bio— turbation, which is supported by the mottled fabric of this rock, or by the transportation of intraclasts in a semi—plastic state to the deposition site. 97 Figure 17# Class 6 limestones A. a, Rudite size brachiopod. b. Micritic matrix witb ostracod hash.* B. a* Large rudite size bryozoan* b. Micritic matrix containing ostracod hash. C. a. Large fossil ghost (gastropod). b. Neomorphic sparry calcite. c. Sparite patch located in matrix of micrite and opaque materials. D. a. Zoned dolomite rhombohedra ap parently being dedolomitized in a matrix of micrite and small fossil grains, b. Large abraded fossil pelmatozoan fragment. 98 66 uiuig'O Within the matrix materials, micrite is most abundant, averaging approximately 50 percent. Sparry calcite is present in patches and in recrystallized allo chems and appears to have been the result of neomorphic processes (Fig. 17C). Dolomite is present (lO percent to 30 percent) and shows evidence of being secondary in origin (Fig. 17D)• Insoluble clays and silts constitute from 10 percent to 20 percent of the matrix. Phosphate and silica were observed as infillings and replacements some fossil crinoids and brachiopods. Opaque minerals which included pyrite were also observed. Insoluble and terrigenous clay and silt content is also increased. The terrigenous clays and silts mixed with fine-grained carbonate material appear as partings between areas that are identical to class 5 carbonates. This produces an irregular to rubbly bedded fabric characteristic of class 6. In all other aspects class 5 and class 6 rocks are similar. This includes condition and preservation of fossils, rock textures, relationships between matrix and grains (mud supported), and secondary and replacement minerals. Applicable names Microscopically class 6 rocks are very similar to class 5* Class 6 limestone names range from laminated bio — IOO micrites, micrites, sparry biomicrudites and dismicrites (Folk, 1959) or wackestones to packestones (Dunham, 1962). Environment of deposition Mechanical energy conditions at the deposition site of sediments which comprise class 6 wackestones and pack— stones (restricted wackestone facies) are postulated as slightly agitated and shallow, but slightly deeper waters than those rocks which comprise the restricted carbonate mudstone facies. Within this facies transported and abraded fossil allochems are observed. Some intraclasts also show signs of rounding and transportation. Megascopically the intra- clasts are more apparent and along with the fine-grained matrix materials produce the irregularly bedded to rubbly fabric characteristic of the facies. These intraclasts, identical to class 5 lithologies, may have been transported and re-deposited in this slightly deeper water area. Abundant ostracods, gastropods and trilobites suggest that these waters were also somewhat restricted as compared to class 1 through class *+ lithologies. Additional bio clasts which appear commonly in class 6 rocks (brachiopods, bryozoans and pelmatozoans) were possibly derived from another source or an in situ in origin. Whole fossil grains are common and also suggest production in situ. Micrite is abundant throughout the rocks and sug— 101 gests tliat currents were insufficient to remove much of the fine-grained materials. Micritic coatings on fossil grains are common and suggest much of the micrite was derived in place and can be attributed to boring and burrowing organisms which may also explain the character istic texture within these rocks. The insoluble clays and silts associated with the micrite may possibly have been derived from another source area and may indicate that some of the micrite was transported to the deposition— al site. Conodont Analysis The entire length of core number Ca-179 was analyzed for conodonts* The procedures involved in separating and preparing the samples for identification were (l) weighing of the rock samples, (2) dissolving the limestones in 10 percent acetic acid, (3) weighing the insoluble residue, (4) bagging and labeling the samples, and (5) shipping the samples to Dr. Richard Miller, Cali fornia State University at Northridge, for identification. A summary of the conodont identification is given in Table B of the Appendix along with the insoluble residue data, depth of the sample, and the rock type that was dissolved. The relative conodont abundances and ranges were also graphed and are presented and discussed in the results section. 102 Definition of the Time-Stratigraphic Inteirval The results of the conodont study from core CA—179 are presented in Figure 18, The number of conodont elements found in the chosen samples ranged from 0 to 135 (see Table B of the Appendix). The small number of cono- donts present is most likely a reflection on the amount of sample available. Only one-half of the core (approximately 250 gras) was dissolved. Of the identified conodonts, Plectodina furcata and Phragmodus undatus are the most abundant and are of major importance to this study. Oulodus oregonia, Aphelognathus (Ozarkodina) polita. Bryantodina abrupta and Belodina compressa were also identified but no quantitative analysis of these conodonts were made. The ranges of these species within the core are plotted next to the ratio of Phragmodus to Plectodina plus Phr agmo du s (Fig. 18). Comparison of the ranges of these species with the range charts of Sweet and Bergstrom (l97l) places this core within their Fauna Zones 9* 10* and 11, which correlates biostratigraphically to their composite Lexington—Point Pleasant—Kope section of Ohio, Indiana and Kentucky, Examination of the relative abundances of Phrag modus to Plectodina plus Phragmodus (Fig. 18) shows that Phragmodus, the relatively restricted deep-water conodont (Seddon and Sweet, 1966), appears abundant in two general 103 Figure 18. Results of the conodont analysis of* core no. CA—179# Percent scale at the top is based on the relative abundance of Phragmodus/ Phargmodus + Plectodina. Horizontal line between the two bentonites marks the contact between the Tyrone Limestone and the Curdsville Member of the Lexington Limestone. 104 O 10 20 30 40 50 60 70 80 90 IO O Bentonite Bentonite 15.22 meters (50ft.) Vertical Scale 105 positions within the cone. These are located approximate ly at 2 m and at 8 m above the base of the core and again in the upper part of the core 103 ni above the base. Approximately 5 above the base of the core is the contact between the Tyrone Formation and the Curdsville Limestone Member of the Lexington Limestone. Tyrone sedi ments were deposited in quiet, shallow intertidal waters and Curdsville sediments were deposited in agitated, deeper water (inner infralittoral) (Cressman, 1973)# The question arises, does this change in water depth also represent a relatively brief period in time and can the fluctuation in conodont species be used to represent a time surface? Associated with the lower peaks in core CA-179 are two bentonites which can be traced throughout the stud}^ area. Bentonites of this nature are isochronous. The lowermost peak lies between the two bentonites which further suggests that it may be used to indicate an iso chronous or nearly isochronous surface if this peak can be traced over a relatively wide area. Other evidence exists throughout the study area that support Seddon and Sweet’s (1966) hypothesis that the relative changes in abundance of Phragmo du s and Plectodina can be used to indicate nearly isochronous horizons. The Pencil Cave bentonite is found in the upper part of the Tyrone Limestone throughout the study area which suggests that the upper part of the Tyrone is isochronous. Near and 106 beyond the Kentucky River south, and southeast of Lexington, the Curdsville Limestone rests directly on the Mud Cave bentonite, the uppermost bentonite of the Tyrone Limestone (Cressman, 1973)* Cressman (1973) has further shown by isopaching the thickness between the Pencil Cave and Mud Cave bentonites that the Curdsville Limestone is not any where time equivalent to the Tyrone limestone. This fur ther suggests that the top of the Tyrone is isochronous. Examination of the Phragmodus/P1ectodina ratio at the type section of the Lexington Limestone in Frankfort, taken from Sweet, Harper, and Zlatkin (197^0 (Fig# 19) reveals that the relative deeper water Phragmo du s conodont was abundant at that time. By observing the high percentage of Phragmodus in Figure 19 at the base of the Curdsville Member in core CA—179 at Frankfort, Kentucky and Clays Ferry, Kentucky, it is highly suggestive that this invasion of the deeper water platform conodont took place over a wide area. Furthermore, the traceable conodont peaks mark the same or nearly the same isochronous surface which is also marked by the traceable bentonite beds which occur throughout the area. Located from 55 ni (180 feet) to 60 m (200 feet) above the top of the Tyrone Limestone in Kentucky is the base of the Brannon Member of the Lexington Limestone. 107 Figure 19- Comparison chart of the results of this study (CA-179) with the Frankfort, Kentucky and Clays Ferry, Kentucky sections of Sweet, Harper and Zlatkin (1974). Percentage scale based on ratio of Phragmodus/Phragmodus + Plectodina = base of time-stratigraphic interval = top of time—stratigraphic interval Cores are arranged according to their approximate geographic locations* Using core CA-179 as a base point and southern most point, Frankfort, Kentucky lies to the northwest, with Clays Ferry, Kentucky lying to the northeast* 108 109 9 10 go 10 40 SO 60 TO 80 90 100 0 1 0 30 3040 SOW TO SO 90100 0 10 20 SO 40 30 SO TO B .O 9.0190 _ CLAYS FERRYFm Nicholas Member - s v . r ' • — . _ MHIenburg *>, Devil Hollow " T L — Tanglewood Member____ —Brannon Member____ \ N -IT ' s N ' ' T r - \ \ .Macedonia < Bed -Logana \ Member N \ \ \ \ \ -Curdeville— Member FRANKFORT, KENTUCKY T " - CLAYS FERRY Fm Grier Member . Tanglewood Member____ — Brannon Mem ber. CLAYS FERRY, KENTUCKY Curdsville Tyrone Vertical Seal* CA-179 Examination of the Phragmodus/Plectodina ratio at Frankfort and. at Frankfort and Clays Ferry, Kentucky (Fig. 19) shows a distinct peak in the conodont curves at the base of the Brannon Member in both areas. Interestingly enough, a thin bentonite is located above the base of the Brannon Member in one locality in the Versailles quadrangle, one locality in the Lexington West quadrangle, and in three localities in the Coletown quadrangle (Black, Cressman, and MacQuown, 1965* p. 21) . This suggests that the base of the Brannon Member is isochronous which further sug gests that the conodont peaks mark this nearly isochronous surface. Found in core CA—27 in southern Kentucky is a thin bentonite which appears 58 m (190 feet) above the top of the Tyrone Limestone. It is proposed that this is the same bentonite that is found within the base of the Bran non Member, since all of the bentonites occur within 55 ra (180 feet) to 60 m (200 feet) above the Tyrone Limestone. Using the bentonites at the top of the Tyrone Lime stone and those found at the base of the Brannon Member or approximately 60 m (200 feet) above the Tyrone Limestone defines an approximate time—stratigraphic interval. This study, however, is interested in the rocks lying immediately above this interval. It is obvious that the base of the overlying time—stratigraphic interval is defined by the bentonites and the conodont peaks which are 110 located approximately 60 m above the Tyrone — Curdsville contact. The conodont curve in core CA-179 shows no fluctuation at tbis level. Plectodina is present but not Phragmodus. The lithology present at tliis depth is sub class 1—1 and 1-2. Inasmuch as sediments that comprise these rocks were deposited in shallow, agitated waters, one would not expect any Phragmodus to be present. Litho — stratigraphically the rocks present at this level in core CA—179 correlate to similar rocks in core CA—27 where the bentonite is located. The upper limit of the time—stratigraphic interval is determined by fluctuations in the Phragmodus/Plectodina curves. The large peak at 103 m core CA—179 matches well with the peak of Sweet, Harper and Zlatkin (1974) located at 70 m (230 feet) above the base of their Clays Ferry section (Fig. 19)* The general shape of the entire curves matches well when comparing these two sections. The resultant time—stratigraphic packet chosen gives a lithologic thickness of 47 m (154 feet) in the southern province (CA—179 southward), and a lithologic thickness of approximately 39*6 m (130 feet) in the northern area (around the Lexington dome). Cores CA-55* DU—3* and CA—34, located between these two areas, have interpolated lith— ologic thicknesses of approximately 45 m (148 feet). This change in lithologic thickness represents a change in slope of approximately one minute of one degree over the entire 111 study area. The necessity for further conodont studies in the area to confirm these peaks is recommended because of the small samples which were available for studying. Statistical Procedures Relative mechanical energy' and relative water depth scales were erected among the rock classes and numerical values were assigned to each class or subclass of limestone. Over the chosen time-stratigraphic interval the total thickness of each class or subclass of limestone in each core was tabulated and multiplied by the assigned energy or depth value. The resultant number was then divided by the total thickness of the time—stratigraphic interval. Thus X where X a x n t 112 n S a-x, + a0x0 + . . . . . . . . . a x 3. 1 2 2 n n 1=1 --------------------- = Relative mechanical energy or relative water depth for the entire core at the deposition site, = class or subclass of limestone thickness with in the time—stratigraphic interval, = the assigned mechanical energy value or rela tive depth value, = the number of classes or subclasses of lime stones present within the core. = total thickness of time—stratigraphic interval Relative mechanical energy and relative water depth values were generated for each core over the desired time— stratigraphic interval. A SYMAP contouring program pro vided by John McDonald, Department of Geography, Univer sity of Southern California, was used to contour these generated values over the study area. In addition this SYMAP program was used to contour isopach values and con struct a structural contour map. Isometric diagrams were generated from the SYMAP program. Table C of the Appendix lists the determined mechanical energy and water depth values for each of the cores during the chosen time interval. The SYMAP contour maps and isometric diagrams are presented and interpreted in the discussion section. Tally matrices were constructed and examined for each core logged over the chosen time interval. Three large summation matrices were compiled from the original tally matrices from the cores taken in the northern, central and southern provinces within the study area. The purpose of doing this is to observe changes in lithologies on a microfacies scale which should also be the same as those observed on the megascopic and regional scale. Also, applying Walther's law, these vertical microfacies changes should in addition reflect lateral changes which exist regionally. This procedure involved setting up a matrix 113 with, all the possible combinations of limestone classes which appeared in each core. The ordinate (Y-axis) is designated as the "from” rock class or the combination of classes which appeared in a 1 foot interval. The abscissa (X — axis) represents the "to" rock class or class com binations which were present in the overlying foot of core. Thus by continuing vertically through a core a continuous record of rock associations is produced. Examining many cores by this method should produce strong associations be tween the classes of limestones from which a depositional model based on fractions of a foot (centimeters) can be constructed. This, in turn, can be tested against large- scale regional facies changes. Lithostratigraphy and the Sediment Deposition Model The stratigraphic cross-sections that will be dis cussed are presented in the fold-out map (Fig. 20) located in the pocket attached to the back cover. The locations of the cross-sections are shown in Figure 1. The strati graphic profiles are generalized and the lithology depicted represents the major lithologic facies that was present at each foot logged. In order that oversimplification does not inhibit correct interpretations, tally matrices for the north, central and southern provinces in the study area will be examined first. This will make the reader aware of 114 strong associations which exist between facies. Xn turn, the stratigraphic cross-sections in each, of these areas will be examined and a depositional model conformable to both the microfacies and regional facies will be postulated and tested for each of the three provinces. Lastly, an integrated summary of the paleogeographic and sedi- mentologic conditions which existed over the entire study area will be presented. The differing stratigraphic nomenclatures which have been erected for these lithologies in Kentucky and Tennes see will not be used because of obvious overlapping and interfingering relationships which may exist over this large area. Each system appears applicable in their re spective areas and no new or modified formational or member names will be suggested. Northern Province Tally matrix Xn the northern province, defined by those cores within and immediately on and surrounding the Lexington Dome, the tally matrix (Table 5) reveals strong associa tions between limestone classes 1 and 2, with the strong est of these being between subclass 1—3 and class 2, the fine grainstone facies and shaley mudstone facies, re spectively. These two facies are almost always associated together within a one foot interval of logged core. Sub- 115 Table 5 Tally matrix for the northern province. Strong associations appear as darker numbers. 116 CLASS To _ roro ror\3 0 JO J ^ J ktn ^ L j ^ o o j i v o j - f* cn o> £ j o j no 04 - L o j r o o j - L u i C T > ro o j ^ cn o> o j - L cm cr> _L < T > o i o> <r> CLASS u _ H From 3 4 I l l 4 I I 15 I 12 I (I-I) 8 I 2 2 11 (1-2) I 58 8 2 14 9 i (1-3) I I I 2 I I 3 4 5 6 ( I - 1 ) - ( 1 - 2 ) (I-I)-(I-3) (1 -0-2 (1-0-3 0-0-4 (1-2)-(I-3) (I-2 )-2 (1-2)-3 (l-2)-4 (1-2)-5 ( 1 -2)-6 ( I - 3 ) -2 1 3 2 ( I -3) -3 f l -3)-4 ( I -3)-5 (l-3)-6 2.3 2-4 2-5 2-6 3-4 3-6 4-5 4-6 5-6 Column 17 5 O I 52 77 28 87 91 0 0 2 0 2 4 Totals 99 4 148 0 26 I 17 0 7 126 16 5 21 0 0 1 3 2 9 1 2 Row Totals 16 95 7 4 0 99 1 6 2 201 4 5 1 5 145 I 1 1 0 2 17 3 4 2 3 4 6 7 1 56 1 3 5 3 1 1 5 1 4 2 27 2 4 5 37 1 7 14 72 1 2 3 8 4 3 5 3 3 27 2 3 2 5 17 1 6 2 8 I 724 6 1 I I 2 86 1 22 3 3 7 37 2 1 8 1 97 1 1 2 2 7 0 2 4 4 15 3 6 15 3 1 63 1 1 1 2 1 128 0 5 1 1 1 1 2 3 2 16 1 1 2 1 1 3 5 0 2 2 2 2 3 3 1 2 17 5 14 117 classes 1—1 and 1—2 appear together often within the cores and suggest along with the petrologic evidences that dif ferences between these two are relatively minor and they may be treated as one facies. The final strong associa tion exists between the wackestone facies (class k) and the grainstone facies (subclasses 1—1 and 1—2). The shaley mudstone facies (class 2) and the wackestone facies (class are not strongly associated. Classes 3* 5* and 6 are minor in occurrence with the time—stratigraphic interval studied. Class 5 and class 6 when they do occur, however, are associated together. Li tho s t r a t i graphy Examination of the cross-sections A—A* and B—B 1 (Fig. 20) in the northern province indicates that the same general relationships among the various facies observed in the transitional probability matrix are valid on a region al scale, both vertically through the cores and laterally along chosen time lines. For example, it can be seen that the shaley mudstone facies (class 2) changes laterally and vertically into class 1 grainstone or fine grainstone facies or vice versa. Likewise, class k wackestones change laterally and vertically into class 1 grainstones. Thickness and lateral extent Xn the northernmost profile (A-Af) during the first 118 half of tlie time interval the grainstone facies appear to liave dominated the area, reaching a maximum thickness of approximately 12*5 m (40 feet) in core 196* At the base of cores CA—57 and CA—37 is dominantly the fine grainstone facies and its associated shaley mudstone facies* This unit has a maximum thickness of approximately 12*5 m (40 feet) and appears to thin westward* The upper halves of the cores are dominated by the shaley mudstone facies (class 2)* The base of the time interval in the stratigraphic cross-section B—B * is marked by the presence of the fine grainstone—shaley mudstone facies association* This unit is continuous over almost the entire area, appears to thicken slightly to the west reaching a maximum thickness of 6 m (20 feet) in core l6l, and then thins and vanishes further westward* The grainstone facies is continuous throughout the area and can be divided into two units* The lowermost unit is thickest in the west portion of the section, reaching a thickness of 2k m in core 171* This unit thins eastward and laterally is replaced by the wacke stone facies (class 4)* The uppermost unit appears to have the reverse trend* This unit thickens to the east and laterally along time lines changes into the shaley mudstone facies to the west and wackestone facies to the east* The wackestone facies (class 4) is the dominate unit within most of the cores and reaches a maximum thickness in the 119 east (30 m) * Xt lies between tlie two grainstone units and thins to the west. The mudstone facies is again present lithologically in the upper sections of the cores, but only appears in the western cores during the chosen time interval* Looking at these facies relationships in a north- south profile (F—F 1) and specifically at cores 196, 166, and 153 reveals that the grainstone facies are relatively constant in thickness and extent. The uppermost grain stone unit thins in a northerly direction. The complexly interbedded fine grainstones and shaley mudstones located at the base of the time interval appears to thin both to the north and to the south away from cores 166 and 153* Similarly, class 4 wackestones thin in these same direc tions but more slightly to the south. The dominately shaley mudstones in the upper part of the time interval is thinnest at core 166 and thickens from this locality in both a north and south direction. Sediment depositional model Facies distribution is a result of the complex interaction between biogenic production, sedimentary materials, currents and bathymetry. Xn shallower agitated waters skeletal grains would be sorted, abraded, broken, winnowed and reworked by currents, tidal currents, and fair weather and storm waves, leaving a grain—supported 120 fabric within the sediments. Waters slightly to moderately deeper and somewhat less agitated would most likely be more desirable for biologic productivity depending on the organisms present and for the accumulation of lime mud which would most likely be a product of the breakdown of larger fossil grains by the work of boring algae, bacteria, fungi and burrowing infauna. A wackestone or packestone fabric would most likely result in such an environment. Xn deeper water or topographic lows, below the zone of active biologic production, carbonate muds and terrigenous fine—grained material from other source areas would ac cumulate producing a mud supported texture. Occasionally or periodically coarser—grained sediments normally de posited in the shallower more agitated zones would be washed and winnowed in these deeper water areas. These times of high mechanical energy in relatively deep water may be the result of storms, strong tidal currents, or changes in current speeds and directions. Overturned stromatoporoids have been reported at several localities within the Millersburg and Grier Members of the Lexington Limestone (Cressman, 1973)* Large-scale ripple marks were also observed in the Clays Ferry Formation in this area (Fig. 21). The complex interrelationships between the grain— stones, wackestones and shaley mudstones may also to some extent represent an adjustment by the environment to main- 121 Figure 21. Ripples located, in Clays Ferry Forma tion northwest of Sadieville, Kentucky. Ripples crest alignment is due east- west with, current direction to the upper right of photo (due north). 122 123 tain a balance between biologic productivity, shoaling and sea floor subsidence (Cressman, 1973)* With slow or no subsidence, areas of shoaling banks or bars and areas of high biologic productivity would prograde. The amount of buildup in the high—energy shoal areas would be directly related to the amount of materials that were being pro duced in the biologically active, relatively deeper waters, assuming that the dominant currents were transporting these sediments toward the shoals. If progradation of shoals proceeds at a faster rate than the materials are produced, then deposition on such shoals will slow down until the area where the biologic grains are being produced has in creased sufficiently, either by subsidence or eustatic sea level rise, to provide materials for these relatively shallow water, higher mechanical energy areas. If fast subsidence be the case, then the facies zones would recede landward or to previously existing topographic highs. The relatively high mechanical energy carbonate shoals identified by the grainstone facies in the strati graphic sections were present in the lower half of the time interval and thickest in the western portions of the stratigraphic cross-sections. This unit is directly over- lain or underlain in parts by the relatively deeper water less agitated wackestone facies or fine grainstone-shaley mudstone facies association. The wackestone facies appears to thicken to the east and thin to the north and west. If 124 these wackestone sediments are the source area for the materials that formed the grainstone units and represent the areas of active biologic production, then this environ ment existed extensively in the eastern and southern por tions of the area during this time interval. The shaley mudstones mostly appear in the upper part of the sections and are extensive in the north and eastern portions of the area. This also suggests that the major source for the lithogenous clays and silts found in this facies lies to the north and east. This source area is probably the Ap palachian Mountains which were being built at this time (Bird and Dewey, 1970). The Canadian shield and trans continental arch which was emergent to the north and west during the Middle Ordovician may have contributed some lithogenous materials in the area. It probably was of low relief and its contribution of such sediments would have been minor. The shield, however, may have played an im portant role in determining the oceanic current circulation patterns which existed in this epicontinental sea. Central Province Tally matrix The central province (cores CA—3^-> DU—3 and CA—35) tally matrix (Table 6) shows the same strong associations among limestone classes as in the northern province. Class 1 grainstones and fine grainstone facies are commonly as— 12 5 Table 6 Tally matrix Tor central province. Strong' associations appear as darker numbers• 126 127 CLASS "To" l l P II From 1 ^ wrooj r\3 oj 4^ oj rv> < I > J ^c!nmro(!>J^cnmcM^ino>.£0><*i>m (I-I) (1 -2) ( 1 - 3 ) 2 3 4 5 6 (I-0-0-2) ( I - I ) - 0 - 3 ) 0- 1)-2 ( 1 - 0 - 3 ( 1 - 0 - 4 ( 1 - 2 ) - ( I - 3 ) ( l - 2 ) - 2 ( 1 - 2 ) - 3 CLASS 0|;4 ( l - 2 ) - 6 ( I - 3 ) - 2 f l - 3 ) - 3 ( I - 3 ) -4 ( 1 - 3 ) - 5 ( 1 - 3 ) - 6 2-3 2-4 2-5 2-6 3-4 3-6 4-5 4-6 5-6 Column Totals 2 4 9 25 2 0 46 5 I I I I 2 5 718 6 I 10 7 2 9 I 5 2 4 10 2 2 3 7 1 5 I I 4 1 I I 3 13 15 2 2 I 5 4 28 7 4 7 I I 4 58 39 24 62 1 9 1 3 6 8 7 1 7 6 2 2 72 I 0 3 0 0 0 0 1 1 8 2 0 1 6 5 0 0 0 0 Row Tot a l s 2 9 4 2 3 47 0 0 4 1 9 55 12 38 6 24 8 62 0 0 120 3 2 0 0 0 16 0 0 6 sociated with the class 2 shaley mudstone facies. Sub class 1—1 and 1—2 grainstones are also commonly associated with class h vackestones, Lithostratigraphy The stratigraphic cross—section C—C1 show the same relationships among limestone classes on a regional scale as seen in the transitional probability matrix. Vertically through the cores and laterally along time lines it can be seen that grainstones change to wackestones or shaley mud stones. Thickness and lateral extent At the base of the stratigraphic section in the west and central cores the grainstone facies are present. They are thickest in core DU-3 (approximately 18 ra), and thin westward to approximately 7 m* The grainstone facies are continuous to the east, thin gradually and transgress time lines. In the western and central areas in the lower portions of the cores, the grainstones are intertongued with the shaley mudstones. To the east the grainstones become interbedded with the wackestone facies. This wackestone facies appears to be the dominant lithology to the east in the lower half of the section. Approximately 22 rn of wackestones sediment deposition is recorded in core CA—55* Except for the uppermost bed which is con tinuous and maintains a constant thickness through the en— 128 tire section, the wackestones are generally restricted to the eastern areas where they also apparently thicken. The upper portions of* the cores are dominated by the shaley mud stone facies. This facies is thickest in the west, 33 m of sediment deposition, and thins gradually to the east. The north—south stratigraphic profile F—F 1 shows that all of these facies appear to be traceable and con tinuous in the subsurface with both the northern and southern provinces. Sediment depositional model Xn the lower sections of the cores the relatively shallower water, more mechanically agitated facies appears to have dominated. To the west this facies interfingers with the deeper—water shaley carbonate mudstones and fine grainstones which also dominate the upper half of the time- stratigraphic interval. This deeper—water facies associa tion thins eastward and suggests that the source area for much of the lithogenous materials contained within these rocks may have originated from the west, possibly the Ozark Dome (¥ilson, 1962). Contributions from a northerly or northeasterly source are also possible as suggested by the north—south profile. The fine grainstones associated with the deeper—water lime muds were most likely washed and winnowed into this environment from either the northern or southern provinces or from areas to the east where bio- 129 clastic fragments were more plentiful. The wackestone facies which, probably represents areas of active biologic production appears to have dominated in the eastern areas. The complex interbedding and interfingering between the grainstone and wackestone facies may be the result of biologic production and material supply rates or minor eustatic fluctuations. Xn any case, the shoal build-up occurred in a westerly direction reaching a maximum thick ness in core DU—3 and then decreased further westward. Occasional onlap or offlap, or subsidence produced a change in the environment which was culminated by the final ap pearance of the deeper water facies over the entire area. Southern Province Tally matrix The generated matrix (Table 7) for the southern province shows the same strong associations among the classes of limestones as the northern and central pro vinces. In addition, class 5 and class 6, the restricted carbonate mudstone facies and the restricted wackestone facies, respectively, appear and show a strong association to one another. Lithostratigraphy Thickness and lateral extent. Xn the stratigraphic section D—D 1 the grainstone facies appears to be the major 130 Table 7 Tally matrix for the southern provlnc Strong associations appear as darker numbers. CLASS To' 0 0 0 = & i> i4 £i i\>ro roro 0 1 o j-& > m .11 ^iiiriiiiiiiri L j iii 1 1 1 1 i 1 1 i_ l\j 6 < n o oj m cn£o oj r v > c m oj n o oj - T * oictj ro oj -t> c n m o J-t> cno)^o>oio)a) CLASS 11-- n From Row Totals (l-l) 13 l 8 5 4 3 2 6 1 2 1 46 (1-2) I 28 9 i 4 2 7 1 4 2 59 (1-3) 6 24 2 2 5 1 2 12 7 61 2 1 1 1 2 2 l 9 3 I 1 3 3 5 13 4 6 3 4 30 2 1 4 10 3 3 5 6 1 1 1 80 5 0 6 1 9 10 ( 1 -I)-fl-2) 2 9 1 16 1 3 6 2 2 6 3 51 (1 —0—0—3) 12 4 1 6 6 4 5 1 10 ! 3 \ 45 (l-l)-2 1 1 1 2 749 2 5 11 2 I I 1 93 (1-0-3 1 1 1 1 4 (1-0-4 7 10 4 2 7 28 3 I I 2 4 78 (I-2MI-3) 2 1 3 1 1 4 7 7 2 9 1 37 (l-2)-2 15 3 3 8 4 5 2 421 1 9 3 1 1 77 ( 1 -2)-3 1 13 1 3 18 ( 1 -2)-4 14 1 I I 16 1 2 10 3 5 1 35 3 5 3 92 (1 —2)—5 0 ( 1 -2)-6 1 1 3 1 6 l-3)-2 3 1 7 2 2 5 I 1316 2 2 1 1 1 5 1 71 2 13 1 6 165 (l-3)-3 1 1 2 1 5 ( 1 -3)-4 1 9 3 2 1 5 1 8 4 20 3 57 ( 1 -3)-5 I I 1 12 (l-3)-6 1 1 2-3 1 2-4 1 1 1 12 1 1 3 9 2 31 2-5 0 2-6 1 8 9 3-4 I 1 3-6 0 4-5 0 4-6 1 1 17 19 5-6 2 15 17 Column 44 58 12 0 55 109 80 74 90 5 4 I I 0 1 0 16 Totals 56 9 82 12 44 0 40 17 0 168 58 3 18 I I 0 18 132 lithology present, These grainstones pass vertically and laterally into shaley mudstones (class 2), wackestones (class 4) or fine grainstones (subclass 1—3)* From core CA-66 to core CA-lOO the cross-section changes to a southerly direction* In this area, at the base of the time interval, the grainstone facies passes laterally into class 6 and class 5 limestones* The grainstones are con tinuous throughout the entire stratigraphic section and appear to be divided into a lower and upper unit. The lower unit has a maximum thickness of 15 m, thins eastward where it complexly intertongues with class 2 or class 4 limestones, and to the south where it passes laterally into class 6 limestones. The upper unit appears thickest in the eastern areas (cores CA—169, CA—179» CA—121 and CA—66) where it is approximately 20 m thick. This unit also transects the postulated time lines. The upper and lower grainstone units are separated by a fine grainstone facies unit which is consistent and appears to thicken to the east where it reaches a maximum thickness of approximately 30 m in core CA—121. It thins further eastward and then thick ens southward from core CA—66 to CA-lOO. The wackestone facies interbeds with both the grainstone and fine— grainstone facies and is most abundant in the eastern sections of the stratigraphic profile. The shaley- mudstone facies is present for the most part in the western areas and in the upper sections of the cores. 133 Further southward, stratigraphic cross-section E-E1 shows a similar pattern of sedimentation. At the base of the cores in the west and central areas is the grainstone facies. This facies is consistent, thickens slightly eastward and is interbedded with the wackestone facies. Both facies transect time lines. In the basal portions of cores CA—81 through CA—19 the grainstone facies grades laterally and vertically into the restricted carbonate mudstone and restricted wackestone facies. Moving vertically upward in these eastern section cores, the restricted facies are replaced by the more common facies which exist throughout the area. The shaley mud stone facies is most commonly found in the upper sections of the cores in the western areas. The stratigraphic relationships between these facies in a north—south direction can be suggested from profile F-F* . In the southern province, from core CA-179 and southward during the time stratigraphic interval, the grainstone and wackestone facies are the dominant lithologies. These facies are consistent and traceable through the entire area. The shaley mudstone facies ap pears to be restricted to the northern areas of the southern province. At the base of the time interval re stricted carbonate mudstone and restricted wackestone facies are encountered and apparently become more intense during the time interval to the south and southeast. 134 Sediment depositional model Dunlng the time interval, carbonate shoals appear to have dominated much of this southern area. At the on set of this time interval, these shoals apparently were extensive enough or some structural control was present to restrict oceanic waters and current circulation in the ex treme south and southeast areas of the province. This relatively "restricted" environment was responsible for producing the sediments which comprise class 5 and class 6 limestones. The remainder of the time was dominated with the more "normal" type of marine sedimentation. The sediments that make up the wackestone facies which were responsible for supplying some of the bioclastic fragments to the carbonate shoals (grainstone facies) appear to be more extensive in the eastern regions. The sediments which formed the shaley mudstone facies are present in the north and western areas. These shaley mudstones are also found to the east interbedded with the fine grainstone facies. Regional Paleogeography and Sediment Depositional Model During the lower portion of the time—stratigraphic interval, shallow agitated water sediments appear to have dominated the entire area. Minor fluctuations in water depth, bathymetry, current activity or biologic production 135 created the complex intertonguing and interbedding which exists between facies. In the north, these shoals ac cumulated to greatest thicknesses in the western portions of the study area# Intermediate depth wackestone type sediments accumulated to the east# The central province shoals appear to be thickest in the central area of* the study area# The shoals thin westward where they change facies to deeper—water sediments and interfinger to the east with the intermediate depth sediments that produced the wackestone facies. In the southern province these shallow water mechanically agitated areas were more com plexly interbedded and interfingered with deeper water, less agitated sediments# Construction of shoal areas dur ing this time was sufficient enough to inhibit circulation of epicontinental oceanic waters and currents which result ed in the formation of a restricted environment to the south and southeast* This restricted environment, however, was not present for any considerable length of time# It was subsequently overlain by relatively unrestricted oceanic type sediments which produced the grainstone, fine grainstone, wackestone and shaley mudstone facies. As time proceeded to the close of the time interval, the relatively shallow agitated deposition sites became the accumulation centers for deeper water sediments except for two areas which remained shallow. One area was located 136 in the northern province centering approximately around core 166 and the other was in the southern province extend ing from core CA—179 southward. Xn the northern province relatively deeper water sediments accumulated to the north, east and south of the shoal area* The entire central province also became the deposition site for deeper water sediments. Shallow water sedimentation in the southern province was interrupted in the northern and east ern areas of this province by an environmental change which provided the proper conditions necessary for the ac cumulation of the deeper water, fine grainstone and inter- bedded shaley mudstone facies sediments. As a result of this intermittent invasion of deeper water sediments in these areas along with other deep water sediments which originated from the west, accumulation centers for deeper water sediments in the southern province during the upper half of the time interval appear to be present to the west, north and east of the shoal environment. 137 DISCUSSION A question that now presents itself is whether or not the petrologic or stratigraphic evidence introduced can be used to determine the presence or absence of the Cincinnati arch during the time interval examined. If* the arch was present, what shape or form did it possess and how is this reflected in carbonate lithosomes? If the arch was not present, was there some other structural or topographic features present, specifically the Lexington and Nashville domes or precursors of these domes or pre dominant faults which may in some way have dictated or partially dictated the sediment distribution patterns and facies relationships presented here. In order to help resolve these questions, a rela tive mechanical energy index scale and two relative depth index scales were constructed based on the petrographic and stratigraphic evidence. Figure 22 shows the relative mechanical energy and depth values assigned to each lime stone class or subclass. The values on the scales are purely arbitrary and are ordinal in measurement. Two depth scales are presented for the following reason. Field and core analyses show a close association among subclass 138 Figure 22* Relative mechanical energy and depth. values assigned to each class or sub class of limestones* 139 RELATIVE ENERGY INDEX Class or Subclass l-l,l-2 1-3 1 1 3 1 4,6 1 2,5 1 Energy Value 5 0 4 0 High Energy 3 0 2 0 10 Low Enerqv RELATIVE DEPTH INDEX1 CASE1 Class or I- Subclass - 1 ,1-2,5 6 L 1 3 I 4 I 1-3,2 ___1 Depth Value 10 2 0 Shallow Water 3 0 4 0 5 0 Deep Water RELATIVE DEPTH INDEX: CASE 2 Class or l-l,l-2,5 1-3,6 Subclass t 3 I 4 1 2 _J Depth Value 10 2 0 Shallow Water 3 0 4 0 5 0 Deep Water 140 1—3 and class 2 limestones# The sediments which comprise subclass 1—3 fine grainstones suggest deposition under relatively high mechanical energy conditions whereas the sediments which make up class 2 shaley (argillaceous) mud stones suggest being deposited under low mechanical energy. However, since they were deposited alternately within centimeters of* each other in the examined cores, the sediments which comprise these lithologies were ob viously deposited in much the same water depths# Class 2 shaley mudstone sediments suggest being deposited in the relatively deepest waters and are assigned a deep water value# Hence, subclass 1—3 is also assigned a similar value in case 1# The Tine grainstone facies is also found associated with the grainstone (subclass 1—1 and 1—2)# The sediments comprising this facies suggest being deposit ed in relatively shallow waters. In case 2, subclass 1—3 is assigned a value which represents slightly deeper water than the grainstone facies based on the petrologic evi dences previously mentioned. By presenting the hypotheti cal extremes which are possible, one may examine the re sultant maps and determine if any significant differences exist. The !ISYMAP! I contour maps generated from these as signed mechanical energy and depth values (case 1 and case 2) are presented in Figures 23, 24, and 25, respectively. l4l Figure 23* Relative mechanical energy contour map# Rectangle encloses the area of* the map to which, discussion pertains# The area outside of* the rectangle computer generated# / (Lexington ; Dome Nashville / Dome 143 Figure 2k, Relative water depth contour maps Case 1. Rectangle encloses the area of the map to which discussion pertains. The area outside of the rectangle is computer generated. Ikk Lexington Dome ** Nashville Dome 145 Figure 25# Relative water depth contour map: Case 2. Rectangle encloses the area of* the map to which discussion pertains. The area outside of the rectangle is computer generated. 146 f Lexington /Dome ( 4, i e i ? e - Nashville / D o m e 147 Examination of the relative mechanical energy and depth maps shows that the contour lines in the extreme north and central areas transect the present-day arch axis at very high angles. Relative mechanical energy and depth contours also transect the arch axis in the southern area but are not generally at such high angles. It ap pears from these contour trends that an arch structure did not influence mechanical energy or depth conditions in these areas. Therefore, it seems unlikely that the con tinuous arch form that exists today was present during late Middle and early Late Ordovician time. Xt is interesting to note that relatively shallow water higher energy limestones are found in the north- central and southern areas, respectively, and appear to hinge on the present-day arch axis. Since a continuous arch seems unlikely, let us turn our attention to the question of whether the Lexington and/or Nashville domes or some precursors to these domes were present during this time • The north—central (Lexington dome area) shoal en vironment is surrounded by relatively deeper less mechani cally agitated sediments to the north, east and south. The higher energy shallow water environment projected to the west is computer generated and because of the laclc of control points should be disregarded. However, it is in teresting to note that Hrabar, Cressman and Potter (l97l) 148 show a shoal projecting west-northvest across the Lexing ton dome area to Frankfort, Kentucky within the Tanglewood and Millersburg Members of the Lexington Limestone Forma tion. It is possible that these deeper less agitated water areas surrounding the northern shoal environment may be the result of subsidence due to sediments being washed from higher energy shallow submarine environments into these peripheral topographic lows. Certainly the close association of the fine—grainstone facies and the shaley (argillaceous) mudstone facies indicate that shallower water, more mechanically agitated sediments were periodi cally winnowed and washed into deeper, quieter waters. Cross—bed determinations in the Tanglewood Limestone Member in this area indicate dominant paleo—current directions to the southwest (170°) and northeast (37°) (Ilrabar, Cressman and Potter, 197l)* Since the Tanglewood Limestone Member is the stratigraphically defined dominant unit present dur ing this time interval in the northern area, these cross- bed directions further suggest transport of sediments from the shoal area into deeper water environments. Ripple marks have also been observed (Fig. 2l) northwest of Sadie- ville, Kentucky within the Clays Ferry Formation (inter bedded grainstones, fine grainstones and shaley mudstones). The ripple crests trend in an east-west direction and indicate current movement to the north or away from the shoal areas. 149 In tliis northern area structural control may be In volved in producing this shoal environment or subsidence in the adjacent areas. Ettensohn and Dever (1975) state that the north—south Waverly arch (a branch of the Cincin nati arch) was active to the northeast of this area in Cambrian and early Ordovician time. Webb (1969) reports that both the Kentucky River and Xrvine—Paint Creek Fault zones were active in Cambrian time. Cressman (1973) post ulates that slight movement along these faults may have caused subsidence. More important to this study is the movement which occurred on the north—south trending West Hickman—Bryan Station faults. At least 2,000 feet of move ment occurred during the deposition of the Early Cambrian basal conglomerate (Potstam Megagroup), which is mostly absent from the Lexington dome and approximately 2,000 feet thick on the downdropped side to the east (Bond, 1971)* MacQuown (personal communication) also documents 2,500 feet of an echelon basement displacement in three pair of wells in Kentucky. The thinness of Early Cambrian sedi ments and the absence of the St. Peter Sandstone (Ordovi cian) on the up side of this fault is highly suggestive of some topographic high in early Paleozoic time. This Cam brian growth fault may be the precursor to the Cincinnati arch or the Lexington dome. The shoal axis in the Lexing ton area during our chosen time interval interestingly enough roughly parallels the West Hickman-Bryan Station 150 fault zones (Fig. l). To tlie east on downthrown side of the fault systems are deepen vaten facies. To the west lie the shoal facies. Figunes 26 and 27 ane computen genenated isopach and stnuctunal contoun maps of the study anea fon the chosen time stnatignaphic intenval, nespectively. The isopach map is based on the thickness detenmined by the conodont biostnatignaphy and bentonite beds on by the amount of cone which was available fnom the chosen time intenval. All cones in the nonthenn anea wene complete and any deviation fnom the chosen 39*6 m (130 feet) intenval is due eithen to enosion on to sediment not having been de posited. The stnuctunal contoun map is based on the bottom of the time—stnatignaphic intenval. Xn the nonthenn anea the isopach and stnuctunal con toun maps show tnends genenally similan to the nelative mechanical enengy and depth contoun maps. This may be an indication that isopachs noughly nepnesent tnue thickness and thinning may be stnuctunally on topognaphically con— tnolled. Cnessman (1973) a mone detailed isopach map of the entine Lexington Limestone Fonmation shows ne— entnant isopachs which connesponds appnoximately with the tnaces of the Kentucky Riven and Invine—Paint Cneek fault zones• Figunes 28 and 29 ane isometnic computen plots of the nelative mechanical enengy (which neflects paleo— 151 Figure 26. Isopach. contour map of* study area. Contours are in meters. Thicknesses are determined by conodont bio- stratigraphy and bentonite beds, or by the amount of core available from the chosen time stratigraphic interval. Rectangle encloses the area of the map to which discussion pertains. The area outside of the rectangle is computer generated. 152 r i ■5V & o/ Nashville J y Dome i Figure 27. Structural map of tlie base of* the time—stratigraphic interval* Rectangle encloses the area of the map to which discussion pertains* The area outside of the rectangle is computer generated* 15^ Dome 155 Figure 28. Isometric computer plot of* relative mechanical energy contour map. (North is in the foreground, south is toward top of* diagram.) Rectangle encloses the area of* the map to which discussion pertains. The area outside of* the rectangle is computer generated. 156 SNINJlHUHSJUtn M U JO * 00 P . ' IHOiJH* 00 '?■ ' hlUIN* S I1 - J l l l l 1 i 1 1 0 i > j 1 • l i L l l W i Z H J A I I .1.10 5 H J A INIGO ONI X J Ll NI i 0 H .1N . 1 .1A i i H 1.1H 157 Figure 29* Isometric computer plot of structural contour map# Rectangle encloses the area of the map to which, discussion pertains# The area outside of the rectangle is computer generated# 158 159 ‘f T F U C TIj F m L G g'h f Cijf AZIMUTH - i jC X W 11 j T ‘i •- 'j.ijlj Mm1 ' - BASF. OF ALT r TLDF. khF.IGM ! rRR r Tr; F,q^HTC INTERVAL no * 8 hf OF,FI t' 0 F|; > 1C ", T E N T N G M A f bathymetry) and structural contour maps, respectively. Examination of the figures shows that in the northern area the figures coincide almost exactly. This suggests strongly that the paleobathymetry which existed during late Middle and early Late Ordovician time was structural ly controlled. Strong lineations are also observed on both isometric diagrams which parallel the east—west trending Rough Creek fault zone, Kentucky River Fault zone and the north—south trending West Hickman—Bryan Station fault zone. This suggests that these faults were active during this time and that they had a direct influence on the submarine paleobathymetry which existed in the area. This structurally controlled paleobathymetry apparently produced the necessary topographic relief for shallow water, mechanically agitated sediments to accumulate on. During late Middle and early Late Ordovician time this shoal, located in the present-day Lexington dome area, was surrounded on three sides by relatively deeper, less energetic waters where sediments accumulated to greater thicknesses or were subsequently eroded less than in the adjacent shoal area. It is suggested that this structurally controlled shoal area may have been a pre cursor to or an early topographic expression of what was to become the Lexington dome. Shallow water mechanically agitated limestones ap pear to have been deposited in the southern portions of 160 the study area also* These shoal environments are located north of the Nashville dome in the general vicinity of* the present-day arch axis* Relatively deeper water less agitated environments appear to surround these shoals in all directions* Examination of the relative mechanical energy map (Fig. 23) shows a general trend toward higher energies as one approaches the Nashville dome from a northerly direction. This trend is culminated by the rela tively high energy area located approximately 50 km to the northeast of the Nashville dome. Both relative depth maps (Figs. 2k and 25) further suggest that these high energy areas were located in relatively shallow waters. From the southernmost high energy area southward, mechanical energy values appear to decrease. This decrease in mechanical energy is attributed to the increase in restricted rela tively quieter water facies present in this area (see Fig. 20, stratigraphic section E-E1, F-F*). Xt is also in this area that a large divergence in water depth trends takes place. The case 1 relative depth contour map indicates that water depths tend to decrease in a southward direc tion. Case 2 relative depth contour map indicates the opposite trend. Case 1 appears to be the more correct contour map for the following reasons. The individual tally matrices for each of the cores in this questionable area shows overwhelmingly that subclass 1—3* the fine grainstone facies, is almost always associated with class 161 2, the shaley mudstone facies. This suggests that case 1 is a more connect intenpnetation of the true water depth which existed in this anea, Punthen suppont fon case 1 is found by examining cone CA—100, the eastennmost cone in the southenn pnovince and cone CA-19* the southennmost cone on the maps* Stnatignaphically, the thickness of the nelatively deep waten facies (subclass 1—3 and class 2) thins fnom 25 m in cone CA-lOO to 3 m in Cone CA—19 (see stnatignaphic cnoss sections D-D’, E—E 1, Wilson (1962) necneates a negional paleogeognaphy duning the middle Ondovician in centnal Tennessee as being divided into thnee pnovinces. A centnal shoal environment located in the pnesent—day Nashville dome anea and along the axis of the Cincinnati arch, a deepen waten environ ment to the west whene lithogenous sediments wene being intnoduced fnom possibly the Ozark dome anea and a rela tively shallow nestnicted environment to the east that gradually deepened towand the Appalachian mountains* Lithogenous sediments wene also being intnoduced fnom the Appalachian anea to the west. It is the nelatively shal low waten nestnicted envinonment to the east that appeans to be analogous to the nestnicted facies (class 5 and class 6 limestones) found in the southennmost cones at the base of the time intenval. The intnoduction of litho— genous matenials found associated with the lime muds in the deepen waten aneas to the nontheast of the Nashville dome 162 most likely originated from the Appalachian highlands to the east# Accepting the relative depth contour map, case 1, as being more representative of true depths in the southern area, contour lines suggest that water depths decrease in the direction of the Nashville dome# The structural contours (Fig. 26) are generally parallel or sub—parallel to the depth contours. The isopach map (Fig# 25) Is in general agreement with the mechanical energy contour lines, at least in defining the high energy en vironment northeast of the Nashville dome# Two of the cores, CA—84 and CA—6l located in the southern province, were not recovered completely. The middle and bottom sections, respectively, were missing# These two cores are located west of the arch axis in the densely contoured area# The other two cores, CA—88 and CA—29, located in this same area are complete and the missing upper sections were either eroded away or sediments were not deposited in these places at this time. These two latter cores coin cide nicely with the high energy areas# Also, as the relative mechanical energy decreases to the south, due to facies changing into a quieter environment, isopach values increase as is the case in all directions away from these shoals # Comparison of the isometric diagrams (Figs. 28 and 29) in the southern province shows that the patheobathy— 163 me try (relative mechanical energy) and structural map show no direct correlation. This suggests that the shoal which occurs north and east of the Nashville dome was not pro duced by movement on the dome during late Middle and Early Late Ordovician time. This should not be taken to suggest that the Nashville dome was not present during this time because the depth contours, structural contours and re stricted environments to the east of the dome are sug gestive that a Nashville dome of some topographic ex pression of* what was to become the Nashville dome was pre sent to the southwest during this time interval. The relative mechanical energy contours and the isometric diagrams appear to be useful in helping to delineate shoal areas in the southern province, but because of lithologic facies changes which oppose the general trend of increas ing mechanical energy with decreasing water depth, rela tive mechanical energy contours are not useful in helping to determine if the Nashville dome was or was not present. 16k MODERN DEPOSITIONAL ANALOG Bird and Dewey (l970) suggest that during the middle Ordovician an active island arc system (Taconic Orogony) existed in the present-day Appalachian mountain area. Separating this Ordovician island arc system and the low relief transcontinental arch was an epicontinental sea where intrabasinal shallow water carbonate and litho— geneous sediments accumulated, A possible analogue to the Ordovician paleo- environment which existed in central Kentucky and central Tennessee is Pound off the coast of southeast Asia in the area of the Indonesian Islands, A shallow water marine environment separates the mainland of Asia from an active volcanic chain of islands to the south. In fact, the geographic location of this modern analog (relative to the equator) is almost identical to the geographic position of the North American continent as determined by the virtual geomagnetic pole for the Ordovician (Collinson and Run corn, i960), The paleolatitudes determined for the Ordovician place the eastern United States in the southern hemisphere in the zone of the prevailing easterly trade winds, 165 Xn the present day Indonesian area monsoon winds are responsible for producing and reversing oceanic cur rent patterns in a seasonal basis (Defant, 1961)* The reversal of current directions in this shallow water marine environment may be capable of producing a record in the sediments which would show a bimodal current direction. It is possible that some of the bimodal cross beds observed in the Tanglewood member of the Lexington Limestone Formation may have been produced in a similar fashion. Some of the Tanglewood crossbeds appear as dis tinct units with overlying and underlying beds showing opposite directions. Hrabar, Cressman and Potter (l97l) suggest that reversing tidal currents produced the ob served bimodal crossbeds. It is also possible that seasonal changes in current directions produced by monsoon winds may have similar results. These seasonal changes in current directions may also be responsible for produc ing shallow water upwelling zones which may account for the high amounts of phosphate which occur in Middle Ordovician limestones in central Kentucky and central Tennessee as reported by Cressman (1973)# 166 CONCLUDING REMARKS The following statements are presented to summarize tlie results and conclusions of* this study. 1. Limestones in the study area can be divided into six major classes, each of which suggests a different environment of deposition. 2. Stratigraphically the limestone classes appear ing in central Kentucky can be correlated through the subsurface to similar rocks in central Tennessee. Local lithostratigraphic relationships among the classes of limestones can also be traced through the subsurface. 3* A time—stratigraphic interval is defined within this study area. The base of this interval is defined by the presence of a bentonite bed which commonly occurs approximately 200 feet above the top of the Tyrone Limestone. The upper limit of the time—stratigraphic interval is defined by the relative abundances of deep— to-shallow water platform conodonts, represent ed by Phragmodus and Plectodina. respectively. Bentonite beds are present in some areas where 167 fluctuations in the relative abundances of the conodont elements are also observed. This suggests that these fluctuations represent an isochronous or nearly isochronous surface. 4. Limestone class associations on a microfacies scale show similar relationships and trends that are encountered on a regional scale, both vertically and horizontally throughout the cores. 5* Relative mechanical energy and relative depth contour maps based on microfacies measurements appear to be useful along with stratigraphic and petrologic evidences in interpreting regional paleoenvironments and paleogeography. Based on the above conclusions the following paleo— environmental and paleogeographical interpretations are suggested. 1. No continuous Cincinnati arch structure was present during late Middle and early Late Ordovician time in the study area. 2. A shoal area in the north, in the area of the present-day Lexington dome structure, surround ed by deeper water environments to the north, east and south was present and is highly sugges tive that the Lexington dome or some precursor to this dome was present at this time. Paleo— 168 bathymetric contours roughly parallel east-west and north—south trending normal faults which are present in the Lexington area* This sug gests that movement along these faults may have been responsible for creating the bathymetric relief necessary for the shoal environment to form on* Gradual shallowing of water and thinning of deep water facies in the general direction of the Nashville dome also suggests that the Nashville dome or some submarine topographic expression of what was to become the dome was present during this time* During this time interval, shoal environments were present north—northeast of the present- day Nashville dome* Relatively deeper water, less agitated environments were present to the north, east and west of this shoal* To the south of the shoal area or east of the Nashville dome was located a relatively restricted en vironment which lasted for only a short time into the time stratigraphic interval* Since a continuous arch structure was unlikely and fault movement did not appear to control any of the sediment distribution patterns, then either doming to the south of the shoal or sub— sidence of* the adjacent basins may have produced the elevated submarine topography necessary for shallow water agitated sediments to accumulate on, Restriction of* normal epicontinental sea waters by extensive shoaling or doming possibly created the proper conditions necessary for the accumulation of* sediments which lithif*ied to form the restricted facies limestones found east of the present-day dome structure. This further suggests that the Nashville dome or some precursor to the dome was present during this geologic time interval. 170 :PEEENCES CITED 171 REFERENCES CITED Alberstadt, L. P. , 1973* Depositional environments and the origin of the fine-grained limestones of the Bigby— Canon Formation (Middle Ordovician), Central Basin, Tennessee: Jour. Sed, Petrology, v. 43, no. 3, P. 621-633. Bathurst, R. G. C., 1966, Boring algae, micrite envelopes and lithification of mo11nscan biosparites: Jour. Geology, v. 5, p. 15-31. ________, 1971» Carbonate sediments and their diagenesis, Elsevier, Amsterdam, London, New York, 620 p. Bayley, R. ¥. and J. R. Muehlberger, compilers, 1968, Basement rock map of the United States (exclusive of Alaska and Hawaii): Washington, U. S. Geol. Survey, 2 sheets, scale 1:2,500,000. Bergstrom, S. M. and ¥. C. Sweet, 1966, Conodonts from the Lexington Limestone (Middle Ordovician) of Kentucky and its lateral equivalents in Ohio and Indiana: Bulls. Amer. Paleontol. , v. 50 (229), p. 271-441. ________, 1971, Conodont biostratigraphy of the Middle and Upper Ordovician of Europe and eastern North America: Geol. Soc. America, Memoir 127, p. 83—l6l. Bird, J* and J. F. Dewey, 1970, Lithosphere plate- continental margin tectonics and the evolution of the appalachian orogen: Geol. Soc. America Bull., v. 81, p. 1031-1060. Black, D. F. B., 1964, Geologic map of the Versailles quadrangle, Kentucky: U. S. Geol. Survey Geol. Quad. Map 32 5. Black, D. F. B., E. R. Cressman, and W. C. MacQuown, Jr., 1965, The Lexington Limestone (Middle Ordovician) of central Kentucky: U. S. Geol. Survey Bull. 1224-C, p. 29. 172 Black, D. F. B. and W. C. MacQuown, Jr. , 1965* Litho- stratigraphy of the Ordovician Lexington Limestone and Clays Fenny Fonmation of the centnal Bluegnass anea nean Lexington, Kentucky, in Geol. Soc. Kentucky, Ann. Spning Field Conf. Guidebook: Kentucky Geol. Sunvey, 1965, p. 7-43. Black, D. F. B., 1967* Geologic map of the Coletown quadnangle, east—centnal Kentucky: U. S. Geol. Survey Geol, Quad. Map GQ—644. ________, 1968, Geologic map of the Fond quadnangle, centnal Kentucky: U. S. Geol. Sunvey Quad. Map GQ-764. Bond, D. C., et al., 1971* Possible futune petnoleum potential of negion 9-—Illinois Basin, Cincinnati Anch and nonthenn Mississippi Embayment: Amen. Assoc. Petnoleum Geologists Mem. 15* v. 2, p. II65—1218. Bnaun, M. and G. M. Fniedman, 1969* Canbonate litho- facies and envinonraents of the Tnibes Hill Fonmation (Lower Ondovician) of the Mohawk Valley, New Yonk: Joun. Sed., Petrology, v. 39* P* 113-135* Collinson, D. ¥. and S. K. Runconn, i960, Polan wandening and continental dnift; evidence fnom paleomagnetic obsenvations in the United States: Geol, Soc. Amenica Bull., v. 71* P* 915-958. Cnessman, E. R., 1964, Geologic map of the Tyrone quad nangle , Kentucky: U. S. Geol. Sunvey Geol. Quad. Map GQ-303. ________ , 1965* Geologic map of the Keene quadnangle, centnal Kentucky: U. S. Geol. Sunvey Geol. Quad. Map GQ-440. ________, 1967* Geologic map of the Georgetown quadnangle, Kentucky: U. S. Geol. Sunvey Geol. Quad. Map GQ—605* . 1968, Geologic map of the Salvisa quadnangle, centnal Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ-76O. Cnessman, E. R. and S. V. Hnaban, 1970* Geologic map of the ¥ilmone quadnangle, centnal Kentucky: U. S. Geol. Sunvey Geol. Quad. Map GQ—847* 173 Cressman, E. R. and O. L. Karklins, 19709 Lithology and fauna of' the Lexington Limestone (Ordovician) of* central Kentucky, in Southeastern Section Geol. Soc. America, Guidebook for field trips: Kentucky Geol. Survey and Univ. of Kentucky, p. 17—28. Cressman, E. R., 1973* Lithostratigraphy and depositional environments of the Lexington Limestone (Ordovician) of central Kentucky: Geol. Survey Professional Paper 768. Defant, A., 1961, Physical Oceanography: London: Pergamon Press, v. X and XX. Deffeyes, K. S., F. J. Lucia, and P. K. Weyl, 1963, Dolo- mitization: observations on the island of Bonaire, Netherlands Antilles, Science, v. 143, no. 3607* p. 678-679. Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture: in ¥. E. Ham (ed.), Classification of carbonate rocks: Am. Assoc. Petroleum Geologists, Mem. 1, p. 108—121. Ethington, R. L. and D. L. Clark, 1971, Lower Ordovician conodonts in North America: Geol. Soc. America Memoir 127, p. 63—82. Ettensohn, F. R. and G. R. Dever, Jr., 1973, Tectonic control of carbonate sedimentation in the Newman group (Middle and Late Mississippian) Northeastern Kentucky, AAPG—SEPM Annual meeting abstracts. Folk, R. L., 1939, Practical petrographic classification of limestones: Am. Assoc. Petroleum Geologists Bull., v. 43, P. 1-38. ________, 1962, Spectral subdivision of limestone types, in ¥. E. Ham (ed,), Classification of carbonate rocks, a symposium: Am. Assoc. Petroleum Geologists Mem. 1, p. 62-84. ________ , 1963, Petrology of Sedimentary Rocks: Austin, Texas: Hemphill*s, 139 p. Ford, J* P., 1967, Cincinnatian geology in southwest Hamilton County, Ohio: Am. Assoc. Petroleum Geologists Bull., v. 51, P* 918-936. 174 Freeman, L. B. , 1949, Regional aspects of Cambrian and Ordovician subsurface stratigraphy in Kentucky: Amer. Assoc. Petroleum Geologists Bull., v. 33, no. 10, p. 1655-1681. ________ , 1951, Regional aspects of Silurian and Devonian subsurface stratigraphy in Kentucky: Kentucky Geol. Survey, ser. 9, no. 6, 565 P* ________, 1951, Regional aspects of Silurian and Devonian subsurface stratigraphy in Kentucky: Amer. Assoc. Petroleum Geologists Bull., v. 35, no. 1, p. l-6l. Friedman, G. M., 1959, Identification of carbonate minerals by staining: Jour. Sed. Petrology, v. 29, P. 87-97. Gauri, K. L., A. V. Noland, and B. Moore, 1969, Structural ly deformed Late Ordovician to Early Silurian strata in north-central Kentucky and southeastern Indiana: Geol. Soc. America Bull., v. 80, p. 1881—1886. Ginsburg, R. N*, 1956, Environmental relationships of grain size and constituent particles in some south Florida carbonate sediments: Am. Assoc. Petroleum Geologists Bull. 40, p. 2384—2427* ________ , 1957, Early diagenesis and lithification of shallow—water carbonate sediments in south Florida, in R. J. LeBlanc and J. C. Breeding (ejds. ) , Regional aspects of carbonate deposition: Soc. Econ. Paleont ologists and Mineralogists Spec. Pub. 5, 178 p. Greene, R. C., 1966, Geologic map of the Valley View Quadrangle, central Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ-470. G.S.A. Rock Color Chart: The Geological Society of America, 1970* Gutstadt, A. M., 1958, Upper Ordovician stratigraphy in Eastern Interior region: Am. Assoc. Petroleum Geologists Bull., v. 42, p. 513-547* Hayes, C. W. and E. O. Ulrich, 1903, Description of the Columbia quadrangle, Tennessee: U. S. Geol. Society, G Atlas, Columbia folio, no. 95* 6 p., maps. 175 Hrabar, S. V., E. R. Cressman, and P. E. Potter, 1971, Crossbedding of the Tanglewood Limestone member of the Lexington Limestone (Ordovician) of the Bluegrass region of Kentucky, B.Y.U. Geology studies, vol. 18, no. 1, p. 99-114. Tiling, L. V., A. J. Wells, and J. C. M. Taylor, 1965, Penecontemporary dolomite in the Persian Gulf, in L. C. Pray and R. C. Murray (eds♦). Dolomitization and limestone diagenesis: Soc. Paleontologists and Mineralogists Spec. Pub. 13, P* 69—111* Kanizay, S. P. and E. R. Cressman, 1967, Geologic map of the Centerville quadrangle, central Kentucky: U. S. Geol. Survey Geol. Quad* Map GQ—653* Klement, K. W. and D. P. Toomey, 1967, Role of blue—green algae Giruvanella in skeletal grain destruction and lime mud formation in the Lower Ordovician of West Texas: Jour. Sed. Petrology, v. 37, P* 1045—1031* Laporte, L. F., 1969, Recognition of a transgressive carbonate sequence within an epeiric sea— Helderberg Group (Lower Devonian) of New York state, in G. M. Friedman (ed.), Depositional environments in carbonate rocks: Soc. Econ. Paleontologists and Mineralogists Spec. Pub. 14, p. 98—119* Lindstrom, Maurits, 1971, Lower Ordovician conodonts of Europe: Geol. Soc. America Memoir 127, P* 21—61. Lobo, C. F. and R. H* Osborne, 1973, The American Upper Ordovician Standard. XVXXX: Investigation of micrite in typical Cincinnatian limestones by means of scanning electron microscopy: Jour. Sed. Petrology, v. 43, no. 2, p. 478-483* Locke, J*, 1938, Geological report, in W. W. Mather, et al*, Second annual report on the geological survey of the state of Ohio, p. 201—274. Logan, B. W., G. R. Davies, J. F. Read, and D. E. Cebulski, 1970, Carbonate sediments and environments, Shark Bay, Western Australia: Amer. Assoc. Petroleum Geologists Mem. 13, 223 P* Lowenstam, H* A., 1955, Aragonite needles secreted by algae and some sedimentary implications: Jour. Sed. Petrology, v. 25, p. 270-272. 176 Mackey, R. T. , 1972, Lithostratigraphy and deposition environment of tlie Perryville Limestone and related members of the lower Lexington Limestones (Ordovician) of* south-central Kentucky: unpub. M.S. thesis, University of Kentucky, 94 p. MacQuown, ¥. C., Jr., 1967* Factors controlling porosity and permeability in the Curdsville Member of the Lexington Limestone: Univ. Kentucky Water Resources Inst. Research Rept. no. 7* 80 P* ________ , 1968, Geologic map of the Nicholasville quad rangle, Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ-767. ________, 1968, Geologic map of* the Clintonville quadrangle, central Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ-717. MacQuown, W. C., Jr. and E. Dobrovolny, 1968, Geologic map of the Lexington East quadrangle, Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ—683* Margolis, S. and R * W. Rex, 1971* Endolithic algae and micrite envelope formation in Bahamian oolites as re vealed by scanning electron microscope: Geol. Soc. America Bull., v. 82, p. 843—852. Matthews, R. K., 1966, Genesis of recent lime mud in southern British Honduras: Jour. Sed. Petrology, v. 36, p. 428-454. McFarlan, A. C., 1943* Geology of Kentucky: Lexington, Kentucky, Univ. of Kentucky, 531 P* McGuire, W. H. and P. Howell, 1963 * Oil and gas pos sibilities of the Cambrian and Lower Ordovician in Kentucky: Spindletop Research Center, Lexington, Kentucky, prepared for Dept, of Commerce, Common wealth of Kentucky. Medlin, W. L., 1959» The thermal luminescence of dolomite under the cathodoluminoscope: Jour. Chem. Phys., v. 30, p. 451. ________ , 1963* The characteristics of divalent manganese under the cathodoluminoscope: Jour. Opt. Soc. Amer., 53* p. 672. 177 Miller, R # D. , 1967, Geologic map of the Lexington West quadrangle, Kentucky: U. S. Geol* Survey Geol. Quad, Map GQ-600. Newberry, J. S., 1873* Structure of the Cincinnati anti clinal: Rept, Geol. Survey Ohio, v. 1, p. 93-111# Newell, N. D. and J. K. Rigby, 1957* Geological studies on the Great Bahama Bank, in R. J. LeBlanc and J. C. Breeding (eds.). Regional aspects of carbonate deposi tion: Soc. Econ. Paleontologists and Mineralogists Spec. Pub. 5, p. 15-72. Orton, E., 1888, Economic Geology: Rept. Geol. Survey Ohio, v, 6, p. 1—310. Osborne, R. H., 1973* The American Upper Ordovician Standard, XVXI. Areal variation of limestone fre quencies in the Kope and Pairview Formations, Hamilton County, Ohio: Jour. Sedimentary Petrology, v. 43, no. 1, p. 137-1^6. Perkins, R. D. and S. D. Halsey, 1971* Geologic signifi cance of microboring fungi and algae in Carolina Shelf sediments: Jour. Sed. Petrology, v. 4l, p. 843-853# Purdy, E. G., 1963* Recent calcium carbonate facies of the Great Bahama Bank: 2. Sedimentary Facies: Jour. Geol., v. 71, P# 472-497# Raymond, P. E., 1922, Trenton of central Tennessee and Kentucky: Geol. Soc. America Bull., v. 33* P. 571- 585. Rigby, J. K. and W. K. Hamblin, eds., 1972, Recognition of ancient sedimentary environments: Soc. Econ. Paleontologists and Mineralogists Spec. Pub. 16, 340 p. Seddon, G. and W. C. Sweet, 1971* An ecologic model for conodonts: Jour. Paleontology, v. 45, no. 5, p. 869—80. Shinn, E. A., R. N. Ginsburg, and R. M. Lloyd, 1965* Recent supratidal dolomite from Andros Island, Bahamas, in L. C. Pray and R. C. Murray (eds.), Dolomitization and limestone diagenesis: Soc. Econ. Paleontologists and Mineralogists Spec* Pub. 13* p. 112-123. 1 7 8 Shinn, E. A, , 1968, Practical significance of birdseye structures In carbonate nocks: Jour. Sed. Petrology, v. 38, p. 215-223. Simmons, G. C., 1967* Geologic map of* tlie Richmond North, quadrangle, Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ-583. ________ , 1967* Geologic map of the Union City quadrangle, Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ—585# Smith, C. L., 1941, The Great Bahama Bank. 1. General hydrographic and chemical factors. 2. Calcium carbonate precipitation: J. Marine Res. (Sears Found. Marine Res.), v. 3, p. 1-31; 147-189. Tt Sweet, ¥. C. and S. M. Bergstrom, 1971, The American Upper Ordovician Standard, XIIX. A revised time strati graphic classification of North American Upper Middle and Upper Ordovician rocks: Geol. Soc. Amer. Bull. 82, p. 613-628. ________ , 1971, Symposium on conodont biostratigraphy: Geol. Soc. America Mem. 127, 499 p- Sweet, ¥. C., H. Harper, Jr., and D. Zlatkin, 1974, The American Upper Ordovician Standard, XXX. A Middle and Upper Ordovician Reference Standard for the Eastern Cincinnati Region: The Ohio Journal of Science, v. 7^t *10 . 1, p. 47—52. Swinchatt, J. P., 19&5, Significance of constituent com position, texture, and skeletal breakdown in some re cent carbonate sediments: Jour. Sed. Petrology, v. 35, P, 71-90. Scotford, D. M., 1964, Cincinnati Arch: Mineralogical— statistical evidence of post—Ordovician origin; Bull. Am. Assoc. Petroleum Geologists, v. 48, no. 4, p. 427— 436. Terry, R. D. and G. V. Chilingar, 1955, Summary of "Con cerning some additional aids in studying sedimentary formations" by M. S. Shevtsov: Jour. Sed. Petrology, v. 25, no. 3, p. 229. Watkins, J. S., 1962, Pre—Cambrian basement structure and lithology inferred from aeromagnetic and gravity data in eastern Tennessee and southern Kentucky: U. S. Geol. Survey Prof. Paper 450-C, p. C25-C28. 179 Watkins, J. S., 1963, Simple Bouquer gravity map of Kentucky: U. S. Geol* Survey Geophysical Invest. Map GP-421. . 1964, Regional geologic implications of the gravity and. magnetic fields of a part of eastern Tennessee and southern Kentucky: U. S. Geol. Survey Prof. Paper 516—A, P* Al—A17• Webb, E. J., 1969, Geologic history of the Cambrian system in the Appalachian basin: Kentucky Geol. Survey, ser. IO, Spec. Pub. 18, p. 7—15* Weir, G. W. and R. C. Greene, 1965, Clays Ferry Formation (Ordovician), a new map unit in south—central Kentucky: U. S. Geol. Survey Bull. 1224—B. Weiss, M. P. and ¥. C. Sweet, 1961, Contribution of facies analysis to Ordovician history of Cincinnati arch geologic province (abs.): Geol. Soc. America Spec. Paper 68, p. 294. Wilson, C. W. , Jr., 1935* The pre-Chattanooga development of the Nashville Dome: Jour. Geology, v. 43, p. 449— 481. . 1948, The Geology of Nashville, Tennessee: Bull. 33, Division of Geology, Department of Conservation, State of Tennessee. , 1949, Pre—Chattanooga stratigraphy in central Tennessee: Tennessee Div. Geology Bull. 56, 407 p. ________ , 1962, Stratigraphy and geologic history of Middle Ordovician rocks of central Tennessee: Geol. Soc. America Bull., v. 73, P« 481—504. Wolcott, D. E., 1969, Geologic map of the Little Hickman quadrangle, central Kentucky: TJ. S. Geol. Survey Geol. Quad. Map GQ—792. ________ , 1970, Geologic map of the Buckeye quadrangle, central Kentucky: U. S. Geol. Survey Geol. Quad. Map GQ-843. Wolcott, D. E., E. R. Cressman, and J. J. Connor, 1971, Trend surface analysis of the thickness of the High Bridge Group (Middle Ordovician) of central Kentucky and its bearing on the nature of the post—Knox uncon formity: U. S. Geol. Survey Prof. Paper 800—B, p. B25-B33. 180 Young, L. M. , L. C# Fiddler*, and R. W. Jones, 1972, Carbonate facies in Ordovician of northern Arkansas: Amer, Assoc, Petroleum Geologists Bull,, v. $6, P* 68-80. 181 APPENDICES Table A Locations and topographic elevation of diamond drill cones. 183 Core Location Topographic Location Designation_______Carter Coordinate____Elevation____County, State CA-19 2 10 48 875* Van Buren, Tenn CA-81 1 7 44 10301 DeKalb, Tenn, CA-71 16 5 47 1060» Putnam, Tenn, CA-29 18 5 49 990* Putnam, Tenn, CA-43 18 1 43 830* Macon, Tenn, CA-84 11 1 45 605* Jackson, Tenn, CA-88 16 1 49 610* Clay, Tenn, CA-100 12 1 54 1000* Fentress, Tenn. CA-27 9 C 44 854* Monroe, Ky. CA-61 22 C 47 609* Monroe, Ky. CA-169 4 D 50 Cumberland, Ky. CA-179 2 D 50 Cumberland, Ky. CA-121 4 D 52 563* Cumberland, Ky. CA-66 16 D 53 921* Clinton, Ky. CA-55 10 G 55 1051* Russell, Ky. DU-3 5 H 55 Casey, Ky. CA-34 12 I 54 738* Casey, Ky. 152 4 P 60 1060* Jessamine, Ky. 153 6 Q 60 985* Fayette, Ky. 162 14 R 61 1043* Fayette, Ky. 161 4 R 62 1060* Fayette, Ky. 166 24 S 61 1050* Fayette, Ky. Core Location Topographic Location Designation_______Carter Coordinate____Elevation County. State 168 6 S 62 980* Fayette, Ky* 170 22 T 60 990* Fayette, Ky* 171 13 T 60 935* Fayette, Ky* 199 13 R 65 985* Clark, Ky. CA-35 8 R 70 982* Meniffe, Ky. 157 8 T 62 1000* Fayette, Ky. 156 14 U 62 970* Bourbon, Ky. 198 10 W 62 880* Fayette, Ky. 196 22 AA 62 617* Pendleton, Ky. CA-57 14 AA 68 713* Mason, Ky. CA-37 11 Y 70 740* Mason, Ky. 185 Table B Distribution of conodont elements in core CA—179# 186 Percent Number Core Rock Insoluble of Plectc Depth Type Materials Conodonts dina 339.9 13 0 340.0 0 346.9 73 17 348.9 13 350.9 59 18 356.7 68 12 362 2 366.7 61 17 368 13 370 32 3 378 1-2 0.59 31 4 384 22 2 387 107 20+ 393.9 4 2.49 0 407 2-3 3.50 18 1 413 4-3 3.52 4 1 425 4 5.91 36 8 M 00 Percent Phragmodus Ozarkodina Phrag- Plectodina + Apelognathus Oulodus modus Phragmodus Polita Oregonia 0 present 2 10.5 abundant 11 45.83 present 8 30.77 0 0 present present 0 0 abundant 2 16.6 present present 1 7.14 0 0 present 0 0 present 0 0 present 0 0 present 0 0 0 0 0 0 Core Depth Percent Number Rock Insoluble of Plecto- Type Materials Conodonts dina 435 1-1 .65 146 15 449 19 1 457.7 <1-3)-2 4.85 11 5 463.7 4 9.04 9 1 467.3 (1-1)-3 4.32 22 2 471 (l-l)-3 6.61 9 0 479 119 15 483 (l-3)-2 0.86 19 1 491 4 3.40 21 1 496 39 4 502 (1-1M1.3) 3.29 7 0 511.3 5 1.36 1 0 513 11 0 519 4 1 521.3 5-2 1.62 4 0 530 4 1.82 8 2 536 20 1 H 00 00 Percent Phragmodus Ozarkodina Phrag- Plectodina + Apelognathus Oulodus modus Phragmodus Polita Oregonia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 present present 0 0 present 0 0 present present 0 0 0 0 0 present 0 0 0 0 present 0 0 present Core Depth Percent Number Rock Insoluble of Plecto Type Materials Conodonts dina 542 6-5 1,93 9 0 554.7 2 0 564 36 3 574 5 0.8 42 1 583 6 1.72 135 8 596.2 5-6 1.97 13 0 606 5-6 2.42 0 616 0 627 2 5.07 0 637 4-6 3.18 3 0 647 4 10.42 26 6 658.7 (l-3)-2 4.66 104 2 666 4 5.32 2 0 678 6-3 10.70 25 1 686,6 6-5 8.21 47 3 695.4 H oo VO 5 4.07 54 0 Percent Phragmodus Ozarkodina Phrag- Plectodina + Apelognathus Oulodus modus Phragmodus Polita Oregonia 0 present 0 0 0 0 0 0 0 present 0 0 present 1 14.29 present 16 88.89 0 Byantodina 7 87.50 Amorphognathus abrupta 0 0 Belodina com- pressa 0 Table C Values for relative mechanical energy, relative depths, isopach and structural contour maps. 190 Core No. Coordinate X Y Relative Energy Values Relative Depth Value Case X Case II Structural Contour Topographic Elevation of Bottom of Time Strati- graphic Interval Total ness Thick- Isopach ft. meters in. meters CA-19 48 5 29.85 29.63 25.35 260 79.25 1848 46.94 CA-81 26 26 32.25 28.07 26.43 730 222.50 1828 46.43 CA-71 39 36 36.82 32,15 23.13 658 200.56 1864 47.35 CA-29 53 36 18.52 34.26 31.48 356 108.51 648 16.46 CA-43 17 69 34.00 29.70 26.00 310 94.49 1848 46.94 CA-84 32 65 34.24 28.87 25.76 445 135.64 924 23.47 CA-88 50 65 36.41 35.90 18,46 458 139,60 468 11.89 CA-100 83 66 34.85 37.07 23.23 163 49.68 1872 47.55 CA-27 25 91 33.05 32.60 26.95 48 14.63 1848 46.94 CA-61 42 86 34.35 34.83 25.65 192 58,52 588 14.94 CA-169 59 96 36.86 26.90 27.23 1848 46.94 CA-179 63 95 32.14 32.53 27.86 1848 46.94 CA-121 68 99 33.94 38.53 26,06 185 56.39 1856 47.14 CA-66 78 98 34.58 28.92 24.32 202 61.57 1824 46.33 CA-55 89 119 29.84 33.94 30.16 163 49.68 1776 45.11 DU-3 85 128 31.98 34.29 28.02 1800 47,72 CA-34 83 132 30.63 35.32 29.37 113 34,44 1776 45.11 152 114 186 17.18 42.82 42.82 1034 315,16 156 3.96 153 118 193 31.72 29.80 28.31 690 210.31 1584 40.23 162 121 197 38.82 25.91 21.18 892 271.88 1524 38.71 161 126 201 34.42 27.76 25.26 915 278,89 1484 37,69 166 120 203 34.84 25.39 23.59 771 235.00 1536 39.01 Core No, Coordinate X Y Relative Energy Values Relative Depth Value Case I Case II Structural Contour Topographic Elevation of Bottom of Time Strati- graphic Interval Total ness Thick- Isopach ft. meters in. meters 168 125 207 40.44 22.64 19.56 815 248.41 1560 39.62 170 117 210 36.25 24.71 23.75 875 266.70 1248 37.70 171 115 212 40.39 24.31 19.61 840 256.03 1020 25.91 199 144 199 30.00 33.74 30.00 698 212.75 1560 39.62 CA-35 172 202 29.97 27.94 26.11 312 95.10 1572 39.93 157 127 214 30.10 29.90 29.90 932 284.07 816 20.73 156 126 220 41.81 20.32 18.19 905 275.84 620 15.75 198 128 237 34.10 29.74 25.90 612 186.54 1560 39.62 196 127 262 33.60 31.45 29.77 507 154.53 1212 30.78 CA-57 159 264 31.90 34.49 28.10 471 143.56 1560 39.62 CA-37 174 251 33.15 32.62 26.85 151 46.02 1560 39.62 H VO M Explanation of Symbols for- Generalized Columnar Sections 193 KEY l - h - t S u b c l a s s l - l and 1 - 2 S u b c l a s s 1 - 3 I I C l a s s 2 ES C l a s s 3 EcH C l a s s 4 C l a s s 5 I I C l a s s 6 V e r t i c a l S c a l e lcm=6.09m(20ft) Icm* 19^ Figure 1 Generalized columnar section of core CA-19* 195 o o ■ O < T > j S ? * / - < ? < & <3 ° O o . o o ° o ° o * • ': d % ? £ % „ £ O p £ o S,0oo o ^°'<?.*q>.-.C| O "o$= ? « ' ' ? C2°; O: <P: e . ■ ° ° » * , * / 7 • ®. iC a f e ft* o o ° A ^ o ~ C > ° C > b 0 c » ° V S=>'X^ O/9.o \r 196 Figure 2 Generalized columnar section of core CA-81. 197 IIJZJZZL- ■ p : : ' ? s y 6 < Pi®® 198 Figure 3 Generalized columnar section of core CA-71. 199 0^°a£? < o ' ^Ci^^o<! Ipft® >vo <5 o-o 0, 9..^ ^ ^ OVo 9 m 3 i . t i = ? = p “r n r n r V ^ ' r n t j ± L ± d Figure h Generalized columnar core CA—29* section of* 201 2 0 2 Pirnre 5 Generalised, core CA—^3. columnar section of 203 a > o °Q o - o o • O . °o ^ Q n /v - ^ c?Sw y g h f r M oS?°5o 0 ^Cs a ? C'c-^O © c ?&<&'&*■ >s.°a*«*: r - n ^ * • • V v * / ? * ° - j C? O / — ^ o >>s ^ • ^ 4 : j . r ~ l y - ^ ra n , / l- 0 c s , i , .r i 204 Figure 6 Generalized columnar section of* core CA—84. 205 TZr T M issing E S 3 3 on r, f -r i M r c f f SZI 206 Figure 7 Generalized columnar section of core CA-88. 207 208 PigriT'e 8 Generalized columnar section of core CA—lOO, 209 ° Ob ’ a o~To - o ; Q C? o ^ ?7 Q > ° c ,_ , oa O . o ' J - . A <?•*> » O ° . f V . ° * C7 -” hlr t /0 ° 0 c3 o ° • s ^ w . t • ° < > O ° c °°y5~ o ° Q > o ^ 0 (7 < ? A ■ ® . . _ r v ^: a « o a r O O C2 'O\0 ° ° -:° O 0< c? ; : % 9 o # o O.iwQ •o ° o La CT IT'T, I ~fc^Z?73 < 1 U W .I 5 A ‘IT ^ rf i T z w z m f T T ~ T i r i — r i Figoire 9- Generalized columnar section of core CA—27. 211 « • & r - > * ° A c ° °o <£>?-* C/o r > o o <3 < 2 , ° c ? o - ■ C? O « > -X r~) o' o < W < x . 0^ ^ °< ? ^ Oo. i°°n ’ a £ ? o ” < 0 < Z D &> £? o o o ' O 0 0 ? O e=! . O. : s , ° C3 * ° - 0 " , C ? o (Q:o • „ O O o £> 0^7 V<9i??- XVy® o 0 < 2(O F b c ? .g q J v ’ a 0 >*v C O - ^ - © • C. MQ^-q j i' L*-(?±: 3 = W S o T E i K ^ n o » o P • 2 1 2 Figure 10. Generalized columnar section of core CA—6l. 213 o . C ? 0 V >VoO * cl < *e=‘ a • - ^ ' L o D or J , ; . & c>. 'c&l&a ^ o U< :C 0'*ca*« — - > O ^ 3 ° < 3 0 O'p.'9- ® S.fi p ‘ ^ e c=> ’ a Q °a > o <o o V -C ? C=> cs > * o ^ & A ° 0 • C> ^ o / O ; o : o . p ^ < > o > ^ r &OcfOS>: oi l g >» r > < [ : o ' l p " r > - ^■■0:0 p;" m m : i ti'ti M issing 214 Plg'ux'e 11* Generalized columnar section of core CA—I69. 215 So < 3 G > V* oCZ o C D \ s & a M $ o 1 . 1 r‘rJ w ? 111111T ,' f m "■ 111 r~r~T i | i ' i ' I 216 Figure 12. Generalized, columnar section of core CA-179. 217 Q CN^O \ O ' . C J 6 , 0 O I . Ttrn ■ cz^ E ^ . ojs EZCZI. nz czi; n ~ ~r 3=3=1 1 ~7IZI.T ■ > —» J —^ t a\ J o o O ^fvv»*C^.* T E~X~E r n 7®V' : " ’ • y ' » 1 ^ - 3 . ^ • e o V t I ~I I r t n w i :a o r.rznr. t i, -"jo " i ' y y ^ * * fT T ? 218 Pi grume 13* Generalized columnar section of cone CA—121* 219 O'ou „ « • = > .vo ty,p. f g ^ b & g s ? r * ° A ^<c ^0V O / —> ° c s r < 0 T ) ° ^ k V? * > o o ? . i • « ? O aZ ' o^* < £ > & g g £ y & , H CZi^ JZ E o itin 9-/m- r r m « - £ > ^2. z r x z i r j i AiTlm-Za^0 & '•nyan>t^. p&J ^ w? .n> rsV. r , - 0 . V t 2 2 0 Figime 14 Generalized columnar section of* cone CA—66* 221 2 2 2 Figure 15. Generalized columnar section of core CA-55 223 > c > p ! p i . !.! i , i Fig'll re l6 # Generalized co lumnar sec tion of core DU—3* 225 J r 1 . 1"ZE 226 Figure 17* Generalized columnar section of core CA—3^* 227 c O rc> O '/ , k ^ ; d ° V» £ ? <0 p • _ . • • ^OQ < ? Vj<p- ^ O . 0 B ( —5 >'P?€>: *zO > Ct> «1b * ■ ' - o ■ ; < s a . ■ C ? o. . °<=-,PO / t> O # V .: Ay_ ;o>oo '.c ?C/£^- v?0■ > jv ’ . 0 P/ 7 .0 * 0 0 . Q o Q i c 3 ; ;<? c < *< m c ^ > 2 & ' j 2^L ,o'»? - — a . .»■ I ITT 228 Figure 18. Generalized columnar section of core 152. 229 I " ' ' I ‘1 i 1 r* i ESPS 230 Pi/nnre 19* Generalized columnar section of • e > cone 231 • ■0VO'rt'/Q #O' ' . ^ V o ^ o ^ ■ • * ° _ r~> . °- o ‘ ■^ovo“? o^.< >A, •O0..» ir«Ar?A ° O a i i . . . . : . i T^T e z z W ? i . i i , mi 232 Figure 20. Generalized columnar section of core 162. 233 I l l I \c?-£ P ^ O O , 0 C*c% ?y_<Q* &Sa £ l _ l L -r-i— r~-T I l i p " | ' ~ j I ‘ I T » i 1 i r B 234 Flgnine 21. Generalized columnar section, of cone l6l. 235 ~t 1 i 1 i I=r ? .&oPo°<£> oC= > Q q o * tfo o o T i r *’ £ ii i 7 p ' o^c.l X' J S~L° p 5 > f ^ r ? ^ 11 < ? 9 <^» 12 i I r 236 Figure 22* Generalized columnar section of core 166. 237 0 c? x > . \ * <D O >o o o .Vo1 c dC* o CP u - a 7"f y i r I S I w ' ' I 238 Figure 23* Generalized columnar’ section of cone l68* 239 □ T . H Z I I .."I. 1 1 3.1 X-4-l xz 1 I 1 I JZZZL 240 Figure 2b* Generalized, columnar section of core 170. 2bl .I. 1,1.1 M 3 i — i — n i i 11 242 Figure 2 5 Generalised columnar* section of core 171* 2^3 i :r i : Figure 26. Generalized columnar section of core 199* 245 10 - p * 0\ m i I01 0 01 ©( 3 a--q Figure 27 Generalized coluinnar section of cone CA—35* 0^3 24 / i t i — r rs ' w ' . ' w ' u Q ° " P ° ° 1 n ' O ( ■ o lo-?? C> * < o CS ° ° - /~N o •oa* r i i 248 Figure 28, Generalized columnar section of cone 157* 2^9 i i 250 Figure 29* Generalized columnar' section of core 15 6 * 2 51 E M 5p5 ?n jyo3s<?o©\. i r ^ - r it r n t i i r 252 Figure 30* Generalized, columnar section of cone 198, 2 53 T 1 T 1 I r x 3 r o “ A ° .Q C I I I T V °0°Oi o j m : Figoii'e 31 Generalized core 196* columnar section of 233 T~~ T ~L~ _ L 25 6 L&z • IZ-VQ 9-100 JO UOTJO0S JL’UimiOO p9ZTX^9U0f) * ZC 9Jn2lJ[ a 253 Figrm e Generalized columnar section of cone CA—37# 2 59 260

Asset Metadata

Creator Borella, Peter Edward (author)

Core Title Petrologic and stratigraphic relationships among middle Ordovician limestones from central Kentucky to central Tennessee

Contributor Digitized by ProQuest (provenance)

Degree Doctor of Philosophy

Degree Program Geological Sciences

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag OAI-PMH Harvest,Sedimentary Geology

Language English

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c29-341607

Unique identifier UC11218818

Identifier DP28535.pdf (filename),usctheses-c29-341607 (legacy record id)

Legacy Identifier DP28535.pdf

Dmrecord 341607

Document Type Dissertation

Rights Borella, Peter Edward

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA