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Early Diagenesis In Southern California Continental Borderland Sediments

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Early Diagenesis In Southern California Continental Borderland Sediments

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Content INFORMATION TO USERS This material was produoad from a microfilm copy of the original document. White tha moat advanead technological maant to photograph and raproduoa this documant have baan used, tha quality h haavily dapandant upon tha quality of tha original submitted. Tha following axpianation of tachniquat is providad to halp you undarstand markings or patterns which may appaac on this reproduction. 1. Tha sign or ''target” for pages apparently lacking from tha documant photographed is "Missing PagsUI". if it was possible to obtain tha missing page(s) or suction, they are spliced into tha film along with adjacent pages. This may hava necessitated cutting thru an imago and duplicating adjacent pagas to insure you complete continuity. 2. Whan an image on tha film is obliterated with a largo round black mark, it is an indication that tha photographer suspected that the copy may hava moved during exposure and thus causa a blurred image. You will find a good image of tha paga in tha adjacent frame. 3. Whan a map, drawing or chart, etc., was part of tha material being photographed the photographer followed a definite method in "sectioning" tha material. It is customary to begin photoing at tha upper left hand comer of a large shwet and to continue photoing from toft to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below tha first row and continuing on until complete. 4. The majority of users indicate that tha textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pegas you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Z M b fto te Ann A rter, MtcMgM 461 O S BOOTH, Janes Storms, 1945- EARLY DIAGENESIS IN SOUIHERN CALIFORNIA CONTINENTAL BORDERLAND SEDIMENTS. University of Southern California, Ph.D., 1$74 Geology University Microfilms, A X ER O X Com pany, Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVEO. EARLY DIAGENESIS IN SOUTHERN CALIFORNIA CONTINENTAL BORDERLAND SEDIMENTS by Jam es Storm s Booth A D i s s e r t a t i o n P re s e n te d t o th e FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In P a r t i a l F u lf illm e n t o f th e R eq u irem en ts f o r th e D egree DOCTOR OF PHILOSOPHY (G e o lo g ic a l S c ie n c e s ) J a n u a ry 1974 UNIVERSITY O F SO U T H E R N CA LIFORNIA THR ORADUATK SCHOOL UNIVERSITY PARK LOR AMOKLU, CALIFORNIA * 0 0 0 7 This dissertation, written by under the direction of h .L D is s e r ta tio n Com mittee, and approved by all its members, has been presented to and accepted by The Graduate School, in partial fulfillment of requirements of the degree of D O C T O R OF P H I L O S O P H Y _______ ( / ........... Date. N X O M M H TE, CONTENTS Page ILLUSTRATIONS .................................................................................................................... v ABSTRACT ................................................................................................................ .............. ix INTRODUCTION *............................................................................................ . ..................... 1 G e n e ra l s ta te m e n t ...................................................................................................... 1 Approach to th e p r o b le m ........................................................................................ 2 P re v io u s work ..................................................................................................... 2 S tudy a r e a ............................................................................................................ 12 Acknowledgments .......................................................................................................... 15 M ETHODS .................................................................................................................................. 16 S h ip b o ard p ro c e d u re s .............................................................................................. 16 L a b o rato ry p ro c e d u re s ............................................................................................ 19 P o re w a te r ..................................................................................................... 19 B ulk c h e m i s t r y ...................................................................................................... 21 Amorphous m a te r ia l ............................................................................................ 23 F re e i r o n ................................................................................................................. 25 M ineralogy ............................................................................................................... 25 T e x tu ra l a n a ly s is .......................... *................................................................. 28 Smear m ounts .......................................................................................................... 29 PORE W ATER CHEMISTRY ......................................................................................... 30 M ajor c a tio n s ............................................................................................................... 30 S i l i c a ..................................................................................................................... U6 11 Page C h lo r in ity ...................................................................................................................... ^6 pH .................................................................... 61 D i s c u s s i o n ...................................................................................................................... 6 l BUUC CHEMISTRY .................................................................................................................. 71 O xides ............................................................................*................................................. 71 Amorphous s i l i c a ........................................................................................................ 87 Amorphous a lu m ln o s ilic a te s ................................................................................ 90 S t r u c t u r a l I r o n - f r e e ir o n .............................................................................. 90 D is c u ss io n ...................................................................................................................... 97 MINERALOGY ..................................... .................................................................................... 100 N o n -clay m in e ra ls ...................................................................................................... 100 C lay m in e ra ls ............................................................................. *............................... 100 D is c u ss io n .................................................................................... *............................... 101 TEXTURAL ANALYSIS .......................................................................................................... 117 GENERAL DISCUSSION................................................................................ . ..................... 132 C hem ical r e l a t io n s h i p s .......................................................................................... 132 Mg+^ - M gO s y s t e m ............................................................................................... 133 K + - KgO s y s t e m ................................................................................................... 150 Na+ - NagO s y s t e m .............................................................................. . .............. 152 3102 (M ) ' 8 i °2< «orp h ) - U 2°3- S i°2 8 y ,t “ .............................. 153 D ia g e n e s is i n c la y s .......................................................................................... 155 P h y s ic a l r e l a t io n s h i p s ............................................................................... . . . . 162 i l l Page SUMMARY AND CONCLUSIONS ........................................ l6U REFERENCES ........................................................................................................................... 1^9 iv 1 2 3 U 5 6 7 e 9 10 1 1 12 13 ik 15 16 17 18 19 20 2 1 22 13 31 33 35 37 39 Ul 1*3 1 * 7 k9 51 53 55 57 59 73 75 77 79 81 83 85 ILLUSTRATIONS S t a t i o n l o c a t i o n s and g e n e r a l a r e a o f s t u d / M ajor c a tio n tr e n d s - c o re AHF 16991 ............... M ajor c a t i o n tr e n d s - c o re AHF 1 6 9 9 k ............... M ajor c a t i o n tr e n d s - c o re AHF 16996 ............... M ajor c a tio n tr e n d s - c o re AHF 16997 . . . . . . . M ajor c a tio n tre n d B - c o re AHF 17807 ................ M ajor c a tio n tr e n d s - c o re AHF 17611 ................ M ajor c a tio n tr e n d s - c o re AHF 181*36 ................ S i l i c a , c h l o r i n i t y , and pH t r e n d s , 16991 S i l i c a , c h l o r i n i t y , an d pH t r e n d s , 1699** S i l i c a , c h l o r i n i t y , and pH t r e n d s , 16996 . . . S i l i c a , c h l o r i n i t y , and pH t r e n d s , 16997 S i l i c a , c h l o r i n i t y , and pH t r e n d s , 17801* . . . S i l i c a , c h l o r i n i t y , and pH t r e n d s , 17811 . . . S i l i c a , c h l o r i n i t y , and pH t r e n d s , I 8U36 . . . T ren d s i n o x id e s f c o re AHF 16991 ......................... T ren d s in o x id e s , c o re AHF l6 9 9 * * ............... T ren d s i n o x id e s , c o re AHF 16996 ............... T ren d s i n o x id e s , c o re AHF 16997 ......................... T ren d s i n o x id e s , c o re AHF 17801* ......................... T ren d s i n o x id e s , c o re AHF 1 7 8 1 1 ....................... T ren d s i n o x id e s , c o r e AHF 181*36 .................... v F ig u re s Page8 23 Amorphous s i l i c a abundance............................................................. 68 2U Amorphous a lu m ln o s illc a te ............................................................... 91 25 S t r u c t u r a l I ro n .................................................................................... 93 26 " F re e -Iro n " .............................................................................................. 95 27 R e la tiv e abundance In c la y m in e r a ls . Core AHF 16991 ..................................................................................... 102 28 R e la tiv e abundance In c la y m in e r a ls , Core AHF 16991* ..................................................................................... 10U 29 R e la tiv e abundance i n c la y m in e r a ls , Core AHF 1 6 9 9 6 .................. 106 30 R e la tiv e abundance i n c la y m in e r a ls . Core AHF 16997 ................................................................................... 108 31 R e la tiv e abundance i n c la y m in e r a ls , Core AHF 1780U ................................................................................... 110 32 R e la tiv e abundance i n c la y m in e r a ls . Core AHF 17811 ................................................................................... 112 33 R e la tiv e abundance In c la y m in e r a ls , Core 101*36 ........................................................................................... Ill* 3U Mean g r a in s iz e and s o r t i n g , c o re AHF 16991 ................ 118 35 Mean g r a in s iz e and s o r t i n g , c o re AHF l699l* ........... 120 36 Mean g r a in s i z e and s o r t i n g , c o re AHF 16996 ................ 122 37 Mean g r a in s i z e and s o r t i n g , c o re AHF 16997 * • ........... 121* 38 Mean g r a in s iz e and s o r t i n g , c o re AHF I 780U ................ 126 39 Mean g r a in s iz e and s o r t i n g , c o re AHF 1 7 8 1 1 ................ 128 1*0 Mean g r a in s iz e and s o r t i n g , c o re AHF 101*36................ 130 1* 1 C a lc u la te d i d e a l ran g e in o x id e s , c o re AHF 16991 . . 13I * 1 * 2 C a lc u la te d i d e a l ra n g e i n o x id e s , c o re AHF 16991* . . 136 v i F ig u re s * *3 C a lc u la te d I d e a l ra n g e i n o x i d e s , c o re P ag es AHF 16996 . . . 138 U i+ C a lc u la te d I d e a l ra n g e i n o x id e s , c o re AHF 1699T . . . 11*0 1 * 5 C a lc u la te d I d e a l ra n g e i n o x id e s , c o re AHF 17001* . . . ll*2 U6 C a lc u la te d i d e a l ra n g e i n o x id e s , c o re AHF 17811 . . . lUI* 1*7 C a lc u la te d i d e a l ra n g e i n o x i d e s , c o re AHF 101*36 . . . ll*6 v i i TABLES Page T a b le I ................................................................................................................................. 3 T ab le I I ............................................................ 5 T ab le I I I ............................................................................................................................. IT T ab le IV ............................................................................................................................... 6U T ab le V ................................................................................................................................. 160 v l i i ABSTRACT R e a c tio n s b etw een p o re w a te r c o n s titu e n ts and s o l i d m a te r ia l w ere exam ined w ith r e g a rd t o ty p e and q u a n t i t a t i v e im p o rtan ce i n sed im en ts o f th e S o u th e rn C a lif o r n ia C o n tin e n ta l B o rd e rla n d . T h is a r e a i s c h a r a c te r iz e d by i t s h ig h an d ch an g eab le r a t e s o f d e p o s itio n as com pared t o deep s e a c o n d itio n s , s i g n i f i c a n t o rg a n ic c o n te n t, and a v a r i e t y o f p h y s io g ra p h ic e n v iro n m e n ts w hich p ro v id e d th e s i t e s f o r th e study* The p roblem was a p p ro ach ed from fo u r d i r e c t i o n s : ( l ) p o re w a te r c h e m is try , (2 ) b u lk c h e m is try , (3 ) q u a n t i t a t i v e m in e ra lo g y , and (U) t e x t u r a l d e te r m in a tio n s . T hese a n a ly s e s w ere p erfo rm e d on sev en p is to n c o re s from th e f lo o r s o f San N ic o la s , S a n ta C ruz, and S a n ta C a ta lin a B a s in s. The e r r a t i c n a tu re o f th e p o re w a te r d a ta p r e c lu d e s d e f i n i t i v e c o n c lu s io n s . However, c e r t a i n lik e lih o o d s m a n ife s t th em selv es +2 th ro u g h c o n ju n c tiv e u se o f th e s e v e r a l l i n e s o f e v id e n c e . The M g - MgO sy stem was found t o be a c t i v e i n exchange s i t e s . T h is was s u g g e s te d by an a p p a re n t d e c re a s e i n i n t e r s t i t i a l M g c o n c e n tra t i o n w ith in c r e a s in g d e p th below th e se d lm e n t-w a te r i n t e r f a c e , c o u p led w ith v is * v ia r e l a t i o n s h i p w ith p r o f i l e s from t h e b u lk c h e m ic al d a ta . A la c k o f n e g a tiv e e v id e n c e frcm th e c la y m in e ra l o g y , and coaqpatable e v id e n c e from exchange s i t e s d a ta s u p p o rte d t h i s . The It* - K^O and Ma+ - BagO s y s te m s ' a c t i v i t y w ere l e s s o b v io u s, a lth o u g h sim u lta n e o u s d i s s o l u t i o n o f K -fe ld s p a r and en trap m en t i n ix exchange a l t e s may h e o c c u rin g i n th e fo rm er system * , and sim p le up ta k e on c la y a may h e h ap p en in g i n th e l a t t e r . The B iO g ^ ^ j - “ Amorphous A l-s i l l c a te s eyatem was c h a r a c te r iz e d by s i°2(A q.) e n ric lw ie n t» due e i t h e r t o r e l e a s e "by c la y o r d is s o l u t i o n o f s l l l c i o u s h io g e n ic re m a in s, and a dependence on p h y s ic a l f a c t o r s . S p e c i f i c a l l y , in c r e a s in g am orphous alu m in o - s i l l c a t e p e rc e n ta g e s w ith d e p th w ere Judged t o be c o n t r o ll e d by i n f l u x o f a g r e a t e r amount o f th e te r r ig e n o u s m a te r ia l d u rin g th e l a s t low s ta n d o f th e a e a ( c a . 1 2 ,0 0 0 t o 15 ,0 0 0 y e a r s B .P .) . The b io g e n ic com ponent was c o n c o m ita n tly d i l u t e d by e l a s t i c s o r p o s s ib ly d e c re a s e d a t t h a t tim e . C a tio n and s i l i c a a c t i v i t y was m a n ife s t to th e h ig h e s t d e g ree i n th e u p p e r m e te r o f s e d im e n t. The c a tio n s by th e m se lv e s showed a d ia g e n e tic a s s o c i a t i o n w ith th e exchange s i t e s o n ly . No e v id e n c e was found t o s u g g e s t t h a t th e c la y m in e ra ls w ere b e in g a l t e r e d o r t h a t c la y m in e ra ls w ere b e in g form ed a u t h i g e n i c a l l y . F i n a l l y , m echanisms w ere so u g h t w hich co u ld e x p la in th e f lu c t u a t i o n s o b se rv e d i n th e v a rio u s p o re w a te r s p e c ie s c o n c e n tr a tio n s . I t was c o n c lu d e d t h a t g r a in s i z e , and t h e r e f o r e p o s s ib ly s u rf a c e a r e a , e x e r te d a s tr o n g in f lu e n c e on p o re w a te r c o m p o sitio n w ith membrane e f f e c t s , s p ik in g by a n c ie n t s e a w a te r r e s i d u e s , and o rg a n ic com plexes p la y in g a s u b o rd in a n t r o le in th e en v iro n m e n ts exam ined in t h i s s tu d y . B ecause o f a l l th e s e c a u se s o f p e r tu b a tio n th e sed im en ts o f th e c o n tin e n ta l m arg in a r e a s tu d ie d a r e n o t b e lie v e d t o be i n a s t a t e o f ch em ica l e q u ilib riu m . INTRODUCTION G en eral S ta te m e n t The phenomenon o f e a r l y d ia g e n e s is , a lth o u g h th e s u b je c t o f much s p e c u la tio n and t h e o r i z a t i o n ( s e e , f o r exam p le, S i l l e n 1961; M ackenzie and G a r r e ls , 1 966; S le v e r 1 968; o r B ro e c k e r, 1 9 T 1 ), has n o t r e c e iv e d in te n s iv e f i e l d I n v e s t i g a t i o n . I t commonly i s b e lie v e d t h a t c h em ica l changes o c c u r in th e in o rg a n ic p h a se s b e f o re o r s h o r tly a f t e r d e p o s itio n , a b e l i e f c e n te r e d aro u n d th e co n cep t t h a t c la y m in e ra ls w i l l r e a c t r a p id ly w ith io n ic s p e c ie s in se a w a te r d u rin g i n i t i a l e x p o s u re . F u r th e r , i f th e o cean s a re a t o r n e a r a s t a t e o f c h e m ic al e q u ilib r iu m , th e r e m ust b e a b a la n c e betw een th e d is s o lv e d lo a d e n te r in g v i a stre a m s and th e rem oval o f th e s e same io n s from th e o c e a n . In o r d e r t o gage th e v a l i d i t y o f t h i s s y llo g is m i t m ust b e d e te rm in e d i f c la y m in e ra ls a r e a l t e r e d , e i t h e r s t r u c t u r a l l y o r w ith r e g a rd t o th e c o m p o sitio n o f t h e i r exchange s i t e s , t o accom m odate th e d is s o lv e d lo a d . T hat i s , w hat i a th e e x te n t o f e a r ly d ia g e n e s is o f c la y s and does i t p ro v id e an e f f e c t i v e mechanism f o r th e rem oval o f th e v a rio u s io n ic s p e c ie s ? I t was th e prim e o b je c t i v e o f t h i s r e s e a r c h t o answ er th e s e q u e s tio n s . The q u e s tio n o f th e ch em ic al e q u ilib riu m o f th e oceans i s b a s ic t o any fo rm u la tio n o f th e ch em ical h i s t o r y and o r ig i n o f th e ocean . I n t h i s r e g a r d , th e stu d y p ro v id e s an i n d i c a t i o n o f th e s i t e w here 1 2 e q u ilib riu m i s a c h ie v e d . I e i t r a p i d and a p p ro ach ed in th e con t i n e n t a l m arg in s o r i s i t slow and comes t o n e a r b a la n c e i n th e deep ocean? In a d d itio n t o t h i s b a s ic g o a l, w hich i s c h i e f l y a ch em ical o n e , th e r e l a t i o n s h i p betw een th e ch em ical and th e p h y s ic a l sy stem s w ould b e i n v e s t i g a t e d . A pproach t o th e Problem B ecause so few s tu d ie s have com bined two o r m ore s e p a r a te l i n e s o f e v id e n c e , i t was d e c id e d t h a t a com prehensive ap p ro ach was n e c e s s a ry t o h e lp f i l l th e v o id . T h u s, g a in in g a c c e s s t o th e p ro b lem s o f e a r ly d ia g e n e s is was acco m p lish ed b y u t i l i z i n g f o u r avenues o f ap p ro ach : ( l ) p o re w a te r c h e m is try , (2 ) b u lk c h e m is try , (3 ) c la y m in e ra lo g y , and (U) t e x t u r a l a n a ly s is * The c o n ju n c tiv e u se o f th e s e f o u r "av en u es" was Judged t o be a p r a c t i c a l means to a c h ie v e a firm b a s e upon w hich to make i n t e r p r e t a t i o n s . P re v io u s Work C o n sid e rin g w o rld stre a m r u n o f f , G a rre ls and M ackenzie (1971) c a lc u la te d th e tim e f o r r i v e r f lu x e s to a t t a i n o c e a n ic v a lu e s f o r s e v e r a l io n s . T hese a r e l i s t e d i n T ab le I i n o rd e r o f in c r e a s in g le n g th s o f tim e . A g e n e r a l p a t t e r n o f th e r a t e o f rem oval i s t h e r e f o r e i n d ic a te d . P re v io u s work has b een done on many o f th e s e s p e c i e s , th e m ost o b v io u s o f w hich i s Ca w hich has a c l e a r p a th o f re m o v a l, b e in g " lo c k e d -u p " 3 TABLE I Time n eed ed f o r v a r io u s s p e c ie s t o re a c h o c e a n ic v a lu e s Time n eed ed t o re g c h S p e c ie s O cean ic v a lu e s (x 10 SiOg 0.02 hco3 0 .1 0 Ca+2 1.2U K+ 8 .0 0 M g+2 1 5 .U0 Ha+ 1 0 8 .0 0 i n c a rb o n a te p h a s e s . The Anion HCO^_ v a s s tu d ie d by M ackenzie and G a r r e lt ( 1966) who p o s tu la te d t h a t In a d d itio n t o a id in g In th e fo rm a tio n o f CaCO^ i t a ls o may i n t e r a c t In th e fo llo w in g m anner: Amorphous A l - s i l i e a t e + s ^°2 + H C °3 + c a tio n s * c a tio n A l - s i l i c a t e + CO^ + HgO T h is " r e v e r s e w e a th e rin g " r e a c t i o n , i n w hich CO^ i s r e le a s e d r a t h e r th a n consum ed, c a ta ly z e d a su rg e i n d ia g e n e tlc s tu d i e s b e c a u se i t o f f e r e d an e x p la n a tio n f o r a p o s s ib le u p ta k e mechanism f o r th e m ajo r c a t i o n s , HCO^ , and S iO g ^ ^ j a s th e y e n te re d s e a w a te r. A lso , i t o f f e r e d a s o lu tio n t o th e dilem m a o f c o n tin u e d CO^ d e p le tio n from th e atm o sp h ere w ith h e r e to f o r e no known way f o r i t t o be re c h a rg e d . H ow ever, th e r e a c tio n i s h y p o th e tic a l and i t rem ain ed f o r a h o s t o f i n v e s t i g a t o r s to a u d it. I n t e r s t i t i a l w a te rs have b een a n a ly z e d by s e v e r a l w orkers i n o r d e r t o p ro v id e f i e l d e v id e n c e w hich c o u ld b e a r on t h i s th e o ry o f d la g e n e s is . A summary o f some o f t h e i r f in d in g s i s p r e s e n te d in T ab le I I w ith em phasis on th e m ajo r c a tio n s in s e a w a te r p lu s c h lo r i n i t y . A lthough many o f th e a b s o lu te v a lu e s m easured b y th e above w o rk ers w ere t a i n t e d b y f a i l i n g t o sq u eeze o u t t h e i r p o re w a te rs a t iti s i t u te m p e ra tu re s (M a n g e lsd o rf, e t a l . , 1969* B is c h o f f , e t a l . , 1970) th e r e l a t i v e change I n d ic a te d i s v a lid . A p e r u s a l o f T ab le I I r e v e a ls t h a t i n no c a se does c o n c e n tr a tio n o f a g iv e n io n alw ays change i n th e same d i r e c t i o n . T h is la c k o f c o n s is te n c y u n d e rs c o re s many o f th e pro b lem s in d e a lin g w ith n a tu r a l s y ste m s. N o n e th e le s s , th e p re v io u s f in d in g s do r e v e a l t h a t each 5 TABLE I I Changes in th a C o n cen tratio n a n d /o r D ifferen c es v i th Bottom W ater o f ttie M ajor C atio n s as R eported by P rev io u s In v e s tig a to r s OEKERAL A L F T H 0 R 3 *2 ♦2 l a Cl A ll e t a l . 1972 B a ffin Bay d ec re a se c o n s ta n t c o n s ta n t c o n s ta n t In c re a se B isc h o ff A Ku 19T0 M ld-A tl. Ridge c o n s ta n t In c re a se d ec rea se c o n s ta n t B isc h o ff A Ku 19T1 E ast I . - A t l . c o n sta n t in c re a s e d e p le tio n e c o n s ta n t B isc h o ff a Saylea 1972 Qalapagoe I s l . c o n s ta n t c o n sta n t co n sta n t c o n s ta n t B rooks, P re s le y a Kaplan 1968 So. C al. B orderland d ec re a se in c re a s e d ecrease Drever 1971 Bandares Bay* Hex. co n st an t c o n a ta n t Priedman e t a l . 1968 O ff Ion g - Ia la n d in c re a s e in c re a s e c o n s ta n t rr ie f e a n a Oavish 1970 Hear sh o n Hew York in c re a s e d ecrease d ec rea se d ec rea se c o n s ta n t Bulbs r t a Oiven ( in p r e p .) G ulf o f Maine d ec rea se in c re a s e d ecrease c o n s ta n t c o n sta n t K angelsdorf 1969 B ussards Bay* Haas In c re a se Murray 1973 S t. Barb. B asia-S o . C a lif . B orderlan d ec rea se In c re a se decrease c o n sta n t K iaaenbaia • t i i - 19T2 Saanich I n l e t Vancouver I s l . d ec re a se In c rea se c o n sta n t o 2 6 m d ec rea se B b o lk o v lts 1973 S t. Bart*. B asin d ec rea se In c re a se d ec rea se c o n s ta n t c o n sta n t S la v e r a l . 1965 S e v eral c o n sta n t in c re a s e d ecrease v a r ie s v a r ie s 6 elem en t s tu d ie d d is p la y s a p en ch an t f o r a p a r t i c u l a r tr e n d . a Ca te n d s to d e c re a s e w ith d e p th in to th e s e d im e n t, e s p e c ia lly In an o x ic en vironm ents* Many w o rk ers ( e .g . S h o lk o v itz , 1972; P r e s le y , e t a l . . 1968; and H u lb e rt and G iven, In p r e p a r a tio n ) have p o s tu la te d t h a t t h i s d e c re a s e I s m irro re d by a p r e c i p i t a t i o n o f CaCO^. T h is c o n ce p t i s co n g ru e n t w ith th e t h e o r e t i c a l m odel o f G ardner (1 9 7 3 ). And, a s s t a t e d p r e v io u s ly , G a rre la and M ackenzie (1966) have o f f e r e d a so u rc e f o r p a r t o f th e su p p ly o f b ic a rb o n a te io n s to combine w ith a l l o f th e Ca+^. I - | M urray (1973) b e lie v e s t h a t in re d u c in g en v iro n m en ts Ca may be p u lle d in to o rg a n ic com plexes such as a d ip o c e r e s . These com plexes have been shown to be more s ta b l e th a n CaCO^ u n d er th e s e c o n d itio n s (B e rn e r, 1 9 7 0 ). Such o rg a n ic com pounds, how ever, a r e o n ly a tempo r a r y Ca++ r e s e r v o i r and u ltim a te ly a c a lc iu m c a rb o n a te w i l l p o s s ib ly form . The q u e s tio n o f th e c alciu m io n , th e n , seems to be la r g e ly r e s o lv e d . A re p lac e m en t o f Ca+^ by K + in c la y s was n o te d by R u s s e ll (1970) w orking in th e Rio Ameca, M exico and I t s m arin e r e c e p ta b le , B anderas Bay. lie was shown t h a t p e rh a p s a s much as 47% o f th e w orldw ide K + s u p p ly may be ta k e n up In t h i s m anner. Of s ig n if ic a n c e to t h i s s tu d y , how ever, i s n o t o n ly w here th e p o ta ssiu m i s g o in g , b u t w here i t Is coming from . R u s s e ll 's s tu d y In d ic a te d th a t t h i s u p ta k e o c c u rre d a s a h a lm y ro lic r e a c t i o n , y e t most r e s e a r c h e r s have d is c o v e re d an e n ric h m e n t o f K + w ith d e p th — in d ic a tin g t h a t t h i s io n I s b e in g m o b iliz e d I n th e sed im en t and some ty p e o f d ia g e n e tic r e a c tio n i s ta k in g p la c e . G u lf C oast w e lls y ie ld In fo rm a tio n t h a t s u g g e s ts K + 7 may b e coming from d e t r i t a l m icas below 1000 m (P e rry and H over, 1 9 7 0 ), b u t t h i s d e p th I s way beyond th e realm s o f th e e a r l y d ia g e n e tic l e v e l : th e u p p e r few m e te rs o f s e d im e n t. Many w o rk ers ( e .g . S ie v e r , e t a l . , 1969, M a n g e lsd o rf, e t a l . , 19^9) b e lie v e d t h a t K -fe ld s p a r d i s s o l u t i o n c o u ld p ro v id e th e n e c e s s a ry p o ta ssiu m io n s f o r e n r ic h ment* I l l i t e and m o n tm o rillo n lte a r e a ls o c a p a b le o f p ro v id in g K* a lth o u g h th e y a r e b o th e q u a lly c a p a b le o f rem oving i t (B is c h o ff and Ku, 1 9 7 0 ). The p o s s ib le i n t e r r e l a t i o n s h i p b etw een K*, i l l i t e and m o n tm o rillo n lte was d e b a te d by G rim , e t a l . (1 9 ^ 9 ), an d W eaver (1 9 5 8 ). The in c o n c lu s iv e n a tu r e o f t h e i r argum ents t r i g g e r e d s p e c u la tio n s by su c c e e d in g a u th o r s . M agnesium shovB a m ore c o n s is te n t tr e n d th a n any o th e r c a tio n . T hat tr e n d i s t o d e c re a s e w ith d e p th I n to th e s e d im e n t. B ecause o f i t s c o n s is te n c y i t h a s r e c e iv e d a d e t a i l e d e x a m in a tio n by s e v e r a l i n v e s t i g a t o r s . I n h i s s tu d y o f th e F lo Ameca, R u s s e ll (1970) con c lu d e d t h a t c la y s d id n o t exchange f o r Mg** t o any a p p r e c ia b le de g r e e . In a com plem entary s tu d y i n B anderas B ay, M exico, D rever (1971) +2 p o s tu la te d t h a t M g may b e rem oved from th e i n t e r s t i t i a l s o lu tio n +2 i n a n a e r o b i c b a s i n s by r e p l a c e m e n t o f Fe i n s h e e t s i l l c a t e B , t h e +2 i r o n r e a c tin g w ith H^S and th e M g r e p la c in g i t i n th e c la y m in e ra ls . In a d d itio n to t h i s h y p o th e s is D rev er ( in p r e s s ) p r e s e n te d p e rh a p s th e b e s t d is c u s s io n o f p o s s ib le s in k s f o r m agnesium t o d a te . U t i l i z in g p o re w a te r , b u lk c h e m is try , exchange c a p a c i t i e s and c la y m in er alo g y d a ta i n h i s a n a ly s e s , he su rm ized t h a t th e Mg-Fe exchange in c la y m in e ra ls may b e th e m ost im p o rta n t m echanism f o r re m o v a l, p a r t i c u l a r l y i n re d u c in g e n v iro n m e n ts, and t h a t c a rb o n a te fo rm a tio n , 8 sim p le Io n ex ch an g e, g la u c o n ite fo rm a tio n , and b u r i a l o f i n t e r s t i t i a l w a te r a ls o c o n tr ib u te t o u p ta k e . S h o lk o v itz (1972) b e lie v e d t h a t ir o n I s n o t re p la c e d i n th e c l a y s , b u t t h a t th e r e d u c tio n o f " f r e e " ir o n o x id e s w hich can s h e a th th e c la y s c o u ld r e s u l t In a s tr i p p i n g phenomenon w hich ex p o ses empty exchange s i t e s . These s i t e s +2 may th e n b e f i l l e d w ith M g • S e p i o l i t e and c h l o r i t e fo rm in g in s i t u may a ls o be s i n k s , as was p o in te d o u t by B is c h o ff and S a y le s (1972) and B is c h o ff and Ku (1970) r e s p e c t i v e l y . W ith t h i s p ro fu s io n o f c h o ic e s , m ost o f w hich a r e c o n j e c t u r a l , i t i s d i f f i c u l t to id e n t i f y th e p r i n c i p a l r e a c tio n s and e s tim a te t h e i r q u a n t i t a t i v e im p a c t. In f a c t , o rg a n ic com plexes may even b e In v o lv e d (H u rray , 1 9 7 3 ). D rever ( in p r e s s ) s p e c u la te s t h a t m an 's a g r a r ia n a c t i v i t i e s may be p ro v id in g an anom alously h ig h d is s o lv e d magnesium c o n te n t i n s tre a m s . +2 A cc ep tin g t h i s , i t w ould fo llo w t h a t o n ly a p a r t o f th e incom ing M g w ould have t o b e rem oved, o r c o u ld be e x p e c te d to be rem oved, u n d er s ta n d a rd c o n d itio n s . The l a s t and m ost ab u n d an t io n s a r e Ha* and Cl~ ( i . e . , c h lo r i n i t y ) . A n o th er g la n c e a t T a b le I I shows t h a t f o r th e m ost p a r t th e y d o n 't show c o n s is te n t b e h a v io r , a lth o u ^ i a s l i g h t p r o c l i v i t y tow ard d e p le tio n i s a p p a re n t. D e s p ite t h i s , b o th io n s a re c o n s id e re d e s s e n t i a l l y u n r e a c tiv e . For ex am p le, B ro o k s, e t a l . ( 1968) n o rm a lize d t h e i r d a ta to Ha*. R a tio s o f th e m ajo r c a tio n s to Cl” w ere em ployed by Friedm an e t j ^ . (1 9 7 0 ), Friedm an and G avlsh (1972) and A l l , e t a l . . (1 9 7 2 ). Even w here a tr e n d i s a b s e n t, s i g n i f i c a n t v a r i a t io n s in Ha* and Cl” w ith d e p th in sed im en t have b een n o te d . S p e c i f i c a l l y , S ie v e r e t a l . , ( 196?) o b se rv e d su ch v a r i a t io n s i n c h l o r i n i t y d a ta t h a t th e y 9 t h e o r iz e d on a p o s s i b l e c a u se — em p lo y in g a membrane e f f e c t c o u p le d w ith v a r i a t i o n s in p e r m e a b ility and co m p a c tio n . As th e i n t e r s t i t i a l f l u i d i s moved u p w ard , th e y r e a s o n e d , c la y s w o u ld " f i l t e r " t h e w a te r , th u s i n c r e a s i n g c h l o r i n i t y w ith d e p th b elow th e i n t e r f a c e . F u r t h e r , t h i s upw ard m oving s o l u t i o n w ould f i n d e a s i e r p ath w ay s th ro u g h m ore p e rm ea b le l a y e r s an d h e n ce may flo w l a t e r a l l y t o l o c a t e them . C h lo r- i n i t l e s s h o u ld t h e r e f o r e in c r e a s e w ith d e p th and in m ore im perm eable l a y e r s . A c o re b a r r e l punched i n t o th e se d im e n t w ould o n ly show a v e r t i c a l p r o f i l e o f t h e Io n ab u n d an ce and p e rh a p s m iss many o f th e v a ry in g io n c o n c e n tr a tio n s w hich m ig h t o c c u r i n h e te ro g e n e o u s s e d im e n t. T hese e f f e c t s c o u ld a l t e r t h e m easu red c o n c e n tr a tio n s o f o th e r io n ic s p e c ie s a s w e l l . A m ore d e t a i l e d e x p la n a tio n o f th e membrane e f f e c t may b e fo u n d i n W hite (1 9 6 M . A d i f f e r e n t e x p la n a tio n f o r e r r a t i c C l" v a lu e s was g iv e n by Ben-Y aakov (1 9 7 2 ), who p ro p o se d t h a t an Io n c o u p lin g e f f e c t , t o s a t i s f y th e re q u ire m e n ts o f e l e c t r i c a l n e u t r a l i t y , c o u ld c a u se l o c a l v a r i a t i o n s i n C l" v a lu e s . In sum , p e r t u r b a t i o n s i n c h l o r i n i t y p r o f i l e s may n o t c a r r y im p lic a tio n s o f d i a g e n e a l s , a n d , a s a c o r o l l a r y , some o f th e " d o g -le g s " a s s o c i a t e d w ith o t h e r p r o f i l e s o f io n c o n c e n tr a tio n s may n o t b e w h o lly a t t r i b u t a b l e t o d la g e n e tlc r e a c t i o n s . P e rh a p s t h e m o st c r i t i c a l s p e c ie s t o b e i n v e s t i g a t e d i s s i l i c a (S iO ^ w h ic h h a s become th e c e n t e r o f c o n s id e r a b le c o n tr o v e r s y w ith r e g a r d t o i t s b u f f e r c a p a c ity and i t s im p o rta n c e i n t h a t r o l e . A m u ltitu d e o f o b s e r v a tio n s ( e . g . , S l e v e r , 1 9 6 5 , B is c h o f f and Ku, 1 970; B is c h o f f and Ku, 1971* B is c h o ff and S a y le s , 1 9 7 2 ; S k o lk o v ltz , 1 9 7 2 ; M u rray , 1973) i n d i c a t e t h a t s i l i c a i s c h a r a c t e r i s t i c a l l y e n r ic h e d i n 10 I n t e r s t i t i a l w a te r r e l a t i v e t o b o tto m w a te r , d e s p it e a r t i f i c i a l l y h ig h v a lu e s a s s o c ia te d w ith te m p e ra tu re o f s q u e e z in g e f f e c t s (F an n in g and P l l s o n , 1 9 7 1 ). T h is i s u n d o u b te d ly r e l a t e d to a s i l i c a s o u rc e in a s o l u t i o n u n d e r s a tu r a te d w ith r e s p e c t to s i l i c a . E x p e rim e n ta l work (M ack en zie, e £ a l . , 1967) c o n firm s t h i s phenom enon: s e a w a te r d e f i c i e n t i n s i l i c a and in th e p re s e n c e o f v a r io u s c la y m in e r a ls d i s p la y e d a r e l a t i v e I n c r e a s e in s i l i c a c o n c e n tr a tio n . C o n v e rs e ly , en r ic h e d s e a w a te r l o s t s i l i c a to c la y s . M o reo v er, M ackenzie and Gees (1971) d e m o n stra te d th e p o s s i b i l i t y o f q u a r tz p r e c i p i t a t i n g d i r e c t l y from s e a w a te r; an e v e n t h e r e to f o r e n o t c o n s id e re d l i k e l y enough to w a rra n t s e r io u s c o n s id e r a t i o n . T h is e x p e rim e n ta l w ork h a s a d i r e c t b e a r in g on th e p ro b le m s o f e a r l y d ia g e n e s is . I f c la y m in e ra ls o r am orphous a l u m i n o s l l i c a t e s can ta k e up s i l i c a , th e n a l t e r a t i o n from one c la y ty p e to a n o th e r can o c c u r. A u th lg e n lc c la y s may a l s o fo rm . T h is l i n e o f r e a s o n in g was fu n d a m en ta l i n th e t h e o r ie s d e v e lo p e d by S l l l e n (1 9 6 1 ), C a r r e l s , (1 9 6 5 ), M ackenzie and G a r r e ls (1966) and H e lg e so n , G a r r e ls , and M ackenzie (1 9 6 9 ). P re v io u s f i e l d e v id e n c e s u p p o r tin g t h e i r c o n c e p ts was p ro d u ced by B ie n , e £ a l . , (1 9 5 8 ), who s t a t e d t h a t m ost o f th e s i l i c a d e liv e r e d by th e M is s is s ip p i R iv e r was i n o r g a n ic a l ly rem oved. L is s and S p en cer (1970) and L ie s and P o ln to n (1973) h av e shown t h a t up to 30X o f th e d is s o lv e d SIO2 in s tre a m s may be rem oved upon e n t e r i n g s e a w a te r in some E n g lis h e s tu a r i e s . C o n v e rs e ly , S te fa n s s o n and R ic h a rd s (1963) found no e v id e n c e f o r s i g n i f i c a n t in o r g a n ic rem o v al o f s i l i c a a t th e m outh o f th e Colum b i a R iv e r; a c o n c lu s io n s u p p o rte d by th e r e s e a r c h o f R y th e r, e t a l . . (1 9 6 7 ), who w orked o f f s h o r e o f th e Amazon R iv e r , and S ch ln k (1967) 11 who a n a ly z e d th e s i l i c a b u d g et o f t h e M e d ite rra n e a n . The l a s t th r e e in v e s t i g a t i o n s le n d s u p p o rt t o th e id e a s o f S ie v e r (1 9 6 8 ), B ro e c k er (1 9 7 1 ). C a lv e rt (1 9 6 8 ), F anning and S chink (1 9 6 9 ), H eath ( i n p r e s s ) , and P ytkow icz (1967)* A ll o f th e s e r e s e a r c h e r s , though n o t denying th e th e o r ie s o f th e f i r s t s c h o o l, im ply t h a t in o rg a n ic rem o v al o f s i l i c a may b e i n s i g n i f i c a n t . In g e n e r a l, th e y em phasize th e im pact t h a t s i l i c e o u s o rg an ism s c o u ld have i n c o n tr o l o f s i l i c a f lu x . B oth H eath ( in p r e s s ) and W o lla st ( in p r e s s ) have w orked o u t s i l i c a bud g e ts f o r th e s e a . These a u th o rs a g re e t h a t s i l i c a i n th e w a te r column i s la r g e l y c o n tr o lle d by o rg a n ism s, b u t W o lla st ta k e s a d iv e r g e n t view w ith re g a rd t o th e im p o rt i n th e se d im e n t. He f e e l s t h a t i n t e r s t i t i a l w a te r s i l i c a may r e a c t w ith th e v a r io u s s o l i d p h a se s t o a con s id e r a b le d e g re e . A nother enigm a a s s o c ia te d w ith s i l i c a i n o c e a n ic and p o re w a te rs i s t h a t i t i s u n d e r s a tu r a te d w ith r e s p e c t t o o p a lin e B i l l c a . M orey, e t a l . , ( 1962) d ete rm in e d t h a t f o r norm al se a w a te r te m p e ra tu re s th e s i l i c a e q u ilib riu m c o n c e n tr a tio n s h o u ld be ab o u t 60 ppm. T h at i s , ^ ( - o r p h ) + 2H 2° " V IOMA,) w here Kgp - ^ s i O ^ 1 x 10 T h e re fo re , i n o r d e r t o p r e c i p i t a t e am orphous s i l i c a ( s i l i c a g e l) th e c o n c e n tr a tio n o f H^SIO^ w ould have to ex ceed th e a fo re m e n tio n e d v a lu e a lth o u g h d is s o lv e d s i l i c a v a lu e s r a r e l y e x c ee d 30 ppm i n th e norm al m arin e en v iro n m e n t. I n t e r s t i t i a l w a te r v a lu e s in s i l i c e o u s o ozes can a t t a i n 50 t o 60 ppm and h ig h e r , b u t th e s e c o n c e n tr a tio n s seldcm a re found in such e n v iro n m e n ts. I t h a s been s u g g e s te d t h a t th e r e le a s e 12 o f s i l i c a I n th e s e a re a s h a s been I n h ib i t e d by a c o a tin g o r m asking e f f e c t . W hether th e arm or i s g i b b s i t e (W o lla s t, 1 9 6 5 ), s e p l o l i t e (B is c h o ff and S a y le s , 1 9 7 2 ), some o th e r in o rg a n ic s u b s ta n c e , o r p e r h ap s an o rg a n ic s h e a th , a s u b tle c o n tr o l o f s i l i c a r e l e a s e may be p r e s e n t. W hatever th e c a s e may b e , th e r o le o f s i l i c a in d ia g e n e s is and i t s b u f f e r in g c a p a c ity rem ain l a r g e l y unknown q u a n t i t i e s . S tudy A rea T h ree b a s in s in th e S o u th e rn C a lif o r n ia C o n tin e n ta l B o rd e rla n d w ere chosen f o r Btudy (F ig . l ) . These b a s in s em brace a sp ectru m o f p h y s ic a l and ch em ical en v iro n m en ts in c lu d in g b a s in f lo o r s o f v a ry in g d e p th s (c o re s A E 16991, 16996, 17607 and 1 7 8 1 1 ), b a s in s lo p e s , su bm arine can y o n s, (AHF 1699**), fa n sy stem s (AHF 1699*0, and sandy a re a s (c o re AHF 18U3 6 ) . T h is re g io n a ls o i s s u b je c t t o changes in s e d im e n ta tio n r a t e , and c o n ta in s b o th o x id iz in g and re d u c in g e n v iro n m e n ts. S a n p lin g th e s e d iv e r s e en v iro n m en ts p e rm it th e ran g e o f con d itio n s i n a norm al m arin e en v iro n m en t t o be b r a c k e te d w ith r e s p e c t t o th e s e v e r a l v a r i a b l e s . Emery ( i 9 6 0 ) h as d e s c rib e d th e b o r d e rla n d i n d e t a i l , and th e r e a d e r i s r e f e r r e d t o t h a t work f o r a more com plete tre a tm e n t o f th e p h y s io g ra p h ic , s e d im e n to lo g ic a l, and o ce an o g ra p h ic c o n d itio n s o f t h i s c o n tin e n ta l m arg in a r e a . I t h a s been p o s tu la te d by s e v e r a l a u th o rs ( e . g . , H e a th , i n p r e s s ) t h a t th e c o n tin e n ta l m arg in s may be th e m ost c h e m ic a lly a c tiv e a r e a s , and th e s tu d y a r e a chosen co m p iles w ith t h i s c r i t e r i o n as w e ll. F ig u re 1 . S ta tio n L o c a tio n s and g e n e r a l a r e a o f study* Sam ples d e s ig n a te d by A lla n Hancock F o u n d atio n S ta tio n Num bers. 13 BATHYMETRY ond STATION LOCATIONS K M C O N T O U lt L a stly * th e o u te r b a s in s a r e e s s e n t i a l l y f r e e from p o l l u t i o n by sewage o u t f a l l s and a r e o f f th e s h ip p in g la n e s and h ence c o u ld y i e l d In fo rm a tio n f o r th e m ost p a r t d e v o id o f th e d i r e c t e f f e c t s o f m an 's a c t i v i t i e s . Acknowledgments I am d e e p ly in d e b te d t o D r. Donn S . G o rs lin e o f th e D epartm ent o f G e o lo g ic a l S c ie n c e s , U n iv e r s ity o f S o u th e rn C a lif o r n ia . H is en co u rag em en t, s u p p o r t, and in v a lu a b le commentB c o n tin u e d th ro u g h o u t th e d u r a tio n o f t h i s r e s e a r c h . D r. James L. B is c h o ff s u p p lie d h is e x p e r t i s e In th e g eo ch em ical a s p e c ts o f th e s tu d y . H is com nents on b o th p r o c e d u ra l and i n t e r p r e t a t i v e m a tte rs w ere in s tr u m e n ta l in a c h ie v in g m e a n in g fu l r e s u l t s . D r. R o b ert H. O sborne gave h i s a s s i s ta n c e i n th e s t a t i s t i c a l p h ase o f th lB work and I e x p re ss my g r a t it u d e t o him . I am a ls o th a n k f u l to D r. G ibson Reaves who rev iew ed th e m a n u s c rip t. I c a n n o t b e g in to e x p re ss my deep g r a t i t u d e t o my w if e , S andy, and d a u g h te r , " th e B ug." T h is r e s e a r c h was funded by N a tio n a l S c ie n c e F o u n d a tio n , G ran t number GA 36590. S h ip tim e was fu n d ed by N a tio n a l S c ie n c e F o u n d atio n G ran t number GB 8206. METHODS S h ip b o a rd P ro c e d u re s The p i s t o n c o re s each v e r e ta k e n frcm th e f lo o r s o f S a n ta C a ta lin a , San N ic o la s , and S a n ta Cruz B a s in s . A s e v e n th c o re was ta k e n from th e e a s te r n s lo p e o f S a n ta C a ta lin a B asin (F ig . 1 ) . A ll 7 c o re s w ere c o l l e c t e d a b o a rd th e U n iv e r s ity o f S o u th e rn C a lif o r n ia R esearch V e sse l V elero IV . T a b le I I I l i s t s th e lo c a tio n s and w a te r d e p th s f o r th e s e c o re s . Upon r e t r i e v a l th e c o re s w ere im m ed iately c u t I n to 50 cm le n g th s . On one c o re from each b a s in pH and Eh m easurem ents w ere made by d i r e c t em placem ent o f th e e le c tr o d e s i n t o th e s e d im e n t. These mea su rem en ts w ere made u s in g an O rio n Eh-pH m e te r. U n f o rtu n a te ly , no e x a c t Eh v a lu e s w ere o b ta in e d b e c a u se o f c o n s id e ra b le d r i f t o f th e i n d i c a t o r n e e d le , t h e r e f o r e , t h i s d a ta i s n o t p r e s e n te d . S u b seq u en t t o th e s e m easu rem en ts, sam ples w ere rem oved from th e c o re l i n e r s by i n s e r t i n g a m o d ifie d 50 cc p l a s t i c s y rin g e in th e sed im en t p e rp e n d i c u l a r t o th e c u t , th u s ta k in g a " s u b - c o r e ." The same p ro c e d u re was fo llo w e d on th e c o re s w hich d id n o t undergo pH d e te r m in a tio n s . The sam ple I n t e r v a l was t h e r e f o r e e v e ry 50 cm in c lu d in g to p and b o tto m . The " s u b -c o re s " w ere th e n e x tru d e d d i r e c t l y I n to g la s s j a r s and k e p t a t i n s i t u te m p e ra tu re (U°C) i n o rd e r t o a v o id th e e f f e c t s o f changes in te m p e ra tu re on p o re w a te r c o m p o sitio n ( B is c h o f f , e t a l . 1970; 16 17 TABLE I I I C ore l o c a t i o n s an d v a t e r d e p th s ALLAN HANCOCK FOUNDATION STATION NUM BERS COORDINATES tm'M U A L AREA 16991 1699! * 16996 16997 17807 17811 101*36 L a t. 33°13'1*5m N. Long. l l f l ° 2 0 ' 00**W . L a t. 33°V r*09"N . Long. l ^ f i l ' O S ^ . L a t. 33°10'3O "N . Long. U0°1*O'OO"W. L a t. 3 3 °2 6 , 15”N. Long. 118°U 0’ 00,,W. L a t. 32°52'U 0"N . Long. 1 1 9 °5 3 ’ 20”W. L a t. 33°3l*, 30"N. Long. 1 1 9 °2 8 , 00"W. L a t. 3 3 °1 3 ’ ?1*"N. Long. 110°1O'2O"W. San N ic h o la s B a sin S a n ta C ruz B a sin S a n ta C a ta lin a B a sin S a n ta C a ta lin a B a sin San N ic h o la s B a sin S a n ta C ruz B a sin S a n ta C a t a l i n a B a sin DEPTH 1750 1875 1300 960 1750 1850 1025 18 F an n in g and P l l s o n , 1 9 7 1 ). The sam p les w ere s to r e d In t h i s c o n d itio n u n t i l rem o v al o f th e I n t e r s t i t i a l w a te r c o u ld be a c c o m p lish e d . The I n t e r s t i t i a l w a te r was sq u ee z ed from th e se d im e n t u s in g an a p p a r a tu s d e s ig n e d by K a l i l and G o ld h sb e r (1 9 7 3 ). The c y l i n d r i c a l " s u b - c o r e " was dumped I n to th e s q u e e z in g cham ber from th e g l a s s J a r s o r , when n e c e s s a r y , was rem oved from th e j a r w h ile w e a rin g p l a s t i c g lo v e s to a v o id c o n ta m in a tio n by p e r s p i r a t i o n . In f a c t , th e sam p les w ere n e v e r to u c h e d by hand p r i o r t o o r a f t e r th e rem o v al o f th e p o re w a te r b e c a u s e o f th e l i k e l i h o o d o f c o n ta m in a tio n . T h is p r e c a u tio n i s p a r t i c u l a r l y Im p o rta n t w ith r e g a rd t o c h l o r l n l t y a n a ly s e s (R. S ie - v e r , p e r s o n a l co m m u n ic a tio n ). The sed im e n t was th e n sq u e e z e d u s in g a S e a rs 3 to n h y d r a u lic hand ja c k (Model No. 7 2 7 .1 2 4 1 1 ) a t a v e ry low p r e s s u r e , p ro b a b ly n o t e x c e e d in g 250 P S I and c e r t a i n l y n o t e x c e e d in g 500 P S I. S q u eezin g p r e s s u r e m ust be k e p t low to p re v e n t s a l t - f i l t e r in g e f f e c t s and even th e p r e s s u r e UBed h e r e may be to o g r e a t (P a ra - s h iv a , M u rth y , and F e r r e l l , 1 9 7 2 ). At t h i s low p r e s s u r e up to 90Z o f th e p o re w a te r was fo rc e d o u t and i n t o p l a s t i c s y r in g e s . T h is i n i t i a l volum e o f p o re w a te r , a b o u t 15 m l, w hich had a lr e a d y p a s se d th ro u g h a Whatman No. 50 f i l t e r p a p e r , was f i l t e r e d a g a in ; t h i s tim e th ro u g h a m i l l l p o r e f i l t e r w ith a mean p o re s i z e o f 0.22 m ic ro n , in o r d e r to in s u r e t h a t th e a l i q u o t was f r e e from any e f f e c t s due to th e p re s e n c e o f su sp en d ed se d im e n t and o th e r p a r t i c u l a t e m a tte r . The sam p les w ere i n j e c t e d I n to p l a s t i c v i a l s , th e v i a l s s e a le d t i g h t l y and r e f r i g e r a te d u n t i l th e v a r io u s a n a ly s e s c o u ld b e p e rfo rm e d . T h is e n t i r e p r o c e s s , from rem o v al o f th e sam ple from th e r e f r i g e r a t o r u n t i l ex p u ls io n o f th e p o re w a te r toom 2 to 4 m in u te s . I t i s b e lie v e d t h a t 19 no s i g n i f i c a n t r i s e in te m p e ra tu re o c c u rre d d u rin g t h l a tim e i n t e r v a l . N e x t, th e sed im e n t was f u r t h e r sq u e ez ed u n t i l w a te r c e a s e d to flo w . The r e s u l t a n t se d im en t w a fe r was e x tru d e d and s to r e d f o r l a t e r b u lk c h e m ic a l a n a ly s e s . The tu b e s and sam ple cham ber w ere r in s e d w ith d e io n iz e d w a te r and th o ro u g h ly d r ie d in p r e p a r a tio n f o r th e n e x t sam p l e . Sam ples n o t sq u e ez e d on b o a rd w ere done so i n th e la b o r a to r y u s in g an i d e n t i c a l p ro c e d u re . A ll p o re w a te r sam p les had b ee n ta k e n w ith in 12 w eeks o f c o r in g . LABORATORY PROCEDURES P o re H a te r A tom ic A b s o rp tio n A p p ro x im a tely 4 gm o f e ac h p o re w a te r sam ple w ere e x tr a c te d from I t s v i a l w ith a s y r in g e and a c c u r a t e l y w elg n ed . T h is was com bined w ith a known w e ig h t (a b o u t 1 gm) o f c o n c e n tr a te d n i t r i c a c id to i n h i b i t p r e c i p i t a t i o n o f v a r io u s c a rb o n a te s p e c ie s w h ile th e sam ple was w arm ing t o room te m p e r a tu re . The a l i q u o t s w ere th e n d i l u t e d t o a p p ro p r i a t e c o n c e n tr a tio n s a s d i c t a t e d by th e s p e c i f i e d ra n g e s f o r th e s p e c tro p h o to m e te r. The e le m e n ts to be a n a ly z e d w ere C a, K, Mg, and Na. The d i l u t i o n s w ere done on a w e ig h t b a s i s u s in g d e io n iz e d w a te r . S ta n d a rd s w ere p re p a re d d a l l y u s in g C openhagen w a te r (C l-1 9 .3 7 4 5 o /o o ) s p ik e d w ith n i t r i c a c i d . U sing n a t u r a l s e a w a te r and n i t r i c a c id g ave th e s ta n d a r d s and sam p les an e q u iv a le n t m a tr ix . The s ta n d a r d s r e c e iv e d th e same tr e a tm e n t a s th e sam p les w ith r e g a rd t o d i l u t i o n . 20 +2 + +2 + C o n c e n tra tio n s o f Ca , K , M g , and Na v e re d e te rm in e d on th e b a s is o f 3 ru n s w ith th e 3 s ta n d a rd s b r a c k e tin g e v e ry 7 sam ples u s in g a P e rk in -E lm e r Model 303 ato m ic a b s o rp tio n s p e c tro p h o to m e te r. The +2 p r e c is io n f o r th e d e te rm in a tio n s v a s as f o llo w s ; Ca , + 1 .1 # (max- + +2 imum ran g e ab o u t r e p o r te d p e r c e n ta g e ) ; K , 0 .6 # ; M g , £ 0 . 8# , Na+ , + 3 .6 # . C o lo rim e tric S p e c tro p h o to m e try In a d d itio n t o th e U m ajo r c a tio n s i n s e a w a te r, s i l i c a was a ls o d e te rm in e d . The p ro c e d u re em ployed was a d o p ted from S tr ic k la n d and P a rso n s (1 9 6 8 ) . In t h i s m ethod s i l i c a i s a llo w e d t o combine w ith m olybdate t o form a com plex w h ich , u n d e r re d u c in g c o n d itio n s , d e v e lo p s a b lu e c o lo r . T h is c o lo r was m o n ito re d on a H ita c h i P e rk in s-E lm e r 139 UV-Vis s p e c tro p h o to m e te r. S ta n d a rd s w ere p re p a re d u s in g a r t i f i c i a l s e a w a te r and a p r o p o r tio n a te ly d il u t e d s i l i c a t e s o lu tio n . The p r e c is io n o f th e s i l i c a m easurem ents v a s + _ 0 . 8#. C h lo r ln ity T i t r a t i o n w ith s i l v e r n i t r a t e y ie ld e d c h l o r l n i t y v a lu e s . S tr ic k la n d and P a rso n s ( 1 9 6 8 ) have o u tlin e d r.he b a s ic p ro c e d u re , w hich was m o d ifie d from a v o lu m e tric t o a g r a v im e tr ic te c h n iq u e (Mohr M ethod). A w eighed amount o f i n t e r s t i t i a l w a te r (ab o u t 0 .5 g ) was in tro d u c e d i n to a sm a ll g la s s b o t t l e a lo n g w ith 5 ml d e io n iz e d w a te r , one d ro p o f n itro b e n z e n e as a d i s p e r s a n t , and one drop o f f lu o r o s c e n e , w hich was u sed a s an i n d i c a t o r . A v o r te x v a s c r e a te d i n th e b o t t l e w ith a m ag n etic s t i r r e r w ith p a r t i a l d ro p s o f 0 .1 5 Ag NO^ b e in g added w ith 21 a p l a s t i c s y rin g e and hypoderm ic n e e d le . A l a s t i n g f lu o r e s c e n t p in k i n d i c a t e s th e e n d p o in t h a s b een re a c h e d . P r e c is io n o f t h i s m ethod was + _ 0 .5% o r 0 .1 o /o o . A c id ity o f th e p o re v a t e r was m easured i n th e la b o r a to r y by an O rio n (m odel No. kO l) Eh-pH m e te r. The sam ples w ere c o n tin u a lly c i r c u l a t e d w ith a m a g n etic s t i r r e r d u rin g th e r e a d in g s . A ll sam ples w ere ru n as opposed t o th e o n ly 3 c o re s s tu d ie d on b o a rd s h ip . The agreem ent betw een th e " se d im e n t" pH w ith th e p o re w a te r v a lu e s d e t e r m ined i n th e la b o r a to r y was in a l l c a se s w ith in 1 .5%* Bu lk C h em istry X -ray F lu ro e s c e n c e The m ethod o f " f u s io n w ith a heavy a b s o rb e r" was u sed t o re a d y th e sam ples f o r a n a ly s e s on th e X -ray flu o re s c e n c e s p e c tro m e te r. A p o r tio n o f th e sq u eezed sed im en t w a fe r was d isa g g re g a te d * washed* d rie d * and w eighed to 3 0 0 .0 mg. I t was th e n m ixed i n a g r a p h ite c r u c ib le w ith 3 0 0 .0 mg Lanthanum o x id e and 7 0 0 .0 mg L ith iu m te tra n - b o r a t e . The m ix tu re was fu se d i n t o a g la s s b ead by h e a tin g t o 1000°C f o r 10 m in u te s and th e n c o o lin g . B o ric a c id was added t o b r in g th e t o t a l w e ig h t up t o 2 .0 0 g . N ext th e bead was c ru sh e d and p u t i n t o a g r in d in g v i a l w ith th e b o r ic a c id and t h e e n t i r e u n i t sh aken on a Spex m ix er f o r 10 m in u te s . The f i n a l s ta g e o f p r e p a r a tio n was to c o n s o lid a te th e r e s u l t a n t pow der i n t o a p e lle m e n t u s in g b o r ic a c id in an aluminum Spex cap as a b a se and a p p ly in g 20*000 PSI f o r 2 m in u te s w ith a h y d r a u lic p r e s s . S ta n d a rd s , ch o sen t o m atch t h e sam p les In b o th co m p o sitio n and ty p e (se d im e n ta ry m a t e r i a l ) , w ere p re p a re d i n a p a r a l l e l manner* V alues o f S lO ^, Al^O^, and K^O w ere o b ta in e d by u t i l i z i n g a N o relco X -ray flu o r e s c e n c e u n i t . Tor a l l th r e e o x id e s a P .E .T . c ry s t a l was u se d in c o n ju n c tio n w ith a tu n g s te n tu b e and a p r o p o r tio n a l c o u n te r. H elium was u sed t o f lu s h th e sam ple cham ber. C ounts w ere U 5 made i n th e f ix e d tim e mode s e t t o a llo w f o r 10 - 10 c o u n ts . The 2 I n t e r v a l was g e n e r a lly 10 s e c o n d s. F our c o u n ts w ere made f o r each sam ple and a t l e a s t one s ta n d a rd was ru n p e r t h r e e sam p les. The p r e c i s i o n f o r th e s e a n a ly s e s v a s : SIO ^, + 0 .2%; A l^O ^, +, 0 .5 $ , KgO, + 1.1$. The re m a in in g c o n s t i t u e n t s , CaO, MgO, Na^O, and Fe^O^ ( a l l ir o n v a s c a l c u l a t e d a s Fe20 ^ ) w ere done so by a to m ic a b s o rp tio n . The s o lid sam ple was w eig h ed , t r a n s f e r e d t o a t e f l o n b e a k e r , end fumed w ith h y d r o f lu o r ic a c id and p e r c h lo r ic a c id on a h o t p l a t e . The e x a c t te c h n iq u e may be found in B i l l i n g s (1 9 7 0 ). When d ry n e ss was a c h ie v e d th e r e s id u e was ta k e n up w ith 6N h y d ro c h lo ric a c id and d i l u t e d t o a c o n c e n tr a tio n e s tim a te d t o b e w ith in th e c o r r e c t ran g e f o r th e atom ic a b s o rp tio n u n i t . S ta n d a rd s u se d w ere e i t h e r d i l u t e d com m ercial s to c k s o lu tio n s (Mg, F« ) o r p re p a re d from r e a g e n ts (C a, H a). HC1 was added to a t t a i n m a trix p a r i t y w ith t h e sam p le s. The same te c h n iq u e s w ere em ployed on th e a p p a ra tu s a s v a s d is c u s s e d p r e v io u s ly . W ith th e s e a n a ly s e s t h e p r e c i s i o n v a s : CaO, + 1 .9 $ , MgO, + _ 0 .6 $ ; Na^O, Amorphous M a te ria l 23 The b a s ic m ethod u s e d f o r t h e d e te r m in a tio n o f p e r c e n t amorphous m a te r ia l ( i . e . , amorphous t o X -ra y s) v a s t h a t d e s c rib e d by F o l l e t , e t a l> , (1 9 6 5 ). A ppro x im ately 100 mg o f 62 m icro n sam p le, a c c u r a te ly v e ig h e d , v a s p la c e d i n a 50 ml c e n tr if u g e tu b e . In o rd e r t o accom p l i s h d is p e r s io n and remove c a rb o n a te s 35 ml sodium a c e ta te s o lu tio n b u f f e r e d t o a pH o f 5 v a s in tro d u c e d i n t o th e tu b e s . The c o n te n ts w ere th e n a g i t a t e d and h e a te d t o T5°C on a steam b a th . A fte r 30 min u te s o f p e r io d ic s t i r r i n g t h e sam ple v a s "spun-dow n" on th e c e n tr if u g e a t 2000 r .p .m . D e c a n ta tio n o f th e s u p e rn a te n t l i q u i d v a s p erfo rm ed and th e p ro c e d u re r e p e a te d u n t i l no e ffe r v e s c e n c e was o b s e rv e d i u s u a lly one r e p e t i t i o n v a s s u f f i c i e n t . A fte r d ig e s tio n o f th e c a r b o n a te s , th e sed im en t v as w ashed w ith h o t d i s t i l l e d w a te r , c e n tr if u g e d , and th e w a te r d e c a n te d . In o r d e r t o remove o rg a n ic m a te r ia l 6jt Hydrogen P e ro x id e v a s added t o th e tu b e s and a p ro c e d u re I d e n t i c a l t o th e sodium a c e ta te tre a tm e n t em ployed. Once a g a in , o n ly 2 a p p lic a tio n s w ere n e c e s s a ry . Next th e sam ples w ere t r e a t e d w ith ammonium a c e t a t e , a n d , a f t e r s i t t i n g o v e r n ig h t, th e c e n t r i f u g a t i o n p ro c e s s v a s u se d t o remove th e l i q u i d p h a s e . None o f th e w ash in g s up t o t h i s p o in t w ere sa v ed f o r a n a l y s is . F o l l e t t , e t a l . , (1965) r e p o r te d t h a t th e s e HgOg w ash in g s from h is own sam ple c o n ta in e d an i n s i g n i f i c a n t amount o f S i and A l . I t i s assum ed t h a t th e sodium a c e t a t e w ash in g s v e r e lik e w is e d ev o id o f r e p o r ta b le am ounts o f th e s e e le m e n ts c h i e f l y on th e s tr e n g th o f th e pH v a lu e ( 5 ) , w hich w ould n o t prom ote d i s s o l u t i o n o f e i t h e r SiO^ o r A I 2 O3 . 24 Amorphous m a t e r ia l was rem oved by d i g e s t i o n w ith 5% NSjCO^* To each c e n t r i f u g e tu b e 35 ml s o l u t i o n was added an d a llo w e d t o r e s t u n d is tu r b e d f o r 20 h o u r s . A f te r c e n t r i f u g a t i o n th e s u p e r n a te n t l i q u i d was d e c a n te d i n t o a p o ly e th y le n e b o t t l e . T h is s te p was re p e a te d o n c e . Hot 5% N&2C0^ tr e a tm e n ts w ere a p p lie d tw ic e fo llo w in g th e c o ld tr e a tm e n ts . A te m p e ra tu re o f 75°C and a tim e i n t e r v a l o f 2 h o u rs w ere u s e d . T hese w ash in g s w ere com bined w ith th e e a r l i e r o n e s . A c c o rd in g to F o l l e t , e £ a l . , (1 9 6 5 ), th e " c o ld " s o lu t i o n seem s to be more e f f e c t i v e in le a c h in g am orphous SiO ^, w h ereas th e " h o t" s o l u t i o n rem oves more am orphous A ljO ^. O nly two ru n s o f each w ere done to m in i m ize th e a t t a c k on th e s t r u c t u r e d s i l i c a t e s . Amorphous SIO2 was d e te rm in e d c o l o r i m e t r i c a l l y u s in g th e m olyb- d a te te c h n iq u e a s b e f o r e . The p r e c i s i o n was ±0.6% . Amorphous alum inum was a n a ly z e d em p lo y in g th e m ethod o f R a in w a te r and T h a tc h e r (1 9 6 0 ). T h is te c h n iq u e u t i l i z e s a com plex form ed b etw een alum inum and F e r r o n - o r th o p h e n a n tr o lin e . The e x te n t o f fo rm a tio n o f t h l e com p le x can be m easured in th e u l t r a v i o l e t ra n g e by a c e l l s p e c tr o p h o to m e te r. S ta n d a rd s w ere p re p a re d from a s to c k alum inum s o l u t i o n . A m ajo r encum brance o f t h i s te c h n iq u e i s th e e p h lm e ra l n a tu r e o f th e com plex, w hich b re a k s down in 30 m in u te s . F u rth e rm o re , th e co m p lex in g may be e r r a t i c o v e r t h a t 30 m in u te s , a s im p lie d by th e c a l c u l a t e d p r e c i s i o n : +14.4% . In one in s ta n c e th e r e p r o d u c i b i l i t y was no b etw een th a n 25%, T h is a n a l y s is was done on one c o re from e ach b a s in , a s was th e d e te r m in a tio n o f f r e e i r o n . “F ree I r o n ” 25 C o n tig u o u s w ith th e tre a tm e n t o f sam ples t o rem ove amorphous m a t e r ia l, " f r e e ” ir o n o x id e s w ere a ls o rem oved. These o x id e s , w hich p ro b a b ly c o n s is t o f h e m a tite and g o e t h i t e , e x i s t a s c o a tin g s on th e in d iv id u a l g r a in s and a r e n o t bound s t r u c t u r a l l y t o th e m in e ra ls w hich th e y s h e a th . The p ro c e d u re o f Ja c k so n (1956) was ad o p ted f o r th e d i s s o l u t i o n o f th e s e c o a tin g s . T h is m ethod was im plem ented su b se q u en t t o th e le a c h in g o f th e am orphous m a te r ia l b e ca u se o f th e g r e a t e r e f f i c i e n c y o f ir o n rem oval i f th e two m ethods a r e done i n t h i s seq u en ce ( F o l l e t t , e t a l . , 1 9 6 5 ). B a s ic a lly , ir o n e x t r a c t i o n i s acco m p lish e d by r e d u c tio n w ith sodium d ith lo n iv e and c h e la tin g th e r e le a s e d m e ta l io n s w ith sodium c i t r a t e . As p o in te d o u t by Ja c k so n (1956) t h i s m ethod I s e x tre m e ly e f f e c t i v e in t h a t i t i s r a p id (15 m in u te s) and does n o t a llo w p r e c i p i t a t i o n o f i r o n s u l f i d e s . A lthough Ja c k so n (1956) recommends th e u se o f a c e to n e as a f lo c c u l a t in g a g e n t a f t e r d ig e s tio n , i t was n o t u se d due t o i t s v o l a t i l e n a tu r e . T h is was nec e s s a r y b e ca u se a f t e r c e n t r i f u g a t i o n and d e c a n ta tlo n th e le a c h a te was to be a n a ly z e d by ato m ic a b s o rp tio n . The p r e c is io n f o r t h i s p h a se was + 1 .2 $ . M in eralo g y C lay M in e ra ls P r e p a r a tio n o f th e sed im en t f o r c la y m in e ra l a n a ly s e s was done by th e p ro c e d u re d e lin e a te d by Ja c k so n (1 9 5 6 ). B eing ro u g h ly a n a lo gous t o e a r l i e r tr e a tm e n ts f o r th e e x t r a c t i o n o f am orphous m a te r ia l 2 6 and " f r e e i r o n § " t h e p rim in g o f t h e c la y s f o r X -ra y s tu d y was i n i t i a t e d 'by w et s ie v in g ab o u t 10 gm ( d ry ) o f sam ple t o s e p a r a t e t h e 62 m icro n s i z e f r a c t i o n . The e n t i r e f in e f r a c t i o n was u s e d i n o r d e r t o o b ta in r e s u l t s on t o t a l m in e ra lo g y . The s i l t - c l a y f r a c t i o n was th e n p la c e d i n 250 m l b e a k e rs and t h e c a rb o n a te rem oved b y a d d in g 150 - 200 ml pH-5 sodium a c e t a t e . The b e a k e rs w ere h e a te d t o 75°C t th e c o n te n ts t r a n s f e r r e d t o c e n t r i f u g e tu b e s , an d t h e s u s p e n s a te b ro u g h t down b y c e n t r i f u g a t i o n a t 2000 r .p .m . The s u p e r n a te n t l i q u i d was p o u re d o f f and t h e e n t i r e p r o c e s s r e p e a te d u n t i l t h e fo am in g c e a s e d . U s u a lly one o r tw o r e p e t i t i o n s was s u f f i c i e n t . S i m i l a r l y , 6% HgOg was u s e d to rem ove t h e o r g a n ic m a tte r and t h e p r e v io u s ly d is c u s s e d m ethod f o r rem oving " f r e e " i r o n o x id e s was em ployed. F i n a l l y , a f t e r t h r e e w a sh in g s w ith d i s t i l l e d w a te r , t h e se d im e n t s l u r r y was th e n a p p lie d t o p o r c e l a i n s l i d e s t o p ro d u c e o r i e n t e d m ounts f o r a n a ly s e s by X -ray d i f f r a c t i o n . V ig o ro u s s t i r r i n g s o f th e s l u r r y was fo llo w e d by e x t r a c t i o n o f an a l i q u o t w ith an a u to m a tic p i p e t t e , and th e n q u ic k ly and e v e n ly d e p o s itin g th e s l u r r y on a p o ro u s ce ram ic t i l e (B is q u e , o r o n c e - f i r e d t i l e ) . Two m ounts o f e a c h sam ple w ere made i n t h i s f a s h io n . Sub s e q u e n tly , one s e t o f m ounts was p la c e d i n a d i s s l c a t o r and h e a te d f o r 4 h o u rs a t 65°C i n t h e p r e s e n c e o f e th y le n e g l y c o l . The o th e r s e t was h e a te d t o 600°C f o r 1 h o u r. F l e i s c h e r (1 9 7 0 ) i d e n t i f i e d th e c la y m in e r a ls p r e s e n t I n t h e b o r d e r la n d , and h i s d e t a i l e d i n v e s t i g a tio n p r o v id e d a fram ew ork f o r t h e a n a ly s e s made i n t h i s s tu d y . Thus i t was o n ly n e c e s s a r y t o u n d e r ta k e t h e q u a n t i t a t i v e a s p e c t o f th e c la y m in e ra lo g y , t h e e x a c t s p e c ie s a lr e a d y b e in g known. The t r e a t e d t i l e s 27 w ere scan n ed a t 2° 2 O/min on a K o relco X -ray d if f r a c to m e te r from 3° t o 15° u s in g CuK r a d i a t i o n . Of th e c la y s r e p o r te d by F le is c h e r ( 1 9 7 0 ) o n ly c h l o r i t e , l l l i t e , k a o l i n l t e , and m o n tm o rillo n lte w ere d e term in e d q u a n t i t a t i v e l y . I n t e n s i t i e s w ere r e s o lv e d by m ea su rin g p eak a r e a s w ith a p la n im e te r. B ackground i n t e n s i t y v a s d e f in e d on th e d iff r a c to g ra m u s in g a F rench c u rv e . The s p e c i f i c p eak s u se d w ere th e 600°C lUA peak f o r c h l o r i t e , th e g ly c o la te d 10A p eak f o r l l l i t e , th e 7 -5 A g ly c o la te d peak f o r k a o l i n l t e , and th e 16 A g ly c o la te d peak f o r m o n tm o rillo n lte . For a more th o ro u g h d is c u s s io n o f i d e n t i f i c a t i o n and e s tim a tio n o f c la y m in e ra l p e r c e n ta g e s , th e r e a d e r i s r e f e r r e d t o C a r r o ll (1 9 7 0 ). The m easured i n t e n s i t i e s w ere c o n v e rte d t o p e r c e n ta g e s by u t i l i z i n g t h e e q u a tio n d ev elo p ed by F le is c h e r (1 9 7 0 ). S in c e t h i s e q u a tio n was c o n s tr u c te d s p e c i f i c a l l y f o r che se d im e n ts in th e b o rd e rla n d i t 1 b assum ed t o b e v a l i d f o r t h i s s tu d y . The fo rm u la i s : X,% * 100 c /3 + k /2 + I + M/i* w here X ■ r a t i o p e r c e n t o f any in c lu d e d c la y p h ase P ■ any o f th e c la y p h a se s i n th e d enom inator k - th e c o rre sp o n d in g i n t e n s i t y o f t h a t c la y p h ase C ( c h l o r i t e ) ■ lh A - 600° p eak a r e a K ( k a o l in l t e ) * 7 A - g ly c e r o l p eak a r e a - S(1^A° - 600° peak a re a ) 3 I ( l l l i t e ) ■ 10A g ly c e r o l p eak a r e a M (m o n tm o rillo n lte ) ■ 18A g ly c e r o l p eak a r e a V e rm lc u llte v as n o t d e te rm in e d and h ence v a s e lim in a te d from th e fo rm u la . 26 A p p lic a tio n o f t h i s e q u a tio n , b e a r in g I n m ind t h a t th e 62 m icro n f r a c t i o n v a s u s e d , h as a lo n g te rm r e p r o d u c i b i l i t y o f _ + 20$ f o r a l l c la y p h a s e s. ffon-C lay M in e ra ls The n o n -c la y m in e ra ls i n th e 62 m icro n f r a c t i o n v e r e d e te rm in e d on a q u a l i t a t i v e b a s i s . From th e sam ples p re p a re d f o r c la y m in e ra l a n a l y s i s , a t h i r d m ount was made on a g la s s s l i d e r a t h e r th a n a c e r a m ic t i l e . S tro n g I n te r f e r e n c e i n th e q u a r tz - f e l d s p a r ra n g e by th e t i l e s made th e u se o f g la s s m an d ato ry . The s l i d e s v e r e scan n ed from 10° t o 30° 0 a t 2° 2 0 /m in . CuK r a d i a t i o n v a s a g a in u s e d . Q u artz v a s i d e n t i f i e d by i t s k,26 A and 3.3U A p e a k s . K -fe ld s p a r and p la g io - c la s e v e re in d ic a te d by th e p re s e n c e o f p eak s a t 3 .1 8 A and 3>2b A. Am phibole p ro d u ced a h ig h i n t e n s i t y peak a t S.ltA. T h is s u i t e o f non c la y m in e ra ls i s i d e n t i c a l t o t h a t fo u n d by F le is c h e r (1 9 7 0 ). T e x tu r a l A n a ly sis Mean d ia m e te r and s o r t i n g valueB f o r th e sed im en t v e re dellnea~- t e d u s in g a co m b in atio n o f s ie v e s and h y d ro m eter a n a l y s is . The sa m p le s, w hich ex ceed 25 gms v e t w e ig h t, w ere f i r s t v e t s ie v e d t o s e p a r a te th e c o a rs e ( 62 m ic ro n s) and f in e f r a c t i o n s . The san d f r a c t i o n v a s th e n p a r t i t i o n e d and a n a ly z e d w ith s ie v e s . The f i n e f r a c t i o n s iz e d i s t r i b u t i o n v a s d e te rm in e d u s in g a s o i l h y d ro m e te r. The c la y s v e re p re v e n te d from f l o c c u l a t i n g by u s in g a v e ry d i l u t e m a ra sp e rse s o lu tio n i n d i s t i l l e d v a t e r i n g ra d u a te d c y lin d e r s . A " z e ro w e ig h t" o r z e ro tim e e la p s e d re a d in g o f th e h y d ro m eter v a s i n e f f i c i e n t , so t h e t o t a l w e ig h t o f t h e sam ple v a s a s c e r ta in e d hy d ry in g t h e sam ple and w e ig h in g . Smear Mounts Smear m ounts v e r e exam ined w ith a p e tr o g ra p h ic m ic ro sc o p e . Sam ples from one c o re from each b a s in w ere scan n ed w ith th e fo llo w in g c la s s e s re c o g n iz e d : flo c k B , q u a r t z , f e l d s p a r , h o rn b le n d e , sponge s p e c u le s , f o r a m in if e r a , r a d l o l a r i a n s , and B h e ll fra g m e n ts ( c h i e f l y b ry o z o a n s ). R e la tiv e p e rc e n ta g e s w ere e s tim a te d , b u t o n ly t o an o r d e r o f m ag n itu d e. PORE W ATER CHEMISTRY M ajor C a tio n s +2 Of th e fo u r io n s i n t h i s c a te g o r y , o n ly Mg shove a p r e f e r r e d tr e n d (T ig . 2 - 8 ) . T hat tr e n d i s t o d e c r e a s e , and i t does t h i s i n f iv e o f th e sev en c o r e s . However, th e tr e n d s a r e so s u b tle i n m ost c a s e s t h a t ev en t h i s io n can n o t h e s a id t o p o s s e s s more th a n an appa^- +2 + + r e n t te n d e n cy to w ard d e p le tio n . None o f th e o th e r io n s (Ca , K , Na ) d is p la y even t h i s c o n s is te n c y o f b e h a v io r , i n d i c a t i n g t h a t i n th e v a r i e t y o f p h y s ic a l en v iro n m e n ts sam pled no c a tio n shows a p r e fe r e n c e o f t r e n d . Com parisons t o b o tto m w a te r v a lu e s p u b lis h e d by Etoery ( i 9 6 0 ) i n d ic a te t h a t a c t i v i t y i s o c c u rrin g d e s p ite th e la c k o f tr e n d s . In ++ f a c t , o n ly Ca exh l b l t s an e n d u rin g p a r i t y betw een th e c o n c e n tr a tio n a t th e to p o f th e c o re and i n th e b o tto m w a te r. K + p a r t i c u l a r l y , c o n s is t e n t l y shows en ric h m e n t o v e r th e p r e d ic te d v a lu e . T h is e n r ic h m en t, w hich can ex ceed 50Jf, i n d i c a t e s a trem endous upw ard f lu x from th e s e d im e n t. A s im i l a r c irc u m sta n c e was o b serv ed by M urray (1973) and H u lb e rt and G iven ( i n p r e p a r a tio n ) among o th e r s . Im balance a ls o e x i s t s betw een bottom w a te r v a lu e s and to p s o f c o re v a lu e s f o r 4 2 +2 M g and Na th e fo rm er s l i g h t l y h ig h e r and th e l a t t e r b e in g g e n e r a lly low er th a n th e s t r a i g h t s e a w a te r c o u n te r p a r t. 30 F ig u re 2 . M ajor c a tio n tr e n d s ( c o n c e n tra tio n i n sam ple v s . d e p th ): Core 16991 Bottom v a t e r c o n c e n tr a tio n s f o r t h i s c o re : Ca, .1*0 o /o o ; K, .38 o /o o ; Mg, 1 .2 8 o /o o ; Na, 1 0 .5 8 0 /0 0 (Em ery, I9 6 0 ) 31 depth i n core (CM) C oncentration o f Major Cations ( % • ) I C Q Q I Ca K Mg Na 100- 200. 3 0 0 - F ig u re 3* M ajor c a t i o n tr e n d s ( c o n c e n tr a tio n in sam ple v s . d e p th ) . C ore 1699^ B ottom v a t e r c o n c e n tr a tio n s f o r t h i s c o re : C a, .UO o /o o ; K, .3 6 o /o o ; Mg, 1 .2 8 o /o o ; N a, 1 0 .6 l 0 /0 0 (Emery i 9 6 0 ) 33 m Concentrations of Major Cations ( % • ) 16994 Ca K Mg Na I 100 w * 0 200 3 0 0 F ig u re U. M ajor c a tio n tr e n d s ( c o n c e n tr a tio n i n sam ple v s . d e p th ) . Core 16996 B ottom v a t e r c o n c e n tr a tio n s f o r t h i s c o re : Ca, . Uo o /o o ; K, .3 8 o /o o ; Mg, 1 .2 8 o /o o ; If a , 1 0 .6 1 o /o o (Emery i 9 6 0 ) 35 depth I n core (CM) Concentrations of Major Cations ( % • ) I C Q Q C Ca K Mg Na 100 * 200. 3 0 0 - F ig u re 5 . M ajor c a tio n tr e n d s ( c o n c e n tr a tio n i n sam ple v s . d e p th ) . Core 1699T Bottom w a te r c o n c e n tr a tio n s f o r t h i s c o re : C af .1*0 o /o o ; K, *36 o /o o ; Mg, 1 .2 8 o /o o ; N a, 1 0 .6 l 0 /0 0 (Emery i 9 6 0 ) 37 depth in core (CM) at u > (0 -i * f I f I ec F ig u re 6 . M ajor c a t i o n t r e n d s ( c o n c e n tr a tio n i n sam ple v s . d e p th ) . C ore lTflOT B ottom w a te r c o n c e n tr a tio n s f o r t h i s c o r e : C at . Uo o /o o ; K, ,3 d o /o o j Mg, 1 .2 6 o /o o ; H a, 1 0 .5 0 o /o o (Em ery I9 6 0 ) 39 depth in core (CM) I* 1 0 •4 9 O -I 0 * Concentrations o f M ajor Cations ( % .) F ig u re 7 . M ajor c a tio n tre n d o ( c o n c e n tr a tio n i n sam ple v s . d e p th ) . Core 17811 Bottom w a te r c o n c e n tr a tio n s f o r t h i s c o re : Ca, . U O o /o o ; K, .3 8 o /o o ; Mg* 1 .2 6 o /o o ; Ka, 1 0 .6 1 o /o o (Emery I9 6 0 ) depth i n co re (CM) Concentrations of Major Cations ( % • ) 17811 Ca K Mg No 8.0 9.0 10.0 1.4 1.9 1.6 n > 9 .25 25 .45 .59 1 0 0 * 8 0 0 . 5 0 0 - F ig u re 6 . M ajor c a tio n tr e n d s ( c o n c e n tr a tio n i n sam ple v s . d e p th ) . Core 18U36 Bottom v a t e r c o n c e n tr a tio n s f o r t h i s c o re ; Cat .UO 0 / 0 0 ; K, .3 6 0/ 0 0 ; Mg, 1 .2 8 0 / 0 0 ; Na, 1 0 . 6l 0 /0 0 (finery i 9 6 0 ) U3 d ep th in co re (CM) o 2 2 09 * b* A PP Concentrations o f M ajor Cations (U Even a. c o r r e l a t i o n a n a l y s is b etw een Io n p a i r s r e v e a l s l i t t l e : no tw o s p e c ie s d i s p la y in g c o n s i s t e n t r e l a t i o n s h i p i n e i t h e r a d i r e c t o r I n d i r e c t s e n s e . When one exam ines th e u p p erm o st p o r ti o n s o f th e c o r e s , h o w ev er, a m ore c o n g ru e n t p a t t e r n em erg es. I t I s presu m ed t h a t th e tim e p e r io d o f I n i t i a l d e p o s itio n may b e t h e I n t e r v a l when r e a c t i o n s , i f th e y a r e g o in g t o o c c u r , commence. T h e r e f o r e , t h e " f i r s t " t r e n d may b e m ore I n d i c a t i v e o f th e t r u e i n t e r p l a y th a n th e o v e r a l l t r e n d , w hich can b e in f lu e n c e d by many v a r i a b l e s , su c h a s change o f c o m p o s itio n , an d p a r t i c u l a r l y f o r t h e s e c o r e s , v a r i a b l e r a t e s o f d e p o s itio n . The to p 50 cm o f f i v e c o re s e x h i b i t an i n c r e a s e i n t h e c o n c e n - +2 t r a t i o n o f Ca . T h is i n c r e a s e i s g e n e r a lly fo llo w e d b y a d e c r e a s e t o 100 cm. The same s i t u a t i o n was fo u n d b y S a y le s , a t a l . . (1973) i n t h e N o rth A t l a n t i c . F u rth e rm o re , f i v e o f t h e se v e n c o re s demon s t r a t e d e p le tio n o f K+ i n th e to p m e te r , w h ich i s a ls o s i m i l a r t o th e +2 f in d in g s o f S a y le s , e t a l . M g c o n c e n tr a tio n s v a r y a c c o r d a n tly w ith +2 Ca . As a g e n e r a l r u l e , t h e r e i s an i n i t i a l in c r e a s e fo llo w e d b y a d e c r e a s e , a lth o u g h n o t n e c e s s a r i l y i n t h e same c o r e s . B is c h o f f and S a y le s (1 9 7 2 ) a ls o fo u n d an I n i t i a l in c r e a s e I n some o f t h e c o r e s . +2 +2 The sodium io n c o n c e n tr a tio n b e h a v e s In o p p o s itio n t o Ca an d Mg , n o rm a lly d e c r e a s in g i n t h e to p 50 cm and th e n in c r e a s in g i n t h e n e x t 50 cm. C om parisons o f o th e r l e v e l s o f t h e c o re s do n o t m a n if e s t t h i s d e g re e o f s i m i l a r i t y o f t r e n d . S i l i c a 1 * 6 S i l i c a ( s i 02A<i^* l l k e th e maJ o r c a t i o n s , e x h i b i t s no p e r s is te n c y o f tr e n d w ith d e p th i n t o th e c o re (F ig s . 9-15)* I t i s t how ever, c h a r a c t e r i s t i c a l l y e n ric h e d o v e r norm al se a w a te r c o n c e n tr a tio n s . And, a s a ls o shown by th e c a tio n s , th e v a lu e s f o r s i l i c a a r e g e n e r a lly e r r a t i c w ith d ep th i n each o f th e c o r e s . A f i n a l an alo g y co n ce rn s th e to p m e te r o f th e c o r e s . As Vas +2 + +2 + t h e c a s e w i t h Ca , K , M g , a n d Na , s i l i c a d o e B s h o w a t r e n d I n t h i s r e g io n . B r i e f l y , i t in c r e a s e s i n th e f i r s t 90 cm and th e n de c r e a s e s . M easurem ents below th e u p p er m eter show no c o r r e l a t i o n s w ith in o r b etw een c o r e s . C h lo r in ity The s tr o n g e s t c o n s is te n c y in v o lv e s c h l o r i n i t y . Not o n ly do th e f i r s t 90 cm i n e ach c o re e x h i b i t a d e c r e a s e , b u t a l l th e way down th e c o re s s im i l a r b e h a v io r i s th e r u le (F ig s . 9 -1 9 )- C h lo r in ity i s a ls o c h a r a c t e r i s t i c a l l y above b o tto m w a te r v a lu e s a t th e to p s o f th e c o r e s , an d , l i k e th e o t h e r s , shows a c o n s id e ra b le number o f p e r tu r b a tio n s in p r o f i l e . Some o f th e s e anom alous v a lu e s may be d e s ig n a te d as a r t i f a c t s o f sam ple p r e p a r a tio n and tr e a tm e n t, b u t th e o v e r a l l c o in c id e n c e o f tr e n d s p r e c lu d e s m ajo r d is tu r b a n c e . Cl” g e n e r a lly in c r e a s e s w ith d ep th and h as an a v e ra g e v a lu e o f 19*36 o /o o . T h is i s s l i g h t l y h ig h e r th a n th e v a lu e o f b etw een 1 9 .0 9 - 19>19 o /o o r e p o r te d by Bnery ( i 96 0 ) f o r t h e b o tto m w a te r. F ig u re 9* S i l i c a , C h l o r i n i t y , and pH tr e n d s (v a lu e i n sam ple v s . d e p th in c o r e ) . Core 16991 B ottom v a t e r c h l o r i n i t y - 1 9 .0 5 o /o o (Emery I9 6 0 ) 48 16991 SIOs (ppm ) 10 19 2 0 Cl « .> 1 6 1 9 20 P H 7.0 8 0 100 200 3 0 0 F ig u re 10 . S i l i c a , C h lo r in ity and pH tr e n d s (v a lu e in sam ple v s . d e p th in c o r e ) . Core 1699U Bottom w a te r c h l o r i n i t y - 1 9 -U o /o o (Emery i 9 6 0 ) 1 * 9 50 SlOt (ppm ) 10 15 2 0 16994 c i o w 18 19 20 pH 7.5 8.0 100 a t a f 200 300 F ig u re 1 1 . S i l i c a , C h l o r i n i t y , an d pH tr e n d s (v a lu e i n sam ple v s . d e p th i n c o r e ) . C ore 16996 B ottom w a te r c h l o r i n i t y - 1 9 .1 1 o /o o (Em ery i 9 6 0 ) 51 52 16996 S IO i (ppm) 10 IS 2 0 C ISU ) 18 19 2 0 pH 7.8 8 .0 ! 1 0 0 200 9 0 0 F ig u re 1 2 . S i l i c a , C h l o r i n i t y , an d pH tr e n d s { v a lu e i n bam ple v s . d e p th in c o r e ) . Core 16997 B ottom w a te r c h l o r i n i t y - 1 9 -1 1 o /o o (Emery I9 6 0 ) 53 54 8 IO t (ppm) 1 0 1 5 20 16997 Cl f t.) 19 20 2 1 pH 7.0 8.0 1 0 0 200 500 F ig u re 13* S i l i c a , C h lo rin ity ' and pH tr e n d s (v a lu e in sam ple v s . d ep th i n c o r e ) . Core 17807 Bottom w a te r c h l o r i n i t y - 19*05 o /o o (Emery i 9 6 0 ) 55 56 17807 SfOt (ppm) 1 0 1 5 2 0 CI0U) 18 19 20 P H 7.5 8.0 IOO * ! ifl 200 I 500 F ig u re l b . S ilic a * C h lo r in ity and pH tr e n d s (v a lu e in sam ple v s . d e p th In c o r e }. Core 17811 Bottom w a te r c h l o r i n i t y - 1 9 .1 1 o /o o (Emery I9 6 0 ) 57 58 17811 SIOi (ppm) 1 0 1 5 2 0 Cl CX.) 19 2 0 2 1 pH 7.5 6 .0 a j a f t • s 1 0 0 200 5 0 0 F ig u re 15. S i l i c a , C h lo r in ity , and pH tr e n d s (v a lu e in sam ple v s . d e p th in c o r e ) . Core 18U36 Bottom v a t e r c h l o r i n i t y - 19*11 o /o o (Emery i 9 6 0 ) 59 60 18436 SlOa (ppm ) 10 15 2 0 CI0U) 18 19 20 pH 7.5 8 .0 1 0 0 200 9 0 0 61 PH A c id ity was th e m ost u n ifo rm p a ra m e te r m easu red . W ith r e s p e c t to d e p th and b etw een s t a t i o n s , th e c o re s d is p la y a hom o g en eity in pH w hich g r e a t l y ex ceed ed any o f th e o th e r v a r i a b l e s . As found by Emery ( I 9 6 0 ) , th e i n t e r s t i t i a l w a te r c h a r a c t e r i s t i c a l l y becom es more b a s ic w ith d e p th and i s u s u a lly b etw een a pH o f 7 .5 and 7 .6 a t th e sed in ten t • w a te r I n t e r f a c e ( F ig s . 9 - 1 5 ) . The h ig h e s t (m ost a l k a l i n e ) pH v a lu e s w ere from a san d y c o re ta k e n in th e s o u th e rn p o r tio n o f S a n ta C a ta lin a B a s in . The pH s u rp a s s e d 8 in p a r t s o f t h i s c o r e , w hich i s m ore t y p i c a l o f s u r f a c e w a te rs th a n b o tto m w a te r s . D is c u s s io n The m ost o u ts ta n d in g c h a r a c t e r i s t i c o f th e p o re w a te r c h e m is try d a ta i s i t s v a r i a b i l i t y . T h is c irc u m s ta n c e h a s b een o b se rv e d by o th e r w o rk e rs , e s p e c i a l l y in c o n t i n e n t a l m arg in a r e a s . M urray (1 9 7 3 ), H u lb e rt and G iven ( i n p r e p a r a t i o n ) , and F riedm an e t a l . , (1968) a r e among th o s e who h av e found n o tic e a b le v a r i a t i o n in th e p o re w a te r d a t a . The q u e s tio n o f c a u se m ust now be c o n s id e re d . Lack o f u n ifo r m ity Im p lie s t h a t i f c h e m ic a l r e a c t i o n s a re re sp o n s i b l e f o r th e p e r t u r b a t i o n s , t h e r e a r e many su ch r e a c t i o n s ta k in g p la c e w ith a w id e ra n g e i n r a t e s and e f f i c i e n c i e s . As can be o b se rv e d in F ig u re s 2 - 8 , f o r i n s t a n c e , i n some c a s e s d e p le tio n o c c u r s , in some no change i s r e c o r d e d , and i n s t i l l o th e r s e n ric h m e n t h a s o c c u rre d . T h is s ta te m e n t i s v a l i d f o r any o f th e v a r i a b l e s . R eview ing p o s s ib le s in k s and s o u rc e s f o r th e c a t i o n s , i t i s soon o b v io u s t h a t r e g a r d le s s o f th e io n o r t r e n d , e x p la n a tio n s f o r t h a t p a r t i c u l a r b e h a v io r e x i s t . 62 To w i t , A Ca+^ In c re a s e may be a t t r i b u t e d t o d is s o l u t i o n o f CaCO^ +2 ( S a y le s , e t a l • , 1973) w h ereas a Ca d e c re a s e may be cau sed by p r e c i p i t a t i o n o f CaC03 (B ro o k s, e t a l , , 1 9 6 8 ), be a r e s u l t o f a d s o rp tio n I n to o rg a n ic com plexes (M urray, 1 9 7 3 ), o r p e rh a p s a p ro d u c t o f a u th e g e n lc d o lo m ite fo rm a tio n (D re v e r, In p r e s s ) . K + I n c re a s e may be due to w e a th e rin g o f K -fe ld s p a rs ( S le v e r, e t a l , , 196S; M urray, 1 9 7 3 ), l l l l t e , o r montmor11l o n l t e c o n tr ib u tio n (B ls c h o ff and Ku, 1 9 7 0 ); a d e c re a se In th e abundance o f t h i s s p e c ie s may I n d ic a te e x tr a c tio n by l l l l t e and m o n tm o rillo n ite (B ls c h o ff and Ku, 1970; S a y le s , e t a l . , 1 9 7 3 ). M g+2 h as p o s s ib le s in k s in th e exchange c i t e s o f c la y s a f t e r rem oval o f a f e r r i c o x id e s h e a th ( S k o lk o v ltz , 1 9 7 2 ), by s u b s t i t u t i o n o f Mg+2 fo r Fe In th e i n t e r l a y e r s ( S le v e r , 1 9 7 1 ), o r by th e In s i t u p r e c i p i t a t i o n o f s e p l o l l t e o r c h l o r i t e (B lsc h o ff and S a y le s , 1972; B ls c h o ff and Ku, 1970 r e s p e c t i v e l y ) ; en rich m en t may r e s u l t when c h l o r i t e w e a th e rs ( A ll, e t a l . . 1 9 7 2 ). Sodium, g e n e r a lly c o n s id e re d u n r e a c tiv e , I s th e o n ly m ajo r c a tio n w hich h as n o t re c e iv e d e x te n s iv e c o n s id e r a tio n , R u s s e ll (1970) h as shown t h a t i t may re p la c e Ca on exchange s i t e s d u rin g H alm y ro ly sls and C lancy (1973) has found e v id e n c e f o r u p ta k e on exchange s i t e s o f f s o u th e rn C a lif o r n ia (1 9 7 3 ). T h is w ould acco u n t f o r s l i g h t d e p le tio n a lo n g w ith th e grow th o f a N a - b e l d e l l l te o r p h l l l l p s l t e , b o th o f w hich a r e t h e o r e t i c a l l y p o s s ib le (G a rre ls and M ackenzie, 1 9 6 6 ). S o u rces o f Na+ a r e more d i f f i c u l t to d e l i n e a t e . P la g io c la s s , w ith i t s w e ll known s u s c e p t i b i l i t y to w e a th e rin g ( e . g . , G o ld lc h , 1938) I s c e r t a i n l y a c a n d id a te , b u t th e l i s t m ust end h e re b ecau se c la y s c h a r a c t e r i s t i c a l l y d is p la y a p a u c ity o f sodium , and N a b e ld e lllte and p h l l l l p s l t e , i f p r e s e n t, a r e so m inor in abundance 63 t h a t th e y w ould be a n e g l i g i b l e f a c t o r i n t h i s r e g a rd . S i l i c a can a ls o b e in v o lv e d i n many p o s s ib le r e a c t i o n s . I t may b e r e le a s e d by th e d i s s o l u t i o n o f s i l i c i o u s b io g e n ic rem ain s su ch as d ia tc m s , r a d io - l a r i a n s , d i n o f l a g e l l a t e s , and sponge s p ic u le s (H e a th , in p r e s s ; W o lla s t, i n p r e s s ) o r r e le a s e d by many s i l i c a t e s d u rin g w e a th e rin g (M ackenzie, e t a l . . 1967)• I t may be rem oved by p r e c i p i t a t i o n o f a u th ig e n lc c l a y s , such a s was p o s tu la te d by G a r re ls and M ackenzie (1 9 6 6 ). T hese c l a y s , w hich In c lu d e s e p i o l i t e and p a l y g o r s k l t e , among o t h e r s , have b een i d e n t i f i e d a t g r e a t d e p th i n Deep S ea D r i ll i n g P r o je c t C ores (Bex and M urray, 1 9 7 0 ). S e p i o l i t e h as a ls o been fo u n d in la g o o n a l se d im en ts from H aw aii by B is tv e t e t a l . , (1 9 7 3 ). In summary, any o f th e above e x p la n a tio n s may be in v o k ed t o ac co u n t f o r a p a r t i c u l a r tr e n d o r segm ent o f an o v e r a l l t r e n d . Y et th e m y riad o f r e a c tio n s p o s s ib le f o r th e d e p le tio n o r e n ric h m e n t o f a d e s ig n a te d s p e c ie s w o u ld , i n m ost c a s e s , c a l l f o r a n ta g o n is tic r e a c t i o n s t o be o c c u rrin g w ith in and b etw een c o r e s . D e s p ite t h i s seem in g ly b le a k c irc u m s ta n c e , c o n s is te n c ie s a re p r e s e n t w hich le n d th e m se lv e s t o a n a ly s is . One i s th e s u s ta in e d K+ en rich m en t c o u p le d w ith i t s t y p i c a l d e c re a se in th e f i r s t m e te r. The l a t t e r phenomenon may b e due t o io n ex ch an g e, a lth o u g h C lancy (1 9 7 3 ), who w orked on th r e e o f th e c o re s from t h i s s tu d y , fo u n d no e v id e n c e t o s u b s t a n t i a t e t h i s p o s s i b i l i t y . T a b le IV d e m o n stra te s t h a t th e o b se rv e d f lu c tu a ti o n s in th e ra n g e o f p o re w a te r c o n c e n tra tIo n a co u ld b e encom passed by th e ran g e o f v a r i a t i o n i n exchange c a p a c i t i e s de te rm in e d by C lancy (1 9 7 3 ). F u r th e r , K + im placem ent was fo u n d t o ta k e p la c e e x te n s iv e ly d u rin g h a lm y ro ly s is by R u s s e ll (1 9 7 0 ), and S a y le s 6U TABLE IV Range In c a tio n abundance: exchange e i t e e v s . p o re w a te r Range i n C atio n Abundance SOURCE__________COM PONENT__________ Ms* 2__________ K*_____________ Ha* C lancy (1973) exchange aiteB .06% .09% >09% T h is study pore water .03% .02% .20% 65 e t & 1 . . ( 1973) s u g g e ste d r a p i d rem oval o f K + i n th e u pperm ost la y e r s o f se d im e n t. I t I s th e Judgem ent o f th e v r l t e r t h a t any o th e r e x p la n a t i o n w ould he l e s s f e a s i b l e and hence i t i s g iv e n as a t e n t a t i v e con c lu s io n . The o v e r a l l en ric h m e n t o f K* I s p ro b a b ly due t o th e d is s o lu t i o n o f K -fe ld s p a r. M urray (1973) b e lie v e d t h i s t o be a w o rk ab le h y p o th e s is , as d id th e s e v e r a l a u th o rs m en tio n ed a lre a d y i n t h i s a c o n te x t. +2 The i n i t i a l Ca in c r e a s e co u p led w ith th e su b se q u e n t d e c re a s e i s , as was s t a t e d , s im ila r t o th e s i t u a t i o n d is c o v e re d by S a y le s e t a l . , (1 9 7 3 ). T h e ir i n t e r p r e t a t i o n was a d i s s o l u t i o n o f CaCO^ fo llo w e d by +2 e n tra p m e n t o f Ca by g r e a t e r o rg a n ic c o n te n t. Inv o lv em en t o f o rg a n ic com plexes was p o s tu la te d b y M urray (1 9 7 3 ). How ever, th e d a ta i n t h i s I n v e s t i g a t i o n does n o t show a s te a d y d e p le tio n . I t i s b e lie v e d t h a t t h i s d e p a r tu r e may b e due to f lu c tu a ti o n s i n o th e r p a ra m e te rs w hich w i l l be d is c u s s e d l a t e r . +2 +2 W ith M g v a lu e s p a r a l l e l i n g Ca t o th e e x te n t t h a t 5 o f 7 c o re s show s im ila r b e h a v io r i n each c a s e , i t i s te m p tin g t o h y p o th e s iz e a lin k a g e b etw een th e tw o. C e r ta in ly some p e rc e n ta g e o f a l l n a tu r a l CaCO^ i s M gC0 3> I n f a c t , th e f ig u r e may ap p ro ach 30# (D re v e r, in p r e s s ) . The amount i s p ro b a b ly l e s s th a n 5# i n th e s e s e d im e n ts , how e v e r , and t h i s q u a n tity w ould be masked in th e d if f e r e n c e i n a b s o lu te +2 v a lu e s — M g b e in g ro u g h ly th r e e tim e s more p r e v a le n t. D egree o f a c i d i t y a ls o p o in ts t o s e g re g a tio n o f th e s e c a t i o n s . A brupt ch an - +2 g e t In pH a re f r e q u e n tly m irro re d by th e Ca c o n c e n tr a tio n ; a +2 h a p p e n sta n c e n o t d em o n stra te d by th e r e l a t i v e c o n c e n tr a tio n o f M g . So w hat co u ld e x p la in th e p r o f i l e s in th e to p s o f th e c o re s? And, 66 i f th e g e n e r a l te n d e n c y o f t h e c o l l e c t i v e p r o f i l e * to w a rd d e p l e t i o n i s r e a l , w hat c o u ld a c c o u n t f o r t h i e f Em ploying th e d a ta o f C lan cy ( 1 9 7 3 ), t h e se co n d q u e s tio n may b e a t l e a s t p a r t i a l l y a n sw e re d . Com p a r in g t h e ra n g e o f e x c h a n g e a b le m agnesium from th e C lancy s tu d y t o th e ra n g e in p o re w a te r s i n t h i s s tu d y (T a b le IV ), th e e n t i r e v a r i a t i o n i n t h e p o re w a te r s l i p s n e a t l y i n t o p l a c e . I n o th e r w o rd s, any +2 M g d e p le tio n may b e q u i t e a d e q u a te ly a c c o u n te d f o r on th e ex ch an g e s i t e s . The e n ig m a tic i n i t i a l e n ric h m e n t s t i l l r e q u i r e s e x p la n a tio n even th o u g h th e in c r e a s e i s , in e a c h c a s e , a s l i g h t o n e . C h lo ro p h y ll i s c o n v e rte d to th e g re e n p ig m en t p h e o p h y tin r a p i d l y a f t e r d e p o s it i o n , +2 and t h i s change in v o lv e s a r e l e a s e o f Mg Y et t h i s I n c r e a s e i s m ost p r e v a le n t in re d u c in g s e d im e n ts , and ev en i n t h a t en v iro n m e n t c o u ld o n ly a c c o u n t f o r a few p a r t s p e r m i l l i o n . O th e r o rg a n ic com plexes may be in v o lv e d , a s M g -ad ip o cere (M u rray , 1 9 7 3 ), b u t a s i m i l a r a r gum ent w ould a p p ly h e r e a s f o r th e p ig m e n ts. The l a s t p o s s i b i l i t y may b e t h e w e a th e rin g o f a m p h lb o le . A l th o u g h Mg may b e r e l e a s e d b y t h i s m in e r a l, i t i s q u a n t i t a t i v e l y unimr- p o r te n t i n t h e b o r d e r la n d ( F l e i s c h e r , 1970) and h e n c e may a l s o b e r u le d o u t. F i n a l l y , i t i s p o s s i b l e t h a t th e exch an g e s ite -M g r e l a t i o n s h i p i s an e p h em eral o n e , and Mg may b e g iv e n up as w e ll as rem oved, depen d in g on o th e r f a c t o r s t o b e d is c u s s e d l a t e r . O u ts id e o f th e p o s s i b i l i t y o f s h e a r c o in c id e n c e o f p e r t u r b a t i o n and a n a l y t i c a l e r r o r , no o th e r e x p la n a tio n s seem J u s t i f i a b l e . The e n ric h m e n t i s , t h e r e f o r e , u n a c c o u n te d f o r . 67 The p a t t e r n o f Na+ In th e u p p e r m e te r l a lik e w is e e n ig m a tic . The d e p le tio n fo llo w e d by e n ric h m e n t may b e due t o I n i t i a l u p ta k e o f Na+ by c l a y s , y e t I f t h i s w ere th e s o le e x p la n a tio n , t h i s w ould n e c e s s i t a t e a s u b se q u e n t r e l e a s e , w hich I s n o t a p ro b a b le c irc u m s ta n c e In th e o p in io n o f t h i s i n v e s t i g a t o r . H ow ever, th e e f f e c t o f p l& g lo cl& se d i s s o l u t i o n may be su p erim p o se d on th e ex ch an g e s i t e e f f e c t . F l e i s c h e r (1970) h a s shown t h a t p la g l o c l a s e i s ab u n d an t In th e b o r d e rla n d so t h a t a c o n t r ib u t i o n o f th e io n I n q u e s tio n I s c e r t a i n l y w ith in th e re a lm o f c r e d i b i l i t y . In a d d i t i o n , C lancy (1973) h a s shown t h a t c la y s a r e a c c u m u la tin g Na+ on t h e i r exchange s i t e s In m inor b u t o b s e rv a b le q u a n t i t i e s . I t I s c o n c e iv a b le , t h e r e f o r e , t h a t I n t e r p l a y b etw een th e two m echanism s i s o c c u r r in g , w ith l o s s to ex ch an g e s i t e s b e in g dom i n a n t. The f a c t t h a t sodium v a lu e s te n d t o be s l i g h t l y lo w e r i n th e i n t e r s t i t i a l w a te r th a n i n th e b o tto m w a te r g iv e s c re d e n c e to th e c h o ic e o f dom inant m echanism . The u b iq u ito u s e n ric h m e n t o f s i l i c a In th e p o re w a te r s In con ju n c t i o n w ith th e I n i t i a l I n c r e a s e fo llo w e d by a d e c r e a s e i s a s i t u a t i o n s i m i l a r to t h a t o b se rv e d by B is c h o ff and S a y le s (1 9 7 2 ). They con s tr u e d t h i s a s an i n d i c a t i o n o f i n i t i a l d i s s o l u t i o n o f s i l i c e o u s b i o g e n ic rem ain s fo llo w e d by a s h e a th in g o r c o a tin g o f th o s e t e s t s w ith an a u th ig e n ic c l a y , p o s s ib ly s e p i o l i t e . T h is th e o r y i s d i f f i c u l t to g e s t b u t i t I s su rm ize d t h a t th e e r r a t i c n a tu r e o f th e p r o f i l e s In t h i s s tu d y w ould c lo u d t h e d e t e c t i o n o f su ch r e a c t i o n s . I f th e y a r e ta k in g p l a c e , th e n t h e i r im p act may be ln d l s c e m a b l e in th e s c a t t e r . B ecause a l l i n v e s t i g a t o r s who m easured s i l i c a found an I n c r e a s e In c o n c e n tr a tio n r e l a t i v e to b o tto m w a te r , i t i s b e lie v e d d i s s o l u t i o n i s 60 ta k in g p la c e . M ackenzie, e t a l . , (1967) d e m o n stra te d how c la y s r e s pond t o se a w a te r u n d e r s a tu r a te d w ith r e s p e c t t o s i l i c a . T h e ir f i n a l s o lu tio n s a c h ie v e d c o n c e n tr a tio n s harm onious t o th o s e o b se rv e d in t h i s s tu d y . E x am in atio n o f sm ear m ounts r e v e a ls th e p re s e n c e o f r a d i o l a r l a n s and sponge s p ic u l e s . D iatom s and D i n a f l a g e l l i t e s , a l th ough u n se e n , a re c e r t a i n l y p r e s e n t as w e ll (Em ery, I9 6 0 ). One may choose betw een b io g e n ic and te r r ig e n o u s s o u rc e s t o r e s o lv e th e q u e ry : e i t h e r one o r b o th may be o p e ra tiv e * A h y p o th e s is t o a cc o u n t f o r th e re m a rk a b le r e p l i c a t i o n o b se rv e d i n th e c h l o r i n i t y p r o f i l e s may n o t b e w a rra n te d - - a t l e a s t one b a se d on t h i s w ork. I n d iv id u a l d e f le c tio n s from th e norm may be d ism is se d as sam ple c o n ta m in a tio n ( e . g . , d i l u t i o n o r e v a p o ra tio n ) b u t th e p e r s is te n c y o f p r o f i l e shape betw een c o r e s , r e g a r d le s s o f th e a b s o lu te v a lu e s , i s to o s t r i k i n g t o be c o in c id e n c e . P h o s p h o r ite , w hich i s ab undant i n th e b o rd e rla n d sed im e n ts ( Emery, I9 6 0 ; P a sh o , 1 9 7 3 ), i s th e o n ly known s o l i d i n th o s e sed im e n ts t h a t c o u ld r e a c t w ith Cl , b u t th e q u a n t i t a t i v e a s p e c t i s unknown. D ig e s tin g th e d is c u s s io n o f S ie v e r (1 9 6 5 ), th e l i k e l i h o o d o f r e s id u a l c h l o r i n i t y valueB and th e in flu e n c e o f v a r io u s p h y s ic a l f a c t o r s m ust be c o n s id e re d . I f s e d im e n ta tio n r a t e i s h ig h enough to o u td is ta n c e th e upw ard f lu x o f Cl” , th e n M P a l e o c h l o r in i t i e s " may b e p re s e rv e d . I f c la y s can a c t as m em branes, and I f th e sed im en t i s h e te ro g e n e o u s , and i f p e r m e a b ility v a r i e s , th e n c h l o r i n i t y v a lu e s may change s i g n i f i c a n t l y a t d i f f e r e n t l e v e l s i n th e c o r e s . Even th o u g h th e l i s t o f p ro v is o s i s fo rm id a b le , none a re u n re a s o n a b le . For exam p l e , K u llen b e rg ( 195*0 h as d e te rm in e d a d if f u s io n c o e f f i c i e n t o f 69 2 x 1<T6 cm2 /s e c f o r C l" , Based on t h i s e x p e rim e n ta lly d e rlv a d v alu e* he c a lc u la te d t h a t fo r a e d ln e n ta tlo n r a t e s In th e B a ltic Sea o r i g i n a l c h l o r i n i t y c o n c e n tr a tio n w ould n o t be o b acu red f o r p e rh a p s a few th o u san d y e a r s . T hus, " p a l e o s a l l n l t l e s " can be p r e s e r v e d , e s p e c i a l l y in a r e a s w ith h ig h r a t e s o f d e p o s itio n . S le v e r , e t _ a l . , (1965) n o te s th e work o f M ckelvey and M ilne (1960) who d e m o n stra te d t h a t when s a l t w a te r i s fo rc e d th ro u g h m o n tm o rlllo n ite a t h ig h p r e s s u r e , f r e s h e r w a te r i s e f f u s e d . So lo c a l In c re a s e s In c h l o r i n i t y a r e p o s s ib le w ith a g e n e ra l In c re a s e o f Cl~ c o n c e n tr a tio n w ith I n c r e a s in g p r e s s u r e (d e p th In se d im e n t) p r e d ic te d . A d d re ssin g o u rs e lv e s to th e f i n a l p a i r o f p r o v is io n s , Emery (1960) a lo n g w ith many o th e r i n v e s t i g a t o r s have shown b o rd e rla n d sed im e n ts encom pass a b ro a d gamut o f s i z e s , s h a p e s , c o m p o s itio n s , and o th e r p a ra m e te rs . So th e s e l a s t two c r i t e r i a seem to be f u l f i l l e d . C h lo r in ity v a r i a t io n s a r e n o t u n iq u e to t h i s s tu d y . E r r a t i c pore w a te r c h l o r l n i t l e s have been re p o rte d by s e v e r a l a u th o r s . S le v e r e t a l . , (1 9 6 1 ), found a v a r i a t i o n o f n e a r ly 2 o /o o in t h e i r c h l o r i n i t y d a ta from one c o re and a t t r i b u t e d t h i s to e i t h e r membrane o r p a l e o s a l i n i t y e f f e c t s . F riedm an, e t a l . . (1968) found low er c h l o r i n i t y v a lu e s in th e san d s o f th e in n e r s h e lf th a n th e s i l t s o f th e o u te r s h e l f . They co n clu d ed t h a t an I n f lu x o f f r e s h w a te r n e a r sh o re o r a membrane e f f e c t co u ld e x p la in t h i s d is c re p a n c y . A ll a t a l . (1972) found a v a r i a t i o n o f more th a n 1 o /o o i n B a ffin Bay s e d im e n ts . F in a lly B la c h o ff and S a y le s (1972) found u n e x p la in a b le p e r tu r b a tio n s in t h e i r p o re w a te r c h l o r l n i t l e s . A d d itio n a lly , th e y o b serv e d t h a t t h e i r v a lu e s in c re a s e d w ith sed im en t d ep th by ab o u t 0 .0 o /o o . The f in d in g ! o f p re v io u s I n v e s tig a to r * p lu s th e f e a s i b i l i t y o f t h e v a r io u s e x p la n a tio n s s u g g e ste d above le a d s t h i s w r i t e r t o con c lu d e t h a t c e r t a i n p h y s ic a l f a c t o r s may in d e e d I n flu e n c e c h l o r i n i t y v a lu e s . The o th e r io n s may be in flu e n c e d s b v e i l , w hich may s e rv e as an e x p la n a tio n f o r th e e r r a t i c p r o f i l e s o b s e rv e d . A f te r a s s e s s m ent o f o th e r f a c t o r s , t h i s d is c u s s io n w i l l be c o n tin u e d . BULK CHEMISTRY O xides Elements analyzed in the solid phase vere the same as those measured in the pore waters. SiOg, MgO, CaQ, KgO, and Na^O were studied. Al^O^ content waB also determined because of its importance in clay minerals. CaO was i n t e r p r e t e d a p a r t from th e o th e r s b ec au se o f i t s in tim a te a s s o c ia tio n w ith th e b io g e n ic com ponent. O th er s tu d ie s o f th e B o rd er la n d ( e .g . P re n sk y , 1973; C lan cy , 1973) h av e shown t h a t CaCO^ can ex ceed 20 - 25Jt o f th e d ry sed im en t w e ig h t. B ecause o f t h i s , th e CaO d a ta i s d is c u s s e d below r a t h e r th a n b e in g p r e s e n te d w ith th e r e s t o f th e I n o rg a n ic c o n s ti t u e n t s . The th r e e b a s in s a re g e n e r a lly con s i s t e n t w ith in th e m se lv e s w ith r e s p e c t t o CaO. D iffe re n c e s w hich do e x i s t can be a s s ig n e d t o d i s s i m i l a r s e d im e n ta tio n r a t e s and c o n tr o l by s e a l e v e l changes and r e l a t e d phenomena (G o rs lln e e t a l . , 1 9 6 9 ). The d a ta was a n a ly z e d on a c a rb o n a te f r e e b a s i s . I t im m ed iately became a p p a re n t t h a t co m p en satio n m ust b e made f o r o th e r f a c t o r s . F le is c h e r (1970) a s c e r ta in e d t h a t 15-30Jf o f th e sed im en t was composed o f n o n -c la y m in e r a ls . The m ost dom inant n o n -c la y m in e ra l was q u a r tz , w hich n o t o n ly can d i s t o r t th e SiOg p e rc e n ta g e s lin k e d w ith c l a y s , b u t whose v a ry in g p r o p o r tio n s c o u ld g r e a t l y in f lu e n c e th e tr e n d s o f o th e r o x id e s . A ls o , p la g l o c l a s e , K - fe ld s p a r, and a m p h lb o le, th e o th e r th r e e n o n -c la y m in e ra ls p r e s e n t i n a p p r e c ia b le am o u ts, w ere Judged 71 r e le v a n t I n t h a t th e y can g r e a t l y e f f e c t th e v a lu e s o f th e m ajo r c a t i o n s . C lay m in e ra l In v o lv em en t I n d ia g e n e s is b e in g a p rim e o b je c t i v e o f t h i s i n v e s t i g a t i o n , th e o x id e s w ere r e c a lc u la te d on a non c la y - m in e r a l- f r e e b a s i s , such t h a t th e d a ta employed f o r I n t e r p r e t a t i o n was f r e e o f th e e f f e c t s o f CaCO^ and n o n -c la y m in e ra ls . The r e l a t i v e abundance o f th e oxideB i s shown i n F ig u re s 1 6 -2 2 . The ra n g e o f abundance o f th e n o n -c la y s (a llo w in g f o r th e p o t e n t i a l d if f e r e n c e i n t h e i r am ounts) i s r e p r e s e n te d by th e w id th o f th e sw a th e. The r e a d e r sh o u ld b e a r i n mind t h a t th e v a lu e s p l o t t e d a re much h ig h e r th a n norm al b e c a u se o f th e a d ju stm e n ts made. I t f u r t h e r s h o u ld be n o te d t h a t th e sandy c o re ( I 8U36) , and c o n c e iv a b ly i s o l a t e d sam ples from o th e r c o r e s , may s u rp a s s th e ap p ro x im a te l i m i t s in n o n -c la y m in e ra ls fo u n d by F le is c h e r (1 9 7 0 ). SIO^ and Al^O^, th e c h ie f com ponents, o f te n d e m o n stra te a r a t h e r sy m m e tric a l b e h a v io r i n t h e i r p r o f i l e s . N e ith e r m a n ife s t a c o n s is t e n t t r e n d , h o w ev er, and th e a b s o lu te v a lu e s a re w ith in norm al l i m i t s c o n s id e rin g th e assum ed co m b in atio n o f m in e ra ls u sed i n th e compen s a t i n g . M gO does show a t r e n d . E x c lu d in g th e sandy c o r e , w ith i t s unknown q u a n tity o f n o n - c la y s , MgO p e r c e n t d e c re a s e s down th e c o re in 5 o f 6 p r o f i l e s . A d e c re a s e fo llo w e d by an in c r e a s e i s a ls o a p p a re n tly p r e s e n t i n th e to p m e te r. I t s h o u ld be m en tio n ed t h a t o b se rv e d tr e n d s a r e b a s e d on th e mean v a lu e s o f MgO, and u s in g th e ex trem e v a lu e s o f th e assum ed v a r i a t io n s i n th e n o n -c la y m in e ra ls th e p e rc e n ta g e s c o u ld a l t e r enough t o d r a s t i c a l l y change th e s lo p e s o f th e l i n e s a lth o u g h n o t n e c e s s a r ily th e tr e n d s . D ata p r e s e n te d b y Grim e t a l . ( 19^0 ) , Figiore 1 6 . T rends i n O xides (p e rc e n ta g e s v s . d e p th in c o re ) C o re; 16991 W idth o f Bv&the r e p r e s e n ts norm al ra n g e fo r th e d i f f e r e n t o x id e s in th e c la y m in e r a ls , assum ing f i n i t e ran g e in abundance o f o th e r c o n s titu e n ts ( F le i s c h e r , 1970) 73 « ft* e u a 4 3 «* & 100 o 200 9 0 0 SiOt 6 0 65 -* j . Chemical Analysis ( w t. % ) 16991 ALsOs MgO KzO NotO * F ig u re 17. T rends in O xides (p e rc e n ta g e s v s . d e p th i n c o re ) C o re: 1699U W idth o f sw athe r e p r e s e n ts norm al ran g e fo r th e d i f f e r e n t o x id e s in th e c la y m in e r a ls , assum ing f i n i t e ran g e i n abundance o f o th e r c o n s titu e n ts ( F le i s c h e r , 1970) 75 Chemical Analysis ( w t.% ) 16994 ALtOs MgO KtO NotO F ig u re 18 . T rends i n O xides (p e rc e n ta g e s v s . d e p th In c o re ) C o re; 16996 W idth o f sw athe r e p r e s e n ts norm al ran g e f o r th e d i f f e r e n t o x id e s in th e c la y m in e r a ls , assum ing f i n i t e ra n g e i n abundance o f o th e r m in e ra ls ( F le i s c h e r , 1970) 77 StOc 55 60 S e « 5 | a «* I too. £00. 500. Chemical Analysis ( w t.% ) 16996 ALcOy 3 0 MgO KtO NotO 1 % F ig u re 19* T rends In O xides (p e rc e n ta g e s v s . d e p th in c o re ) C o re: 16997 W idth o f s v a th e r e p r e s e n ts norm al ran g e f o r th e d i f f e r e n t o x id e s I n th e c la y m in e r a ls , assu m in g f i n i t e ra n g e i n abundance o f o th e r c o n s ti t u e n t s ( F le i s c h e r , 1970) 79 SiOt 6 0 65 • •_ 300. CEsemical Analysis (w t.% ) 1 6997 ALtO» 25 MgO 6 7 8 G O a> F ig u re 20. T rends in O xides (p e rc e n ta g e s v s . d e p th in c o re ) C ore; 17607 W idth o f sw athe r e p r e s e n ts norm al ra n g e f o r th e d i f f e r e n t o x id e s i n th e c la y m in e r a ls , assum ing f i n i t e ra n g e i n abundance o f o th e r c o n s titu e n ts ( F le i s c h e r , 1970) 01 s e e a i & SiOt 6 0 69 100 200 900 m m m Chetmlcal A oalysii ( w t.% ) 17807 ALcOs MgO KtO NosO F ig u re 21. T rends In O xides (p e rc e n ta g e s v s . d e p th In c o re ) C ore: 1 7 8 1 1 W idth o f sw athe r e p r e s e n ts norm al ran g e f o r th e d i f f e r e n t o x id e s In th e c la y m in e r a ls , assu m in g f i n i t e ra n g e i n abundance o f o th e r c o n s ti t u e n t s ( F le i s c h e r , 1970) 83 SiOt 60 65 5 19 < 8 6 * 2 o « 100. i 200. 30 0 Chemical Analysis ( w t.% ) 17811 ALtOt MgO KtO NotO F ig u re 2 2 . T rends In O xides (p e rc e n ta g e s v s . d e p th i n c o re ) C ore: l6*t36 W idth o f s v a th e r e p r e s e n ts norm al ran g e f o r th e d i f f e r e n t o x id e s i n th e c la y m in e r a ls , assum ing f i n i t e ra n g e i n abundance o f o th e r c o n s titu e n ts ( F le i s c h e r , 1970) 85 depth l a core (CM) Cheaiical Analysis ( w t.% ) 18436 SiOt ALfOs MgO KtO NotO 69 70 100 200 300 D rev er (1971)* and P a r k e r (1 9 7 3 )» v e r e s i m i l a r in a b s o lu te MgO p e rc e n ta g e t o t h i s stu d y * Of a l l t h e v e r t i c a l p r o f i l e s I n t h i s s tu d y , none a r e m ore c o n s is t e n t th a n th o s e f o r KgO ( F ig s . 1 6 - 2 2 ). I n a l l 7 c o re s KgO I n c r e a s e s w ith d e p th . And, b e c a u s e o f th e m in u te q u a n t i t i e s o f K - f e ld s p a r In th e s e d im e n t, th e o p p o r tu n ity to d e v ia te from t h e mean v a lu e s I s s m a ll in d e e d . A verage u n c o r r e c te d KgO v a lu e s d e te rm in e d I n t h i s v o rk c l u s t e r aro u n d 1 .5Jf. T h is i s th e Bame ra n g e o f D rev er* s (1 9 7 1 ) d a ta b u t lo w e r th a n th e p e r c e n ta g e s r e p o r te d by Grim e t a l . (1 9 ^ 9 ) and P a rk e r (1 9 7 3 ). Na^O v a lu e s g e n e r a lly e x h i b i t no p r e f e r e n c e to w a rd i n c r e a s i n g o r d e c r e a s in g w ith d e p th . W ith r e g a r d t o a b s o lu te v a lu e B , t h e q u a n t i t i e s r e p o r te d by Grim e t a l . (1 9 ^9 ) an d D re v e r (1 9 7 1 ) w ere lo w e r th a n th o s e o f t h i s s tu d y , w hich i n t u r n a re s l i g h t l y l e s s th a n th e v a lu e s p u b lis h e d by P a rk e r (1 9 7 3 ). Amorphous S i l i c a The p e rc e n ta g e am orphous SiOg ( c h i e f l y b io g e n ic s i l i c a ) i n t h e t h r e e c o re s s tu d i e d (o n e from each b a s in ) te n d e d t o d e c r e a s e i n th e San N ic o la s and S a n ta C a ta lin a c o re s an d re m a in unchanged In th e S a n ta C ruz c o r e . F ig u re 23 shows t h i s a lo n g w ith th e o b v io u s d i f f e r e n c e b etw een b a s i n s . N am ely, th e am orphous s i l i c a c o n te n t I n th e S a n ta C ruz B a sin s e d im e n ts ( 1699k) i s n o tic e a b ly h ig h e r th a n t h e o t h e r tw o , b e in g above 1% th ro u g h o u t th e c o re as o p p o sed t o v a lu e s o f 1$ f o r t h e o t h e r s . F ig u re 2 3 . Amorphous S i l i c a A bundance v s . d e p th in c o r e . Numbers d e s ig n a te San N ic o la s , S a n ta C ru z , and S a n ta C a ta lin a B a s in s , r e s p e c t i v e l y . 88 0 100 eoo 900. Amorphous Silica ( % ) 16991 16994 16996 Amorphous A lu m ln o s illc a te s 90 The amount o f amorphous A l - s i l i c a t e s v a s com puted on th e b a s is o f a one t o one r a t i o (SiOg : A l^O ^). T h is r a t i o was chosen a r b i t r a r i l y . b u t seem s t o b e r e p r e s e n t a t i v e b a se d upon a re v ie w o f th e l i t e r a t u r e ( e . g . , F o l l e t e t a l . . 19^5; W eaver and P o l l a r d , 19T 3). A n aly ses w ere made on th e same th r e e c o re s as ab o v e. V ote t h a t i n a l l coreB (F ig . 2k) th e I n i t i a l p e rc e n ta g e i s th e same b u t from t h a t p o in t th e San N ic o la s B a sin Core (16991) end th e S a n ta C a ta lin a B asin c o re (16996) e x h ib it more amorphous A l - s i l i c a t e w ith d e p th w h ereas th e S a n ta Cruz c o re shows no i n c l i n a t i o n to w ard e i t h e r d i r e c t i o n . S t r u c t u r a l Iro n and " F re e Iro n " The same th r e e c o re s w ere a n a ly z e d f o r " n a n - fr e e " ir o n (e x p re s s e d a s Fe^O^) and " f r e e " i r o n ( d i t h i o n l t e s o lu b le f e r r i c o x id e ) , th e fo rm er b e in g th e d if f e r e n c e betw een t o t a l and " f r e e " ir o n . F ig u re s 2^ and 26 show th e r e l a t i o n s h i p o f e ach v a r ia b le w ith d ep th i n th e c o re . D isc o u n tin g th e a b e r r a n t v a lu e a t th e b o tto m o f th e S a n ta C a ta lin a B a sin Core ( 16996) " n o n -fre e " ir o n ra n g e s from a b o u t U t o 6% and d is p la y s no p r e f e r e d tr e n d . C oncom itant w ith t h i s b e h a v io r , " f r e e " ir o n in c r e a s e s i n th e San N ic o la s Core (16991) and th e S a n ta Cruz Core (1699*0 b u t d e c re a s e s i n th e C a ta lin a C ore. H ie a b s o lu te v a lu e s ra n g e from ab o u t 0.75-l*5Jf« F ig u re 2k. Amorphous alu m ln o s i l l c a te Abundance v s . d e p th i n c o re . Humbers d e s ig n a te San N ic o la s , S a n ta C ru z, and S a n ta C a ta lin a B a s in s , r e s p e c t i v e l y . 91 depth I n core (cm) Amorphous A huninosilicates ( % ) 16991 16994 16996 100. 3 0 0 . vc to F ig u re 2 5 . S t r u c t u r a l I r o n ( n o n - f r e e i r o n ) p e rc e n ta g e v e . d e p th i n c o r e . V alue o b ta in e d b y s u b t r a c t i n g " f r e e " i r o n from t o t a l i r o n . 93 s v M4 O X w ♦* & 100 200. 300 STRUCTURAL IRON R) 16991 16994 16996 V 0 A F ig u re 2 6 . " F r e e - I r o n " A bundance v s . d e p th in c o r e . Numbers d e s ig n a te San N ic o la B , S a n ta C ru z , and S a n ta C a ta lin a B a s in , r e s p e c t i v e l y . 95 depth In core (CM) M o o o o — 0> 10 £ 10 (0 _ o" < 0 O ft 96 Free Iron” (Fe208) 97 D is c u s s Io n The common d e c r e a s e o f th e MgO p e r c e n ta g e s and p a r t i c u l a r l y th e c o n s i s t e n t a u g m e n ta tio n o f K2O p e r c e n ta g e s w ith d e p th w ould seem to have d i r e c t b e a r in g on th e p ro b lem o f d l a g e n e s l s . C o n s id e rin g th e s e d a ta a lo n e , h o w ev er, can o n ly b e g e t s p e c u la tio n * I t s u f f i c e s t o sa y t h i s t h a t th e s e tr e n d s a r e a f f e c t e d by ch an g es i n m in e ra lo g y , a s s p e c ie s and r e l a t i v e ab u n d an ce c h a n g e , and by c o m p o s itio n a l ch an g es w ith in th e m in e r a ls th e m s e lv e s . In l i g h t o f th e s e f a c t s a co m p le te d is c u s s io n o f th e o x id e s w i l l b e w aived a t t h i s tim e in f a v o r o f p r e s e n tin g an a n a l y s is a f t e r th e co m p le te s u i t e o f d a ta h av e b een p r e s e n te d . Smear m ounts h av e shown an abun d an ce o f sponge s p ic u l e s i n th e se d im en t sam p les o f t h i s s tu d y . R a d lo la r la n s h av e a ls o b een o b s e rv e d , and d ia to m s and d i n o f l a g e l l a t e s a re m ost c e r t a i n l y p r e s e n t (Em ery, 1 9 6 0 ). T hese o rg a n ism s a r e c h a r a c t e r i s t i c a l l y com posed o f p o o rly c r y s t a l l i z e d SIO2 and I t i s b e lie v e d t h a t th e s l i g h t l y d e c r e a s in g am orphous s i l i c a c o n te n t r e f l e c t s t o some e x te n t th e p re s e n c e o f th e s e o rg a n is m s . Some o f th e am orphous s i l i c a i s n eed ed to m atch th e am ount o f A I2O3 found by th e Na2C03 le a c h . T h u s, b o rro w in g s i l i c a to a c h ie v e an assum ed fo rm u la o f A l2< > 3 . S i0 2 d e p le te s th e am ount o f amorpho*- t S i0 2 w hich c o u ld come from th e b i o t a . I t i s a p p a re n t ( F ig s . 23 and 24) from th e v i s a v i s r e l a t i o n s h i p o f th e p r o f i l e s t h a t I n San N ic o la s and S a n ta C ruz B a s in s th e amount o f am orphous A l - s l l l c a t e I n c r e a s e s and th e b io g e n ic s i l i c a d e c r e a s e s . In S a n ta C ruz b a s in b o th rem ain c o n s ta n t w ith r e s p e c t t o d e p th i n th e c o r e . B oth o f th e s e phenom ena may b e e x p la in e d by In v o k in g th e r e c e n t 98 h i s t o r y o f th e b o r d e rla n d . S p e c i f i c a l l y , finery (i9 6 0 ) and G o rs lln e e t a l . (1969) have shown t h a t s e d im e n ta tio n r a t e s w ere much h ig h e r d u rin g th e l a s t low s ta n d o f se a l e v e l (a b o u t 8000 B .P .) . U nder th e s e c o n d itio n s a g r e a t e r q u a n tity o f la n d - d e riv e d am orphous a lu m in o - s i l i c a t e s w ould b e e n te r in g th e b a s in s : n o t o n ly b e c a u se o f t h e i r p ro x im ity t o s o u rc e s o f r u n o f f , w here d e e p e r s o i l zones (zone o f de p o s it i o n ) may be e ro d e d , b u t a ls o b e c a u se d u rin g an a lle g e d p l u v i a l p e r io d ch em ical w e a th e rin g may have b een more in te n s e p ro d u c in g more amorphous m a te r ia l r e l a t i v e t o th e p r e s e n t. F u rth e rm o re , th e " b io lo gical** s e d im e n ta tio n r a t e p ro b a b ly d id n o t change t o a la r g e d e g re e (P re n sk y , 1 9 7 3 ), b u t b e c a u se o f th e in c r e a s e d i n f l u x o f te r r ig e n o u s sed im e n ts th e fo rm er w ould have b een d i l u t e d — th u s show ing an a p p a re n t d e c re a s e . As s e d im e n ta tio n r a t e g r a d u a lly d e c re a s e d so d id th e amor phous a lu m ln o s illc a te p e r c e n ta g e , w ith th e r e l a t i v e l y u n d ilu te d b io g e n ic s i l i c a a p p e a rin g t o became more d o m in an t. The c o n s ta n t r e l a ti o n s h ip betw een th e two ty p e s o f amorphous m a te r ia l i n S a n ta Cruz B asin i s r e l a t e d t o t h a t b a sin * b a b s o lu te r a t e o f d e p o s itio n , finery ( i 9 6 0 ) r e p o rte d t h a t t h i s b a s in r e c e iv e s more sed im en t p e r u n i t o f tim e th a n do th e o t h e r s , and th e s p e c i f i c lo c a tio n o f t h i s c o re i s J u s t o f f th e edge o f a subm arine f a n . Com parable d e p th s i n th e v a r i ous c o re s a re n o t t h e r e f o r e is o c h ro n o u s , and th e f u l l e x te n t o f th e S a n ta Cruz c o re p ro b a b ly I s c o r r e l a t i v e w ith o n ly th e to p p a r t s o f th e San N ic o la s and C a ta lin a c o r e s . I t i s p r e d ic a te d t h a t a t e q u iv a l e n t tim e p la n e s th e same e f f e c t w ould b e m a n ife s t on a l l th e c o r e s . U pw elllng and h ig h p r o d u c tiv ity a r e a ls o a c h a r a c t e r i s t i c o f t h i s a r e a (D avid E. D rake, p e r s o n a l com m unication) and t h i s c o u ld th e a p p a re n t enigm a o f th o s e sed im e n ts h a v in g h ig h e r a b s o lu te am ounts o f amorphous s i l i c a . V e r t i c a l d i s t r i b u t i o n o f th e two ty p e s o f ir o n o x id e s tu d ie d h a s a d i r e c t b e a r in g on m odels o f m agnesium rem o v al. The im p lic a tio n o f th e d a ta g e n e ra te d i n t h i s s tu d y w ith r e g a rd t o th o s e m odels i s d is c u s s e d in a l a t e r s e c tio n . MINERALOGY N on-Clay M in erals Q uartz* p la g i o c l a s e , K -fe ld s p a r* and am phlbole w ere I d e n t i f i e d from X -ray d iffra c to g ra m B . An a tte m p t was made t o q u a n tify th e s e m in e ra ls u s in g th e te c h n iq u e o f F le is c h e r (19T0) b u t abundances a r e o n ly p re c lB e t o an o r d e r o f m agnitude and hence a r e n o t p r e s e n te d . The d e te rm in a tio n s o f F le is c h e r (1 9 7 0 ), however* a r e a p p lic a b le to t h i s r e s e a r c h s in c e th e Bame g e n e r a l re g io n was s tu d ie d i n b o th p ro j e c t s . He found t h a t q u a r tz was th e m ost ab u n d an t n o n -c la y m in e ra l a v e ra g in g ab o u t 20% o f th e t o t a l se d im en t w e ig h t ( 62 m ic ro n s ). Q u artz was fo llo w e d i n abundance by p la g io c la s e (5%)* K -fe ld s p a r ( l.5 J t) and am phlbole ( 0 .5 £ ) . C lay M in e ra ls C lays (p h y l l o s i l i c a t e s ) w ere o n ly d e te rm in e d t o th e g ro u p l e v e l . C h lo rite * k a o l i n i t e , i l l i t e * and m o n tm o rlllo n ite w ere i d e n t i f i e d . In a d d itio n to th e s e g ro u p s h a l l o y s l t e was re c o g n iz e d In th e sam p les. I t 1 b d is tin g u is h e d by a low s h o u ld e r on th e h ig h angstrom s id e o f th e 7A peak i n th e g ly c o la te d m ounts (B rin d le y * 1 9 6 1 ). F le is c h e r (1970) r e p o r te d th e p re s e n c e o f t a l c / p y r o p h y l l i t e * v e r m ic u llte * b e l d e l l l t e * and an ex p an d ab le m ix e d -la y e r c la y te n d in g to w ard m o n tm o rlllo n ite . The l i s t e s ta b lis h e d by t h i s s tu d y can be augm ented t o in c lu d e th e s e c la y s . A ll o f th e c la y s i d e n t i f i e d in t h i s stu d y w ere p r e s e n t i n a l l 100 101 c o re s a n d t I t I s presum ed, th e c la y s re c o g n ise d by F le is c h e r (1970) In h is more d e t a i l e d s tu d y a re u b iq u ito u s a s w e ll. C h lo r ite p e rc e n ta g e , w hich p ro b a b ly a ls o in c lu d e s v e r m ic u llte , la th e o n ly c la y w hich shows a p r o c l i v i t y to change w ith d e p th i n t o th e c o re . I t s p e rc e n ta g e , i f I t does c h an g e, d e c re a s e s ( F ig s , 2 7 -3 3 ). The o th e r m ajo r c la y s ( k a o l i n i t e , i l l i t e , and m o n tm o rlllo n ite ) v a ry c o n s id e ra b ly w ith d e p th . I l l i t e i s th e m ost c o n s is te n t o f th e g ro u p , w ith k a o l i n i t e and m o n tm o rlllo n ite show ing a h ig h d e g re e o f s c a t t e r . D isc u ssio n B ecause o f th e u b iq u ito u s p re se n c e o f th e common n o n -c la y m ine r a l s , r e le a s e o f th e m ajor c a tio n s th ro u g h w e a th e rin g o f th e s e can o c c u r. T hus, K may be r e le a s e d by o r th o c la s e , Na and Ca ^ by p la g io c la s e , and p o s s ib ly a l l o f th e above p lu s M g+^ by am p h lb o le. The c la y s th e m selv e s can re a c h an e q u ilib riu m w ith th e s o lu tio n and may be r e l e a s i n g , a l b e i t in c o n g r u e n tly , c a t i o n s , S i0 2 (A q )' an<* A1(0H)^_ in to th e i n t e r s t i t i a l w a te r s . These r e a c tio n s a re d i s t i n c t from c a tio n exchange and u n lik e c a tio n exchange t h e i r e x te n t i s la r g e ly t h e o r e t i c a l . G a rre ls and M ackenzie (1971) and H elgeson e £ a l^ (1969) have p l o t t e d s t a b i l i t y f i e l d s w hich may be a p p lie d to th e m arin e en v iro n m en t . The d e c re a se in c h l o r i t e down th e c o re s i s m a n ife s te d p a r t i c u l a r l y in San N ic o la s B a sin . T h is o u te r b a s in , w hich i s alm o st d i r e c t l y in th e p a th o f th e southw ard flo w in g C a lif o r n ia C u r r e n t, r e c e iv e s much o f i t s c h l o r i t e from th e n o rth ( F le is c h e r 1 9 7 0 ). I t i s surm ized t h a t th e h ig h e r s e d im e n ta tio n r a t e d u rin g th e l a s t s ta n d o f th e s e a p e r - Figure 27- R e la tiv e abundance in c la y m in era ls, baaed on 100J( c la y s , v s . depth in core (C ■ C h lo r ite , K * K a o lin ite , I * I l l i t e , M * M on tm orlllon ite). C o re: 16991 102 1 6 9 9 1 I o V & J i " & t o o o> *0 200. 905 4 0 6 0 80 » ■ . 1 * r 100 Figure 28. R ela tiv e abundance In cla y m inerals based on lOOjf c la y s , v s. depth in core (C ■ C h lo r ite, K ■ K a o lin ite , 1 « I l l i t e , M * M ontm orlllon ite). C ore: 1699U 10lt core 20 * i 16994 4 0 6 0 8 0 I I 100. C\K M «a J * r ft 200. <0 315 10 0 Figure 29 . R ela tiv e abundance in cla y m inerals based on 100J( c la y s , v s . depth in core (C • C h lo r ite , K ■ K a o lin ite , I * I l l i t e , M * M ontm orlllonite). C o re: 16996 106 107 16996 1 0 0 00 - Q 200 270 Figure 30 R e la tiv e abundance in c la y m in e ra ls, baaed on 100JE c la y s , v s . depth in core (C ■ C h lo r ite , K ■ K a o lin ite , I * I l l i t e , M ■ M o n tm o rlllo n ite). C o re : 16997 108 depth i n core 109 16997 I OO 6 0 • 0 4 0 20 100 200, BIO Figure 31• R ela tiv e abundance in cla y m inerals based on 100$ c la y s , v s . depth in core (C * C h lo r ite , K * K a o lin ite , I ■ I l l i t e , M * M ontm orlllon ite). C o re; 17807 110 core 17807 Figure 32 R e la tiv e abundance in c lo y m in e ra ls, based on lO OJf c la y s , v s . depth in core ( C ■ C h lo r ite , K “ K a o lin ite , I ■ I l l i t e , M * M o n tm o rlllo n ite). C o re : 1 7 8 1 1 112 113 17811 20 £ 1 0 0 ' o 4 J K a 0 ) *0 200 4 0 6 0 275 A 52. M too ■ F ig u re 33* R e la tiv e abun d an ce i n c la y m in e ra ls b a a e d on lOOjt c l a y s , v s . d e p th i n c o re (C * C h l o r i t e , K ■ K a o l i n i t e , I ■ I l l i t e , M ■ M o n tm o r illo n ite ) . C o re: ISU36 llU 115 RELATIVE CL AT MINERAL % 18436 6.0 4 .0 8.0 1 0 0 Q 100- 2 6 3 116 m ltte d a d i l u t i o n o f th e n o rm al c h l o r i t e lo a d v h ic h g r a d u a lly a b a te d w ith tim e . T h ia h y p o th e s is i s i n a c c o r d w ith t h a t o f f e r e d by F l e i s c h e r (1970) t o e x p la in th e same s i t u a t i o n . D is g e n e tic r e a c t i o n s , i f o c c u r r in g , do n o t a p p e a r t o in v o lv e m a jo r s t r u c t u r a l c h a n g e s. No new c la y s a p p e a r I n th e c o r e s a t any p a r t i c u l a r l e v e l , n o r do es any p a r t i c u l a r c la y I n c r e a s e I n o r d i n a t e l y o r show a d i f f e r e n t d e g re e o f c r y s t a l l i z a t i o n w ith d e p th below th e i n t e r f a c e . F u r th e r , th e m o n tm o r lllo n ite i s u n v a ry in g i n I t s expanded p eak p la c e m e n t. I n d ic a t in g a la c k o f change to w a rd a m ore l l l i t i c c h a ra c t e r . F i n a l l y , F l e i s c h e r (1970) fo u n d no e v id e n c e o f d la g e n e tlc change i n t h e m ix e d -la y e r c la y s th e m s e lv e s o r th e b e i d e l l l t e p e r c e n ta g e s . The o n ly re m a in in g c la y w hich m ig h t p o t e n t i a l l y b e in v o lv e d i n a d i a - g e n e tlc r e a c t i o n i s h a l l o y s i t e . TEXTURAL ANALYSIS Mean g r a in s i z e and s o r t i n g v a lu e s v e r e c a l c u l a t e d u s in g th e moment m ethod. No m ajo r tr e n d s a r e shown i n F ig u re s 3^-UO, h u t mean g r a in s i z e does d is p la y a a l i g h t ten d e n c y to w ard a d e c re a s e w ith d e p th i n c o r e . A lthough th e r e i s a v a r i a t i o n i n a b s o lu te mean g r a in s i z e , th e mode w ould h e p la c e d aro u n d 8 m icro n s ( f i n e to v e ry f in e s i l t ) . S o r tin g v a lu e s a re t y p i c a l l y around 2 0 w hich i s c o n s id e re d p o o r (F o lk , 1 9 6 6 ). 117 Figiore 3U. Mean grain s iz e and so r tin g v s . depth in core. Core: 16991 1X8 depth i n core (C M ) 1X9 Textural Analysis 16991 Sorting Mean Grain Site 1 0 0 200 9 0 0 Figure 35. Mean grain s iz e and s o r tin g v s . depth In co re. Core: 1699U 120 depth i n core (C M ) 121 Textural Analysis 1 6 9 9 4 Sorting Moon Groin Size 100 200 3 0 0 Figure 36 . Mean grain s iz e and so r tin g v s . depth in c o r e . Core 1 16996 122 depth i n core (CM) 1 2 3 T extu ral A n alysis 16996 Sorting Moan Grain Slzo 100 200 3 0 0 F ig u re 37* Mean g r a in s iz e and s o r t i n g v s . d e p th i n c o re . C o re: 16997 12U depth i n core (C M ) T extu ral A n alysis 16997 8o rtln g Mean Groin Size 1 0 0 200 5 0 0 Figure 38. Mean grain e ls e and so r tin g v s. depth in core. Core: 17807 126 depth i n core (C M ) T extu ral A n alysis I7 8 0 T Sorting Moon Grain Slzo 1 0 0 200 9 0 0 Figure 39. Mean grain s iz e and s o r tin g v s . depth in co re. Core: 17811 128 depth i n core (C M ) T extu ral A n alysis 17811 Sorting Moan Grain Slzo * 100 200 3 0 0 Figure UO. Mean g ra in s iz e and s o r tin g v s . depth in co re. Core: 18^36 130 131 T extu ral A n alysis 18436 Alton Grain Slzo 8 o rtln g IOO 200 3 0 0 GENERAL DISCUSSION C hem ical R e la tio n e h ip s P r i o r t o t h i s th e s o l i d and l i q u i d phaseB have b een I s o l a t e d from one a n o th e r w ith r e g a rd t o t h e i r p o t e n t i a l i n t e r a c t i o n . The d i s c r e t e l i n e s o f e v id e n c e may b e e n tw in e d now, t o d e m o n stra te th e p o s s i b i l i t y and e x te n t o f e a r ly d ia g e n e s is . A c c o rd in g ly , p o re w a te r c h e m is try , b u lk c h e m istry and m in e ra lo g y d a ta a r e t r e a t e d below as one e n t i t y , t o th e e x te n t t h a t t h i s i s p o s s ib le . In o r d e r t o p ro v id e a more co m p lete fram ew ork t o e s tim a te changes i n th e s o l i d p h a s e s , c la y m in e ra lo g y and b u lk c h e m istry d a ta w ere u n ite d on an i d e a l b a s i s . C a lc u la tio n s w ere made u s in g th e c la y m in e ra l p r o p o rtio n s from t h i s stu d y and th e ra n g e in ch em ical compo s i t i o n p u b lis h e d f o r p u re c la y s (Weaver and P o l l a r d , 1973» G rim , 1 9 5 3 ). ThuB, g iv e n th e r e l a t i v e abundance o f th e d i f f e r e n t c la y s in a p a r t i c u l a r sam p le, a minimum, a v e ra g e , and maximum o x id e p e rc e n ta g e w hich c o u ld be e x p e c te d f o r each s p e c ie s was d e te rm in e d . The f iv e o x id e p e rc e n ta g e s (S iO g , Al^O^, MgO, K^O, and NagO) w ere a d ju s te d t o 100$ i n o rd e r to be on th e same b aB ls a s th e o b se rv e d v a lu e s . In e v e ry c a s e o b se rv e d s i l i c a i s w ith in l i m i t s im posed by th e p re v io u s a n a ly s e s o f p u re c l a y s , and i n g e n e r a l i s alm o st alw ays v e ry c lo s e t o th e i d e a l a v e ra g e v a lu e . D e v ia tio n s from th e i d e a l may be a t t r i b u t e d t o ch an g in g am ounts o f n o n -c la y s i n t h a t th e 15-30$ ran g e 132 133 may n o t be v a l i d i n e v e ry c a a e . Al^O^ c o n tin u e a t o m ir r o r th e SiO^ v a lu e s and i s somewhat lo w e r, a s a g e n e r a l i z a t i o n , th a n th e id e a l v a lu e . Once a g a in i t s h o u ld be n o te d t h a t v a r i a t i o n s o f n o n -c la y p e r c e n ta g e s o u ts id e th e assum ed l i m i t s c o u ld a c c o u n t f o r th e f lu c tu a ti o n s shown. T h at I s , in c r e a s e d q u a r tz beyond th e ran g e w ould make 810^ more p red o m in a n t r e l a t i v e t o th e t o t a l w eig h t and Al^O^ l e s s a b u n d a n t. The c o n v e rse i s alB o t r u e . T h u s, th e symmetry may be e x p la in e d . I t i s unknown why th e Al^O^ v a lu e s a r e lo w er th a n th e i d e a l ra n g e . Alu m in u m -d e fic ie n t c la y s in th e so u rc e a r e a s I s a p o s s i b i l i t y , b u t no a n a ly s e s w ere p erfo rm ed t o s u b s t a n t i a t e o r r e j e c t t h i s e x p la n a tio n . +2 M g - MgO System C om parison o f th e o b se rv e d and i d e a l MgO, K^O, and Na^O v a lu e s a r e shown i n F ig u re s U l-U j. As was m en tio n e d , i n 5 o f 7 c o re s M gO p e rc e n ta g e d e c re a s e s w ith d e p th d a t a , and t h i s o v e r a l l tr e n d I s im posed on an I n i t i a l d e c r e a s e , th e d e c re a se i n th e f i r s t m e te r. I t can be seen i n th e f i g u r e s , how ever, t h a t th e id e a l M gO p e rc e n ta g e s g e n e r a lly do n o t p a r a l l e l th e o b se rv e d o n e s , and in f a c t o f te n tr e n d i n th e o p p o s ite d i r e c t i o n . F u rth e rm o re , th e o b se rv e d v a lu e s a r e commonly h ig h e r th a n th e i d e a l mean v a lu e s , a lth o u g h m o stly w ith in th e p ro p e r r a n g e , and te n d t o ap p ro ach one a n o th e r w ith d e p th i n t o th e c o re . A lso i n r e l a t i o n t o MgO, a rev iew o f F ig u re s 2 -8 shows t h a t in e v e ry in s ta n c e th e g ro s s p o re w a te r and o x id e tr e n d s a re c o m p a tib le . In s h o r t , MgO abundance does n o t behave a c c o rd in g t o th e i m p l i c i t p r e d ic t i o n o f th e i d e a l , b u t i t i s s t r i k i n g l y in te rn e s h e d w ith th e co n cen - +2 t r a t i o n s o f M g . The v e ry Im p o rta n t e x c e p tio n t o t h i s , how ever, i s F ig u re U l. C a lc u la te d i d e a l ra n g e (b a a e d on r e p o r te d p u re c la y c o m p o s itio n s ) and o b s e rv e d ra n g e (h a tc h u re d sw a th e ) I n o x id e s b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th i n c o r e . Range i n i d e a l d a ta was d e te rm in e d by t h e v a r i a t i o n i n p u re c la y c o m p o sitio n an d p o s s i b l e n o n -c la y m in e ra l ab u n d an ce ; th e ra n g e i n o b s e rv e d d a t a b a a e d o n ly on p o s s i b l e v a r i a t i o n o f n o n -c la y m in e ra l abun d a n c e . C o re : 16991 13J+ Observed and Idea! Chemical Compositions (%) 16991 MgO K 20 NotO 24682 4 6 12 F ig u re k2. C a lc u la te d I d e a l ra n g e (b a s e d on r e p o r te d p u re c la y c o m p o s itio n s ) an d o b s e rv e d ra n g e ( h a tc h u re d sw a th e ) i n o x id e s b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th i n c o r e . Range i n i d e a l d a ta was d e te rm in e d by t h e v a r i a t i o n i n p u re c la y c o m p o sitio n an d p o s s i b l e n o n -c la y m in e ra l a b u n d a n c e ; t h e ra n g e in o b se rv e d d a ta b a s e d o n ly on p o s s i b l e v a r i a t i o n o f n o n -c la y m in e ra l abun d a n c e . C o re: 1699U 136 Observed and Ideal Chemical Compositions (%) 16994 M9 O K 20 N atO 24682 4 6 12 F ig u re J+3. C a lc u la te d I d e a l ra n g e (b a ae d on r e p o r te d p u re c la y c o m p o sitio n s) and o b se rv e d ran g e (h a tc h u re d sw ath e) in o x id e s b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th In c o r e . Range In I d e a l d a ta was d e te rm in e d by th e v a r i a t i o n i n p u re c la y c o m p o sitio n and p o s s ib le n o n -c la y m in e ra l ab u n d an ce; th e ra n g e in o b se rv e d d a ta b a s e d o n ly on p o s s ib le v a r i a t i o n o f n o n -c la y m in e ra l abun d an ce . C o re: 16996 130 Depth i n Core (CM) Observed and Ideal Chemical Compositions (%) 16 9 9 6 MflO KzO NatO 200- 3 0 0 - 1 3 9 F ig u re Uh. C a lc u la te d i d e a l ran g e (b a se d on r e p o r te d p u re c la y c o m p o sitio n s) and o b se rv e d ra n g e (h a tc h u re d sw ath e) i n o x id e s b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th i n c o re . Range i n id e a l d a ta was d ete rm in e d by th e v a r i a t i o n i n p u re c la y co m p o sitio n and p o s s ib le n o n -c la y m in e ra l ab u n d an ce; th e ran g e In o b se rv ed d a ta b a s e d o n ly on p o s s ib le v a r i a t i o n o f n o n -c la y m in e ra l abun d an ce. C o re: 1699T lUO Observed and Ideal Chemical Compositions (%) 16997 M tfO K x O HatO 2468 2 4 6 123 F ig u re 1 + 5 * C a lc u la te d I d e a l ra n g e (b a se d on r e p o r te d p u re c la y c o m p o sitio n s) an d o b se rv e d ra n g e (h a tc h u re d sw ath e) In oxideB b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th i n c o re . Range i n id e a l d a ta was d eterm in e d by th e v a r i a t i o n i n p u re c la y c o n p o s itio n and p o s s ib le n o n -c la y m in e ra l abundance; th e ra n g e i n o b se rv e d d a ta b a se d o n ly on p o s s ib le v a r i a t i o n o f n o n -c la y m in e ra l abun dan ce. Core i 17607 1U2 Observed and Ideal Chemical Compositions (%) 17807 MgO K 20 No to 24682 4 6 123 F ig u re U6. C a lc u la te d i d e a l ra n g e (b a se d on r e p o r te d p u re c la y c o m p o sitio n s) and o b se rv e d ra n g e (h a tc h u re d sw ath e) i n o x id e s b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th i n c o re . Range i n id e a l d a ta was d e term in e d by th e v a r i a t i o n i n p u re c la y c o m p o sitio n and p o s s ib le n o n -c la y m in e ra l ab u n d an ce; th e ra n g e In o b se rv e d d a ta b a sed o n ly on p o s s ib le v a r i a t i o n o f n o n -c la y m in e ra l ab u n d an ce. Core i 178 1 1 ll*U Depth i n Core (CM) Observed and Ideal Chemical Compositions (%) 17811 M«0 K20 NotO 1 0 0 200 3 0 0 F ig u re U 7 . C a lc u la te d I d e a l ra n g e (b a s e d on r e p o r te d c la y c o m p o s itio n s ) an d o b s e rv e d ra n g e ( h a tc b u re d sw ath e) I n o x id e s b a s e d on r e l a t i v e c la y m in e ra l d i s t r i b u t i o n v s . d e p th i n c o r e . Range i n i d e a l d a ta was d e te rm in e d b y th e v a r i a t i o n I n p u re c la y c o m p o sitio n an d p o s s i b l e n o n - c la y m in e ra l a b u n d an ce; th e ra n g e in o b s e rv e d d a ta b a s e d o n ly on p o s s i b l e v a r i a t i o n o f n o n -c la y m in e ra l abun d a n c e. C o re: 1 8U 36 1 1* 6 Observed and Ideal Chemical Compositions (%) 18436 MfO K2O NotO 2 4 6 6 2 4 6 8 1 2 3 - - - A « ■ I l . _ ■ * t h a t I n t h e to p e o f t h e c o re s p o r e v a te r d a ta and h u lk c h e m ic a l d a ta a r e m ir r o r im a g e s. S t i l l , t h e o v e r a l l f a c t s a r e i n d e f ia n c e o f th e m o d els o f D re v e r (1971) an d S h o lk o v itz (1 9 7 2 ). The h a s ic c o n tr a d ic t i o n s a r e t v o f o l d . F i r s t , MgO abundance d e c r e a s e s r a t h e r th a n i n c r e a s e s down th e c o r e s : c o n tr a r y t o t h e p r e d i c t i o n o f th o s e tv o a u th o r s . S e co n d , c o n c e n tr a tio n in th e i n t e r s t i t i a l f l u i d i s a c c o r d a n t, n o t d i s c o r d a n t , t o t h e tr e n d p r e v a i l i n g i n th e s o l i d p h a s e . The m odels v e r e a p p lie d t o re d u c in g e n v iro n m e n ts , h o w ev er, and t h i s w r i t e r i s I g n o ra n t o f th e e x a c t re d o x s t a t e o f th e se d im e n ts sam pled f o r t h i s s tu d y . Emery ( i 9 6 0 ) c h a r a c t e r iz e d th e b a s in f l o o r s u n d e r c o n s id e r a t i o n , a t l e a s t t o th e depthB o f p i s t o n c o r e p e n e t r a t i o n , a s b e in g o x i d i z i n g , a lth o u g h seme re d u c in g c o n d itio n s w ere e n c o u n te re d b elo w tv o m e te r s . B rooks e t a l . (1966) p r e s e n te d d a ta on S a n ta C a ta lin a and S a n ta Cruz B a s in s an d showed them t o b e w eak ly o x id iz in g i n th e l o c a l e s s tu d i e d b y them . A tte m p ts w ere made d u rin g t h i s I n v e s t i g a t i o n t o o b ta in Eh m easu rem en ts b u t th e s e w ere u n s u c c e s s f u l b e c a u s e o f ex c e s s iv e In s tr u m e n t d r i f t . N o n th e le s s , a d i s t i n c t HgS o d o r was p r e s e n t when t h e c o re s e c t io n s b etw ee n 1 , J a and 2 .5 m w ere o p en ed . S o , th e e x a c t re d o x s t a t u s re m a in s a m y ste ry f o r th e p r e s e n t . The o n ly con c l u s i v e s ta te m e n t w hich can be made i s t h a t D re v e r and S h o lk o v itz m o d els do n o t a p p ly t o t h i s e n v iro n m e n t, r e g a r d l e s s o f w hat c o n d itio n s e x i s t . The r e s u l t s o f th e i r o n a n a ly s e s a r e a p p r o p r ia te t o t h i s d i s c u s - +2 s io n . B o th m odels u se d t o e x p la in t h e b e h a v io r o f Mg - MgO sy stem r e q u i r e s a r e d u c tio n o f Fe i n th e s o l i d , i t s s u b se q u e n t re m o v a l, and em placem ent o f Mg. The i r o n msy b e i n th e form o f an o x id e c o a tin g 11+9 o r w ith in t h e c la y i t s e l f . F ig u re 26 im p lie s t h a t i n t h e t h r e e b a s in s s tu d i e d f r e e i r o n o x id e , i f i t shows a p r e f e r e n c e a t a l l , te n d s t o in c r e a s e down t h e c o r e s , n o t d e c r e a s e . Thus i t does n o t a p p e a r to b e rem oved w ith d e p th i n t h e c o r e . T o ta l i r o n m inus " f r e e ir o n " ( F ig . 25) do es n o t e x h i b i t a c o n s i s t e n t t r e n d e i t h e r . T h u s, t h e r e s u l t s o f t h i s s tu d y c o n firm o n ly one s id e o f th e D re v e r o f S h o lk o v itz m o d e ls. S p e c i f i c a l l y , Mg te n d s t o d e c r e a s e , b u t F e , I n e i t h e r c a s e , d o e s n 't and MgO d o e s . The p re v io u s c o n c lu s io n i s r e a f f ir m e d ; t h e s e m o d els do n o t a p p ly t o th e e n v iro n m e n ts o f t h i s s tu d y . What c o u ld a c c o u n t f o r th e o b se rv e d b e h a v io r? Viewed from a +2 c h e m ic a l s ta n d p o i n t , th e s o l i d p h a se m ust b e e f f u s in g Mg w ith d e p th , b u t t h i s does n o t f i t th e o v e r a l l p a t t e r n o b s e rv e d in t h e p o re w a te r . A ls o , th e c o re ta k e n from th e s o u th e r n p a r t o f S a n ta Cruz b a s in (17611) e x h i b i t s a d i s t i n c t in c r e a s e i n b o th th e s o l i d and i n t e r s t i t i a l f l u i d s ( F ig s . 7 and 2 1 ). H ie d i s s o l u t i o n o f c a rb o n a te s w ith t h e i r p e r c e n ta g e o f MgCO^ c o u ld n o t a c c o u n t f o r th e phenom enon. A lth o u g h c a rb o n a te tr e n d s f o r t h r e e o f t h e c o re s from t h i s s tu d y (one from e a c h +2 b a s in by C la n c y , 1973) h av e a p o s i t i v e c o r r e l a t i o n w ith Mg and M gO tr e n d s i n tw o o f t h e t h r e e caseB, w ith t h e t h i r d c a s e c o n s id e re d "tin - c e r t a i n , " th e Ca tr e n d s do n o t p a r a l l e l th e p e r c e n ta g e s o f CaCO^ w ith d e p th b elo w th e i n t e r f a c e . And, u n le s s in c o n g ru e n t d i s s o l u t i o n +2 i s ta k in g p l a c e , one s h o u ld o b s e rv e a c o n c o rd a n c y b etw een t h e Ca +2 and Mg t r e n d s , w hich i s n o t th e c a s e . P e rh a p s a key t o t h i s enigm a i s t h e r e l a t i o n s h i p o f a b s o lu te v a lu e s b etw een Mg and MgO. D rev er (1971) h a s com puted t h a t f o r a 150 se d im e n t c o n ta in in g 50$ w a te r , a change fro m 2 .0 0 $ t o 2 .0 2 $ (1$ ch an g e ) +2 n e c e s s i t a t e s a 17$ d e c r e a s e I n I n t e r s t i t i a l Mg (assu m in g a n o rm al +2 a b s o lu te ra n g e f o r Mg ) . The ra n g e o f v a lu e s f o r MgO (2-U $) I s s e v e r a l o r d e r s o f m a g n itu d e g r e a t e r th a n c o u ld b e a c c o u n te d f o r b y an +2 in tim a te d ep en d en ce w ith p o re w a te r Mg . I t i s n o te w o rth y t h a t th e c l a s s i c symmetzy b etw een p o re w a te r and s o l i d I s s e e n In th e to p o f +2 th e c o r e s , and f o r t h i s re a s o n I t I s b e lie v e d t h e Mg i s f i l l i n g ex change s i t e s i n t h i s i n t e r v a l . I t may be c o n c lu d e d t h a t any p o s s i b l e d l a g e n e t l c r e a c t i o n s o c c u r - +2 r i n g w ith r e s p e c t t o th e Mg - MgO sy ste m w ould b e sh ro u d e d by th e d i f f e r e n c e s i n m agnitude* S e d im e n ta tio n e f f e c t s may b e e n t i r e l y r e s p o n s ib le f o r th e change i n MgO p e r c e n ta g e , a t l e a s t t o th e d e g re e t h a t th e d a t a may b e a n a ly z e d . An i n f l u x o f c l a y s , p a r t i c u l a r l y c h l o r i t e and v e r m ic u li t e , w ith h ig h Mg c o n te n ts may h av e o c c u rre d as th e re la r- t i v e im p a c t o f d i f f e r e n t s o u rc e a r e a s changed w ith t h e r i s e i n s e a l e v e l . No d la g e n e tlc a c t i v i t y can b e s u b s t a n t i a t e d . K* - K^O S ystem R e f e r r in g t o F ig u re s Ul an d UT, th e o b s e rv e d and i d e a l K^O v a lu e s g e n e r a l l y I n c r e a s e . T h e r e f o r e , th e p e r s i s t e n t tr e n d o f K^O i n th e o b se rv e d c a s e s I s p u r e ly a m a n if e s ta tio n o f " w h a t's su p p o sed t o b e . " Of n o te i s t h a t th e K^O o b s e rv e d p e r c e n ta g e s a r e commonly lo w e r th a n t h e i r I d e a l c o u n te r p a r ts an d te n d t o a p p ro a ch t h e lo w e r ra n g e o f th e " p r e d ic te d " v a lu e s w ith d e p th . T h is i s c o m p a tib le w ith th e con c l u s i o n o f Manhelm an d S a y le s ( i n p r e s s ) . H ow ever, th e y c a l l f o r a d e c r e a s e i n K+ c o n c e n tr a tio n i n t h e i n t e r s t i t i a l w a te rs t o s u p p ly t h e 151 ■ o lid p h a s e . Such a c irc u m sta n c e was o b serv ed In th e u p p e r m e te r o f s e d im e n t, b u t n o t o v e r a l l . W ith in th e u p p e r s e c t io n , th e p r o p o r tio n a te change was o f th e c o r r e c t o r d e r o f m agnitude ( F ig s . 2 -8 and 4 1 -4 7 ) and th u s t h i s ty p e o f d la g e n e tlc r e a c tio n may be o c c u rrin g t h e r e . I l l l t e , a K -m in e ra l, I s th e m ost ab undant c la y p r e s e n t In th e s e d im e n ts , and th e a b i l i t y o f montmor11l o n l t e to exchange c a tio n s I s w e ll known ( s e e , fo r ex am p le, B e rn e r, 1971; G rim , 1 9 5 3 ). As was d is c u s s e d p r e v io u s ly , th e a b s o lu te change In p o re w a te r K + v a lu e s w i l l f i t In to th e a b s o lu te change in ex ch an g eab le K + re p o rte d by C lancy (1 9 7 3 ). I t i s p o s s i b l e , t h e r e f o r e , t h a t t h i s r e a c tio n may be ta k in g p la c e . +2 L ike th e M g - M gO sy stem , how ever, th e dom inance o f o th e r f a c t o r s m asks a re a s o n a b le c o n firm a tio n o f t h i s r e a c t i o n . Most s i g n i f ic a n t I s th e e n ric h m e n t o f th e K + c o n c e n tr a tio n a s compared to norm al s e a w a te r. T h is e n ric h m e n t I s f a r In e x c e ss o f w hat may be a t t r i b u t e d to te m p e ra tu re o f sq u e e z in g e f f e c t s , w hich may be c o n s id e ra b le (B ls - c h o ff e t a l . , 1971; M an g elsd o rf e t a l . . 1 9 6 8 ). H ence, an In s i t u so u rc e o f K*’ m ust e x i s t In th e s e se d im e n ts . I t I s surm ized t h a t K- f e ld s p a r may p ro v id e th e n e c e s s a ry q u a n t i t i e s o f th e c a tio n to acco u n t f o r th e I n c r e a s e . M urray (1973) a s c e r ta in e d t h a t t h i s was therm odyna m ic a lly p o s s i b l e , and h i s o p in io n c o rre sp o n d s w ith S le v e r et_ a l . (1965) and Brooks e £ a l . (1 9 6 8 ), to name a few . C o n tra d ic to ry to t h i s o p in io n i s t h a t o f D rev er (1971) who f e e l s t h a t d i s s o l u t i o n o f K -fe ld s p a r co u ld n o t s u p p ly K* f a s t enough e s p e c i a l l y a t th e in t e r f a c e t o e x p la in th e d is c re p a n c y . T h is k i n e t i c problem may be a u th e n tic , b u t I t i s a ls o p o s s ib le t h a t o n ly a segm ent o f th e d i f f u s io n g r a d ie n t I s b e in g ob s e rv e d , and th e r e need n o t be a t i g h t c o r r e l a t i o n betw een sed im en t and 152 I n t e r s t i t i a l w a te r c o m p o sitio n a t th e same l e v e l . The K + - KgO sy stem i n th e b a s in s s tu d ie d may be sunanarised by sa y in g t h a t an u p ta k e o f K+ by th e c la y s i s a d e f i n i t e p o s s i b i l i t y , b u t e v id e n c e f o r t h i s does n o t encom pass th e e n t i r e le n g th s o f th e c o r e s , b u t o n ly th e to p m e te r. KgO c o n te n t in c r e a s e s w ith d e p th in ac co rd a n ce w ith th e change in m in era lo g y } no d la g e n e tlc r e a c t i o n , t h e r e f o r e , need be in v o k ed a s an e x p la n a tio n . C onvergence o f th e low KgO v a lu e s w ith th e " p r e d ic te d " may im ply an u p ta k e to w a rd th e norm , b u t , t o r e i t e r a t e , th e p o re w a te r d a ta c a n n o t v e r i f y t h i s b e c a u se i t may be c o n tr o lle d by a d i s s o l u t i o n o f f e ld s p a r — th u s s h e a th in g th e I n t e r a c t i o n o f s o l i d and l i q u i d . T h at i s , th e c la y s may be rem oving K + a t a much low er r a t e th a n i t i s b e in g d if f u s e d i n t o th e p o re w a te r. Ha+ - Ha^O System Com parison o f th e o b se rv e d and i d e a l f o r t h i s system r e v e a ls t h a t i n a lm o st e v e ry in s ta n c e th e a n a l y t i c a l d a ta b eh av es disharm on io u s ly w ith r e s p e c t to th e i d e a l ( F ig s . 1 * 1 — J+T). S in c e no c o n s is te n t t r e n d in e i t h e r p r e v a i l s th e c o n tr a d ic to r y a c tio n becom es e x c e e d in g ly d i f f i c u l t t o r e s o lv e . O th er f a c t s w hich m ust b e c o n s id e re d a r e t h a t i n t e r s t i t i a l w a te r c o n c e n tr a tio n o f Ma+ a ls o h as a p r o c l i v i t y f o r r e f l e c t i n g , r a t h e r th a n p a r a l l e l i n g , th e b u lk ch em ic al tr e n d s (F ig s . 2 -8 and ^1 -U 7 ), t h a t Ha+ u s u a lly d e c r e a s e s , th e n in c r e a s e s in th e f i r s t m e te r o f se d im e n t, i s g e n e r a lly s l i g h t l y below b o tto m w a te r in c o n c e n tr a tio n , and t h a t Na^O v a lu e s a r e c o n s is t e n t l y above th e expec te d by an a la rm in g m a rg in . 153 B efo re a s t r u c t u r i n g o f th e s y s te m 's c h a r a c t e r i s t i c s can be acco m p lish ed a p o t e n t i a l so u rc e o f e r r o r m ust be d isc u sse d * I f th o ro u g h w ashing o f th e squeezed ; ak es i s n o t a c h ie v e d a NaCl r e s id u e may be p re s e n t w hich can o b v io u sly d e t r a c t from th e a c c u ra c y o f th e d a t a . The ab n o rm ally h ig h Na20 p e rc e n ta g e s may sim p ly be an a r t i f a c t o f in c o m p le te w ash in g . M indful o f t h i s p o s s i b i l i t y , th e fo llo w in g I n t e r p r e t a t i o n i s re n d e re d w ith a p p r o p r ia te a llo w a n c e s made. Exchange s i t e s may adm it Na+ a f t e r b u r i a l in th e s e b a s in s (C lan cy , 1 9 7 3 ), b u t th e t o t a l v a r i a t i o n o f th e Na+ c o n c e n tr a tio n c a n n o t be accom odated on su ch s i t e s (T ab le IV ). The i n i t i a l d e c re a s e m ight s u g g e st an u p ta k e on th e exchange s i t e s , e x c e p t t h i s i s commonly fo llo w e d by an in c r e a s e . U n less two d i f f e r e n t phenomena a r e In v o lv e d , t h i s i s u n te n a b le . In a d d itio n , th e Na20 v a lu e s a ls o d e c re a s e i n i t i a l l y , th e n I n c r e a s e . I t i s assum ed, how ever, t h a t th e p o re w a te r v a lu e s b e in g below bottom w a te r v a lu e s i n d ic a te an e a r ly rem oval from s o lu t i o n . Symmetry d is p la y e d in tre n d s f u r t h e r Im p lie s a s e n s i t i v e re sp o n se mechanism i s o p e r a tiv e . B u t, a s was s t a t e d e a r l i e r , exchange s lte B a lo n e can n o t e x p la in th e amount o f v a r i a t i o n , and th e b u lk ch em ical d a ta f o r Na20 may be b le m ish e d . T hus, o n ly an in c lu s iv e s ta te m e n t can be made: i t i s c e r t a i n l y p o s s ib le t h a t th e Na+ - NsjO sy stem i s p a r ta k in g in a d la g e n e tlc r e a c t i o n , b u t t h i s can n o t be proved u n e q u lv lo c a lly . S102(Aq) ~ S102 (w o rp h ) - m 2°3- s i 0 2 (Morph) ~ 3y*t ** The e x p e rim e n ts o f M ackenzie, a t a l . (1967) d e m o n stra te t h a t in s i l i c a - p o o r w a te rs c la y s w i l l r e le a s e s i l i c a up to q u a n t i t i e s a p p ro a - c h ln g 15 ppm. T h is i s c e r t a i n l y w ith in th e p ro p e r ran g e t o be con g ru e n t w ith th e v a lu e s o b ta in e d i n t h i s s tu d y . A ls o , th e S i O ^ ^ j tr e n d s g e n e r a lly d is p la y an i n i t i a l i n c r e a s e , a lth o u g h th e c o l l e c t i o n o f p r o f i l e s f o r a l l c o re s do n o t e x h i b i t a te n d e n c y f o r c o n s is te n t e n ric h m e n t o r d e p le tio n . N o n e th e le s s , an e a r ly d i s s o l u t i o n o f s i l i c a i s im p lie d . Once a g a in , t h e n , I t a p p e a rs t h a t th e to p s o f th e c o re s may b e m ore I n d ic a t iv e o f d la g e n e tlc e v e n ts th a n th e re m a in d e r. W ith re g a rd t o th e s i l i c a p ro b le m , e n ric h m e n t o f th e I n t e r s t i t i a l w a te r re d u c e s th e l i k e l i h o o d o f n e t s i l i c a rem oval i n t h i s en v iro n m e n t. A ls o , th e r e l a t i v e l y low l e v e l o f en rich m en t and t h e o v e r a l l ab sen ce o f n e g a tiv e tr e n d s s u g g e s ts t h a t a c o a tin g o f th e s i l i c a t e s o r s i l i ceo u s o rg an ism s t o i n h i b i t d i s s o l u t i o n i s n o t p r e s e n t. T h is b e l i e f i s s u p p o rte d by th e c la y m in e ra lo g y : no s e p l o l l t e o r o th e r p h ase was found w hich w ould b e c a p a b le o f s h e a th in g th e s i l i c a s o u rc e s . B io g e n ic s i l i c a tr e n d s f o r th e th r e e s e le c te d cores (one from each b a s in ) a r e e i t h e r a d e c re a s e (S a n ta C a ta lin a and San N ic o la s B a s in s) o r c o n sta n c y (S a n ta Cruz B a sin ) (F ig u re 2U). The g e n e ra l in c r e a s e o f th e S iO g ^ ^ j c o n te n t i n th e a p p r o p r ia te p o re w a te rs ( F ig s . 9 -1 1 ) and th e u n ifo rm l e v e l in th e S a n ta Cruz Core s u g g e st t h a t w hat h as become a h a llm a rk o f r e c o g n itio n f o r a d la g e n e tlc p ro c e s s e x i s t s . T h u s, i t i s te m p tin g t o s u g g e st t h a t d i s s o l u t i o n o f amor phous s i l i c a from o rg an ism s i s r e s p o n s ib le f o r th e r i s e i n i n t e r s t i t i a l w a te r c o n c e n tr a tio n s o f SiOg. The m agnitude o f change i n th e s o l i d SiOg i s , how ever, f a r i n e x c e s s o f what i s o b s e rv e d i n th e p o re w a te r. F u rth e rm o re , i t s h o u ld be n o te d t h a t th e a b s o lu te p o re w a te r s i l i c a v a lu e s o f th e th r e e c o re s do n o t d i f f e r i n o r d in a te ly even th ough th e 155 b io g e n ic s i l i c a , m a n ife s ts d e f i n i t e l y h ig h e r v a lu e s In th e S a n ta Cruz c o re . I t a p p e a rs , t h e r e f o r e , t h a t b e c a u se a m ass b a la n c e does n o t e x i s t , as was th e c a s e w ith o th e r sy stem s d is c u s s e d , an i n t e r p r e t a t i o n m ust a g a in be couched In q u e .llfy in g p h a s e s . Nam ely, c o n tr ib u tio n s by c la y s o r b io g e n ic s i l i c a may a c co u n t f o r th e s i l i c a en rich m e n t i n i n t e r s t i t i a l w a te r s , p a r t i c u l a r l y i n th e u p p er m e te r , b u t th e r e l a t i v e in f lu e n c e o f e i t h e r i s unknown. Coupled w ith t h i s problem i s th e in v o lv em en t o f amorphous alum ino s i l i c a t e s w ith d ia g e n e s ls . A cco rd in g t o th e m odel o f M ackenzie and C a r r e ls (1966) am orphous A l - s l l i c a t e abundance s h o u ld d e c r e a s e j n o t in c r e a s e , upon d e e p e r b u r i a l . T h is w ould be due t o a r e c o n s t i t u t i o n o f th e amorphous m a te r ia l i n t o a s tr u c t u r e d p h y l l o s l l i c a t e . Concom i t a n t w ith t h i s e v e n t, c a tio n s w ould be ta k e n i n t o th e new s t r u c t u r e and an a u th ig e n lc c la y w ould r e s u l t . And y e t , we have se e n t h a t amor phous A l - s l l i c a t e te n d s t o in c r e a s e down th e c o r e s , a h a p p e n sta n c e t h a t may be a t t r i b u t e d t o s e d im e n ta tio n r a t e phenom ena and n o t n e c e s s a r i l y t o d la g e n e tlc o n e s. D ia g e n e sls In C lays I s th e r e e v id e n c e f o r th e p re s e n c e o f a u th ig e n lc c la y s ? D la g e n e tlc r e a c t i o n s , i f o c c u r r in g , do n o t a p p e a r to in v o lv e m ajo r s t r u c t u r a l c h a n g es. No new c la y s a p p e a r i n th e c o re s a t any p a r t i c u l a r l e v e l , n o r does any p a r t i c u l a r c la y I n c re a s e in o r d in a te ly o r show a d i f f e r e n t d e g re e o f c r y s t a l l i z a t i o n w ith d e p th below th e i n t e r f a c e . F u r th e r , th e m o n tm o rillo n lte i s u n v a ry in g i n i t s expanded peak p la c e m e n t, I n d ic a tin g no change tow ard a more l l l i t l c c h a r a c te r . F i n a l l y , F le is c h e r (1970) fo u n d no e v id e n c e o f d la g e n e tlc change in t h e m ix e d -la y e r c la y e th e m se lv e s o r th e b e i d e l l i t e p e r c e n ta g e s . The o n ly rem ain in g c la y w hich m ig h t p o t e n t i a l l y be In v o lv e d i n a d la g e n e tlc r e a c t i o n i s h a l l o y s l t e . Weaver and P o lla r d (1973) s t a t e t h a t a p o s s i b l e c o n tl nnum e x i s t s b etw een amorphous alum l nos i l l c a te b and k a o l i n i t e w ith h a l l o y s l t e , a h y d ra te d v a r i e t y o f k a o l i n i t e o ccu p y in g th e c e n t r a l p o s it i o n . The s te p betw een th e i n i t i a l fo rm a tio n o f a llo p h a n e ( a m o rp h o u s -A l- s llic a te ) and th e p re s e n c e o f d i s t i n c t h a l l o y s l t e r e q u ir e s an o r g a n iz a tio n o f th e s p h e r i c a l a llo p a n e p a r t i c l e s i n t o f i b e r s o r tu b e s . More e x te n s iv e s t r u c t u r i n g and d e h y d ra tio n r e s u l t i n a k a o l i n i t e . S in c e a l l t h r e e o f th e s e m a te r ia ls e x i s t in th e b o rd e rla n d sed im e n ts a r e a c tio n i s p o s s i b l e , b u t n o t p ro b a b le . F i r s t , a s h as b een d e s c rib e d , p e r c e n t amorphous a lu m in o s ilic a te in c r e a s e s down tv o o f th e c o re s and i s unchanged down th e t h i r d — a f a c t e x p la in a b le by means o th e r th a n d ia g e n e s ls and w hich c e r t a i n l y does n o t d e n o te a re s t T a rin g i s ta k in g p la c e . S econd, th e h a llo y - a l t e peak a re a s have a c o n s is te n t r e l a t i o n s h i p t o th e k a o l i n i t e peak a r e a s , in d ic a tin g t h a t an in c r e a s e o f h a l l o y s l t e i s n o t ta k in g p la c e . Of c o u rs e , some c la y s p e c ie s can e x i s t in u n s tr u c tu r e d fo rm , such as s e p i o l l t e o r p a ly g o r s k lte , and th e y may be p r e s e n t. But s in c e th e s e w ould c e r t a i n l y be amorphous t o X -ray s no in d ic a tio n o f t h e i r p re se n c e w ould b e re c o rd e d on th e d if f r a c to m e te r t r a c e . P h y s ic a l R e la tio n s h ip s The e r r a t i c n a tu r e o f th e p o re w a te r d a ta n o t o n ly mask th e ch em ical r e l a t io n s h i p s by o b s c u rin g p o s s ib le tr e n d s and p ro v id in g 157 s c a t t e r a t a l l l e v e l s , b u t s u g g e s ts , alm o st by d e f a u l t , t h a t a n o th e r p ro c e s s o r c o n tr o l msy be in f lu e n c in g th e v a rio u s c o n c e n tr a tio n s . S p e c i f i c a l l y , i t i s n o t b e lie v e d t h a t ch em ical r e a c tio n s co u ld acco u n t f o r th e o b se rv e d p r o fu s io n o f " n o is e " and th u s a n o th e r means o f re g u l a t i o n m ust be fo u n d . Membrane e f f e c t s v e r e d is c u s s e d i n t h i s r e g a rd i n th e c h l o r i n l t y s e c tio n . To re v ie w b r i e f l y from S ie v e r a l . (1 9 6 5 ), c la y s may " f i l t e r " th e i n t e r s t i t i a l w a te r su ch t h a t d u rin g co m p actio n f r e s h e r w a te r moves upw ard; th e e f f e c t can v a ry in i n t e n s i t y d ep en d in g on l o c a l p e r m e a b ility an d , c r u d e ly , g r a in s iz e o r p e r c e n t c la y . The d if f u s io n * “6 2 c o e f f i c i e n t f o r Cl” d e te rm in e d by K u lle n b e rg was 2 x 10” cm /s e c and th u s i n a re a s w ith h ig h s e d im e n ta tio n r a t e s , su ch as th e b a s in s s tu d i e d , th e somewhat subdued s ig n a tu r e o f a n c ie n t se a w a te r may rem ain f o r s e v e r a l th o u sa n d y e a r s . B ern e r (1971) s t a t e s t h a t Na+ has a d i f f u s io n c o e f f i c i e n t o f th e same o rd e r o f m ag n itu d e and th u s th e r e may be a s tr o n g d e g re e o f lik e lih o o d t h a t a l l o f th e m a jo r Io n s i n s o lu t i o n may r e f l e c t t o some e x t e n t , t h e i r p a s t c o n c e n tr a tio n s . As an ex am p le, i f we may ap p ly K u lle n b e rg 's e x p e rim e n ta lly d e riv e d d i f f u - * “6 2 s io n c o e f f i c i e n t f o r Cl” (2 x 10 cm / s e c ) t o th e S a n ta Cruz B asin o s e d im e n ts , w ith a r a t e o f d e p o s itio n o f 32 mg/cm /y e a r (Em ery, I9 6 0 ) we d is c o v e r t h a t th e s e d im e n ta tio n r a t e i s e q u iv a le n t t o d i f f u s io n r a t e b e c a u se th e y a r e o f th e same o rd e r o f m ag n itu d e , and p e r io d o f r a p id d e p o s itio n ( e . g . , t u r b i d i t y d e p o s it s , I n f lu x o f f lo o d se d im e n ts) may c o n tr ib u te sed im en t a t a g r e a t e r r a t e th a n th e c h lo r id e c o u ld move th ro u g h I t . In f a c t , tim e s o f anom alously r a p id d e p o s itio n can le a d t o u n d erco m p actio n o f th e s e d im e n t. T h is s i t u a t i o n i s p r e s e n t 158 in th e B o rd e rla n d ( Donn S. Q o r s lin e , p e r s o n a l com m unlcation) . T h u s» th e w a te r flo w due t o d i f f u s io n and co m p actio n may n o t h e k e e p in g p ace w ith sed im en t I n f l u x . T h is l a s t c irc u m sta n c e w ould have an unknown e f f e c t on th e p r e s e n ta tio n o f a n c ie n t s a l i n i t i e s . W hatever th e e x a c t c a s e , in a d e q u a c ie s do e x i s t i n h o th th e mem b ra n e and p a le o B a lin ity p o s s i b i l i t i e s . N am ely, i t i s b e lie v e d th e y c o u ld n o t e x p la in a l l o f th e v a r i a t i o n o b s e rv e d . C om putations by S ie v e r elt a l . (1965) showed t h a t t h e o v erb u rd en p r e s s u r e needed t o a c h ie v e th e membrane e f f e c t i s e q u iv a le n t t o a sed im en t th ic k n e s s o f a p p ro x im a te ly 100 m, a lth o u g h th e y p o in t o u t t h a t sed im en t may be more com pact even a t th e B u rface th a n h as been p r e d ic te d by t h e o r e t i c a l c o n s id e r a tio n s . In a d d i t i o n , th e e f f i c i e n c y o f a membrane f i l t r a t i o n i s u n d o u b te d ly enhanced by th e n e g a tiv e c h a rg e o f C l” (W h ite , 19610, b o t h a t t h i s Io n may m a n ife s t th e e f f e c t more th a n any o th e r Io n . I t a p p e a rs , t h e r e f o r e , t h a t even th ough Cl” shows a te n d e n c y t o in c r e a s e w ith d e p th , th e a c tio n o f a membrane system w ould e x e r t a m inim al e f f e c t on th e io n ic c o n c e n tr a tio n . Where a membrane e f f e c t may be p r e s e n t , how ever, i s i n th e a c tu a l sq u e e z in g o f th e se d im e n ts t o ex t r a c t th e p o re w a te rs (P a ra s h iv a M urthy and F e r r e l , 1 9 7 2 ). P a r t i c u l a r l y when a w a te r c o n te n t o f 30# i s a t t a i n e d i n th e se d im e n ts th e Donnan e f f e c t may ap p ly i f th e p r e s s u r e i s to o g r e a t . D is to r tio n o f t h i s n a tu r e i s im p ro b ab le in t h i s s tu d y . P a s sin g f r e s h e r w a te r th ro u g h w ould a llo w c o n c e n tr a tio n t o d e c re a s e o n ly . Even th e e v e n tu a l e x p e l l i n g o f more s a l i n e w a te r c o u ld o n ly te n d t o r e tu r n th e c o n c e n tr a tio n t o a m ore norm al l e v e l . 159 E n c o u n te re d d i f f i c u l t i e s w ith a p a l e o s a l i n l t y i n t e r p r e t a t i o n in c lu d e ra n g e e f f e c t s and sm o o th in g e f f e c t s * B ased on th e c h l o r l n i - t l e s d e te rm in e d i n t h i s s tu d y , e a l l n i t l e a w ould hav e had to ra n g e from 3 2 .5 o /o o to 39 o /o o . And ev en th o u g h th e tr e n d s p a r a l l e l th e m se lv e s to a h ig h d e g r e e , th e v a r i a t i o n s e n c o u n te re d w ith in 50 cm i n t e r v a l a r e u n r e a l i s t i c w ith r e g a rd to a s a l i n i t y change e x p la n a tio n , e s p e c i a l l y o v e r a p e r io d o f tim e o f th e o r d e r o f 1000 y e a r s . I f s a l i n i t i e s w ere m ark ed ly d i f f e r e n t in th e r e c e n t p a s t ( l e s s th a n 1 5 ,0 0 0 y e a r s B .P .) th e y p ro b a b ly w ere much lo w e r. R e s t r i c t e d b a s in s s u b je c te d t o p ro b a b ly h ig h e r r a i n f a l l and g r e a t e r r u n o f f c o u p le d w ith th e change o f ground w a te r e f f lu e n c e i n t o th e d e e p e r p o r tio n s o f th e b a s in makes t h i s c irc u m s ta n c e p o s s ib le in d e e d . T h u s, i t may be t h a t a lo w er s a l i n i t y c o u ld b e a c c o u n te d f o r , b u t th e h ig h e r o n es c a n n o t be ex p la in e d i n t h i s f a s h io n . Even i f m ajo r v a r i a t i o n s d id e x i s t , th e e x tre m e s w ould c e r t a i n l y b e b l o t t e d o u t by sm o o th in g e f f e c t s . D if f u s io n w i l l o c c u r to w ard any d i s p a r i t y o f c o n c e n tr a tio n , and s in c e s e d im e n ta tio n r a t e s a r e s i m i l a r t o d i f f u s i o n r a t e s any d is c re p a n c y w ould b e g in to u n d erg o c o m p en satio n a lm o st im m e d ia te ly . S o , w h ile s a l i n i t i e s in d ig e n o u s to p a s t c o n d itio n s may in p a r t be p r e s e r v e d , i t i s th e jud g em en t o f t h i s w r i t e r t h a t p r e s e n t p o re w a te r s show to o g r e a t a v a r i a t i o n and a r e to o a b r u p t in th e ch an g es in io n c o n c e n tr a t i o n t o be a c c o u n te d f o r by t h i s m eans a lo n e . S in c e n e i t h e r membrane e f f e c t s o r p a l e o s a l l n i t l e s c an a d e q u a te ly r e s o lv e th e p ro b le m , a s o lu t i o n m ust be found e ls e w h e re . T a b le V shows th e c o r r e l a t i o n s b etw een mean g r a in s i s e and th e v a r io u s io n i c s p e c i e s . The c o r r e l a t i o n c o e f f i c i e n t s a r e th e P e a rso n r ; th e te c h n iq u e s i6 o TABLE V C o r r e la tio n s b etw een p o re w a te r s p e c ie s c o n c e n tr a tio n and mean g r a in s i z e . CORRELATlOr SPECIES_________ d f________COEFFTCIEHT_______LEVEL OF SIQMIFICAMCE M g+2 1* 8 - 0 .7 3 99$ K* 1* 8 - 0 .5 3 99$ Ca+2 U8 - 0 .5 1 97$ S i0 2(Aq) U B - 0 *31 93% C l” 1 * 1 * - 0 .3 1 95$ Na+ 1 * 8 - 0 .1 7 75$ l 6 l u se d t o d e te m in e th e l e v e l o f s ig n if ic a n c e v e r e th o s e p u b lis h e d by S o k al and R o h lf (1969 ) . In e v e ry c a s e , a n e g a tiv e c o r r e l a t i o n i s o b s e rv e d , i n d ic a tin g t h a t f i n e r g r a in s iz e b e g e ts h ig h e r c o n c e n tra t i o n s o f io n s i n th e a s s o c ia te d w a te r s . The f a c t t h a t t h i s r e l a t i o n s h ip i s p r e s e n t f o r a l l io n s i s s u g g e s tiv e i n i t s e l f t h a t a cau se and e f f e c t r e l a t i o n s h i p e x i s t s . But w ith o u t a know ledge o f s i g n i f i cance o f t r e n d s , c o n c re te s ta te m e n ts a r e n o t w a rra n te d . A c c o rd in g ly , T a b le V a ls o shews th e l e v e l o f s ig n i f i c a n c e . F or th r e e o f th e io n s th e r e i s a 99# p r o b a b i li t y t h a t th e tre n d s a r e r e a l , and a l l b u t Na+ a re above 95#* T h u s, th e i n t e r s t i t i a l w a te r c o m p o sitio n , aB d e te r m ined i n t h i s s tu d y , may be in flu e n c e d by g r a in s i z e o r some r e l a t e d p a ra m e te r. S u b s ta n tia tio n from a n o th e r n e a rs h o re a r e a may b e g a in e d from th e d a ta o f H u lb e rt and G iv er ( in p r e p a r a t i o n ) . A c o r r e l a t i o n c o e f f i c i e n t d e te rm in e d f o r p e r c e n t c la y on Cl~ i s n e g a tiv e and s i m i l a r i n m agnitude t o th e a p p r o p r ia te c o e f f i c i e n t o f t h i s s tu d y ( - 0 .3 1 ) , a lth o u g h p erfo rm ed on ab o u t 20 few er sam p les. W e m ust now a d d re ss o u rs e lv e s t o a p o s s ib le re a s o n f o r a s s o c ia t i o n . I n t e r p r e t a t i o n w ith th e assu m p tio n t h a t th e e x p la n a tio n Bought need o n ly to a c c o u n t f o r th e m in o rity o f o b se rv e d v a r i a t i o n ( i . e . , c o r r e l a t i o n c o e f f i c i e n t s a r e n o t h ig h enough t o s u g g e s t t h a t th e m a jo r ity o f v a r i a t i o n i s r e l a t e d to g r a in s i z e ) , two p o s s i b i l i t i e s come f o r t h . One i s g r a in s iz e i t s e l f , a s i t i s r e l a t e d t o s u r f a c e a r e a s . As was o f f e r e d by B e rn e r (1971) in c r e a s e d s u r f a c e a r e a s can e x e r t a s tr o n g in f lu e n c e on th e v a r io u s io n s p r e s e n t i n th e p o re w a te r. They do so e s p e c i a l l y i n th e c o l l o i d s i z e ra n g e ( 1 m icro n ) w here th e s u r f a c e a r e a i s g r e a t com pared t o th e volum e. C o n tin u in g , 162 e l e c t r i c d o u b le - la y e r e f f e c t s become Im p o rta n t b e c a u se th e c h a rg e s on th e s u rf a c e may a t t r a c t o p p o s ite ly c h a rg e d Io n s ( c o u n te r io n s ) , lo n e o f d i f f e r e n t c h a rg e s , o r one l a y e r o f " o p p o s ite s " fo llo w e d by io n s w ith th e same ch arg e as th e o r i g i n a l s u r f a c e . The e f f e c t o f a l l t h i s w ould be t o d i s t i l l th e am b ien t p o re w a te rs i n p r o p o r tio n t o g r a in B ize. S in c e F le is c h e r (1970) h as shown t h a t up t o ap p ro x im a te ly 20% by w eig h t o f th e sed im en t i s o f c o l l o i d a l s i z e , i t I s c e r t a i n l y n o t beyond th e realm o f p o s s i b i l i t y t o e x p e c t in c r e a s e d c o n c e n tr a tio n s o f v a r io u s io n s a t le v e ls c o n ta in in g an abundance o f f i n e p a r t i c l e s . The +2 + +2 f a c t t h a t M g , K , and Ca have th e h ig h e s t c o r r e l a t i o n w ould s u i t t h i s p o s s i b i l i t y w e ll, s in c e th e y a re th e m ost s u e c e p ta b le t o s u rf a c e e f f e c t s (B e rn e r, 1971)* B ecause o f th e n e a r ly com plete o v e rla p o f t h i s e f f e c t w ith io n ex ch an g e, th e two may be c o n s id e re d e q u iv a le n t. I t h as been shown in T ab le V t h a t th e v a r i a t i o n i n m ost io n s w ould f i t , as o x id e s , w ith in th e ran g e d e te rm in e d by C lancy (1973) f o r th e exchange c a p a c ity v a r i a t i o n o f th e s e s e d im e n ts. Cl**, a lo n g w ith S i O g j ^ j , has th e n e x t h ig h e s t c o r r e l a t i o n and i s n o t a s in v o lv e d in +2 + +2 c a tio n exchange a s M g , K , and Ca . U ptake and r e le a s e o f s i l i c a by c la y s and o th e r s i l i c a t e s a ls o may w e ll be a f u n c tio n o f s u r f a c e a r e a , i n t h a t r e a c tio n s te n d t o be a c c e le r a te d as s u rf a c e a re a in c r e a s e s . I f s o , th e S i O ^ ^ j b e h a v io r co u ld a ls o be a c c o u n ted f o r in t h i s m anner. I t i s s i g n i f i c a n t i n l i g h t o f t h i s t h a t !fa+ i s th e o n ly c a tio n w hich can n o t be e x p la in e d by th e exchange c a p a c i t i e s and i t h a s th e lo w e s t c o r r e l a t i o n . O rg an ic m o le c u le s p r e v a le n t i n th e sed im en t may a f f e c t io n con c e n tr a tio n s as w e ll. T hese s u b s ta n c e s have a te n d en cy t o be p o la r and o f te n a d h e re t o c la y s u r f a c e s b e c a u se o f t h e i r l m n i s c i b l l l t y w ith w a te r and th e n a tu re o f t h e i r c h a rg e (Stumm and Morgan* 1 9 7 0 ). B ecause th e y d o n 't h av e an even d i s t r i b u t i o n o f c h a rg e , th e s e com plexes a t t r a c t b o th c a tio n s and a n io n s . The a s s o c ia tio n o f g r a in s iz e and q u a n tity o f o rg a n ic m a te r ia l h as b een docu m en tated by finery and R itte n - b e rg (1952) and Degens (1965)* A c o r r e l a t i o n c o e f f i c i e n t was d e t e r - m ined f o r M g on o rg a n ic c o n te n t (18 s a m p le s). The v a lu e was 0 . 26— & p o s i t i v e th o u g h weak a s s o c ia tio n w ith a c a lc u la te d s ig n if ic a n c e o f 70J(. ThiB i s n o t n e c e s s a r ily an im p lie d cau se and e f f e c t r e l a t i o n s h i p , s in c e o rg a n ic c o n te n t and g r a in s iz e a r e r e l a t e d and t h i s v a lu e may sim p ly r e f l e c t t h i s c o n n e c tio n r a t h e r th a n th e o rg a n ic o n e. Unknown r e l a t io n s h i p s e x i s t b etw een Na+ , Cl” , and ®*°2(Aq) and o r 6 ftnic m a te r ia l t o d a t e , a lth o u g h th e s e s p e c ie s may w e ll be a f f e c t e d by o rg a n ic m a te r ia lB . A ssem bling th e s e com m ents, i t seems l i k e l y t h a t exchange capa c i t i e s can encom pass t h e o b se rv e d sp ectru m o f change o f m ost o f th e io n s s tu d ie d . The in c r e a s e d s u r f a c e a r e a s , as r e l a t e d t o g r a in s i z e , may p la y a s i g n i f i c a n t r o le i n c o n tr o llin g io n c o n c e n tr a tio n s in i n t e r s t i t i a l w a te r s . An a s s i s t from c e r t a i n o rg a n ic m o le cu le s i s p o s s ib le a s w e ll. I n a b i l i t y t o a d e q u a te ly ac c o u n t f o r th e b e h a v io r Ma+ , and th e l e s s c e r t a i n in v o lv em en t o f Cl” and S iO g ^ ^ j sh o u ld b e n o te d a g a in . SUMMARY AND CONCLUSIONS D e fin in g ch em ica l a c t i v i t y In th e S o u th e rn C a lif o r n ia C o n tin e n ta l B o rd e rla n d sed im en ts I s an awkward ta s k w ith o u t know ledge o f th e e n t i r e se d im e n ta ry sy stem . T h ere a r e a m u ltitu d e o f f a c t o r s w hich can i n f l u ence p o re w a te r c h e m is try , o f w hich th e exam ple o f r e a c tio n w ith c la y s i s o n ly one. T h e re fo re th e v a rio u s c h e m ic a l, p h y s ic a l, and b i o l o g i c a l f a c t o r s and I n te r a c t i o n s m ust be com pensated f o r p r i o r t o I n te r p r e t a t i o n . One o f th e u n f o rtu n a te b y p ro d u c ts o f t h i s p ro fu s io n o f a c t i v i t y i s t h a t th e in d iv id u a l r e a c tio n s and p ro c e s s e s a r e d w arfed by th e mag n itu d e o f th e w hole. N o n e th e le s s , th e f e a s i b i l i t y o f c e r t a i n e v e n ts can be d e m o n stra te d . +2 U ptake o f Mg by th e c la y s i s a d e f i n i t e p o s s i b i l i t y . T h is i s shown b e s t in th e u p p er m e te r o f th e c o re w here d e p o s itlo n a l r a t e s have b een slo w e r th a n i n th e tim e i n t e r v a l b e fo re t h a t . A ls o , th e mode o f d e p o s itio n has b een l e s s s p o ra d ic and th e sed im e n ts have b een m ore u n ifo rm i n c o m p o sitio n i n th e more r e c e n t p a s t . No ev id e n c e i s s e e n t o s u g g e st t h a t M g i s r e p la c in g i r o n in th e c la y s (D rev er M odel) o r t h a t M g i s e n te r in g exchange s i t e s f r e e d by th e d i s s o l u t i o n o f an f e r r i c o x id e c o a tin g S h o lk o v itz M odel). Those m odels w ere a p p lie d t o re d u c in g e n v iro n m e n ts, h o w ev er, and b e ca u se th e re d o x s t a t e o f th e se d im en ts i n t h i s s tu d y i s n o t f ir m ly known, th e f in d in g s o f t h i s i n v e s t i g a t o r a r e n o t c o n s id e re d s e r io u s ly in ju r io u s t o th o s e two m o d els. 16k 165 I n sum, I f M g I s b e in g rem oved, i t i s b e in g f ix e d on exchange s i t e s o f c la y s . S im ila r c o n c lu s io n s w ere re a c h e d re g a rd in g th e K+ - K^O sy ste m , a lth o u g h w ith l e s s c o n fid e n c e , 1 < + shows no p r e f e r r e d change i n con c e n t r a t i o n w ith d e p th and th e KgO in c r e a s e down th e c o re s may be a c c o u n te d f o r by changes I n r e l a t i v e m in e ra l ab u n d an ce. The e n r ic h m ent o f K* i n th e i n t e r s t i t i a l w a te rs com pared t o b o tto m w a te r im p lie s r e l e a s e , p o s s ib ly by K -fe ld s p a r. S im u lta n e o u s ly , u p ta k e o f K + may b e o c c u rrin g i n th e u p p e r m e te r. Em ploying a r e l e a s e and rem o v al m echanism i n th e same en v iro n m e n t seems J u s t i f i e d , b u t i t i s r e i t e r a te d t h a t no i r r e f u t a b l e e v id e n c e was o b ta in e d t o s u b s t a n t i a t e e i t h e r c la im . The co n d u c t o f Na i s th e m ost d i f f i c u l t t o e v a lu a te . N e ith e r p o re w a te r d a ta o r b u lk c h e m istry d a ta e x h ib ite d a ten d en cy to w ard e n ric h m e n t o r d e p le tio n . C o n s is te n t d e c re a se o f Na* c o n c e n tr a tio n in t h e to p 50 cm may I n d ic a te t h a t c la y s may be w ith d ra w in g t h i s io n , b u t th e r e i s to o much s c a t t e r t o o f f e r even t h i s a s more th a n a teih- t a t i v e p o s s i b i l i t y . +2 A lthough th e e le m e n ts o f th e Ca - CaO system w ere a n a ly z e d , th e abundance o f c a rb o n a te s in th e s e se d im e n ts p re c lu d e d th e u se o f CaO d a ta t o I n t e r p r e t c la y m in e ra l d ia g e n e s is . H ie Ca tr e n d s w ere i n c o n s i s t e n t y e t i n i t i a l d i s s o l u t i o n o f c a rb o n a te s fo llo w e d by e n tr a p m ent i n th e o r g a n ic - r e s e r v o ir may b e h a p p e n in g . Amorphous a lu m in o s illc a te p e rc e n ta g e in c r e a s e s w ith d e p th below t h e se d im e n t-w a te r i n t e r f a c e i n th e two b a s in s w ith th e s lo w e s t r a t e o f d e p o s itio n and rem a in s unchanged i n th e t h i r d b a s in i n w hich a e d i- 166 m e n ta tio n r a t e l e f a r t e r . Amorphous s i l i c a , assum ed t o r e p r e s e n t th e q u a n tity o f s il i c e o u s o rg a n ism s, m irro s th e A l - s i l i c a t e p r o f i l e s . T h is may he e x p la in e d by d e p o s itio n o f more amorphous A l - s i l l c a t e m a te r ia l d u rin g th e p e r io d o f more I n te n s e ch e m ica l v e a th e r in g a s s o c ia te d w ith th e l a s t p l u v i a l p e r io d (c a . 12 ,0 0 0 t o 8 ,0 0 0 y e a rs B .P .) o r by d e e p e r e r o s io n i n t h a t p e r io d rem oving m a te r ia l from th e s o i l zone o f p r e c i p i t a t i o n . In c re a s e d d e t r l t a l s e d im e n ta tio n r a t e s d u rin g th e low s ta n d o f th e s e a w ould a ls o d i l u t e th e b io g e n ic com ponent. The c o n s ta n t h ig h r a t e o f d e p o s itio n i n th e t h i r d b a s in (S a n ta C ruz) p r e v e n te d sam p lin g a t s im i l a r tim e h o riz o n s so t h a t th e e f f e c t i s n o t m a n ife s te d t h e r e . Thus b o th s e t s o f tre n d s may be e x p la in e d by p ro c e s s e s u n r e la te d t o d la g e n e B is . F u r th e r , a c c o rd in g t o th e G a rre ls and M ackenzie m odel (1 9 6 6 ), amorphous A l - s l l i c a t e s h o u ld d e c r e a s e , n o t In c re a s e down th e c o r e s . I t i s s u g g e s te d , t h e r e f o r e , t h a t th e amorphous m a te r ia l i n th e B o rd e rla n d se d im e n ts i s n o t In v o lv e d in d ia g e n e tic r e a c t i o n s . The en ric h m en t o f S i O ^ j ^ j i n th e p o re w a te r c a n n o t, w ith c o n fid e n c e , be a t t r i b u t e d t o r e le a s e by c la y s o r b io lo g i c a l in p u t. B oth a re c a p a b le o f a c c o u n tin g f o r th e I n c r e a s e observed* No e v id e n c e f o r s t r u c t u r a l changes i n th e c la y s was n o te d , In d ic a tin g a p a u c ity o f d ia g e n e tic change i n t h i s a s p e c t o f th e in v e s t i g a t i o n , as w e ll. The o n ly e sc a p e from t h i s p re d ic a m e n t w ith r e g a rd to d e m o n stra tin g d ia g e n e s is l i e s i n th e X -ray amorphous component and H a llo y s ite . S e p i o l i t e and P a ly g o r s k lte can be am orphous t o X -ra y s , b u t , a s was co n clu d ed ab o v e, am orphous A l - s l l i c a t e p e rc e n ta g e does n o t d e c re a s e down th e c o re s as i t s h o u ld i f b e in g tra n s fo rm e d i n t o an a u th ig e n ic c la y . The p o s s i b i l i t y o f an amorphous a l u m l n o s i l l c a t e - - 167 H a llo y s i t e — Kao U n i t e continuum ) e x i s t s . However, a p p r o p r ia te changes In th e r e l a t i v e q u a n t i t i e s o f th e s e t h r e e p h a se s I s n o t a p p a r e n t, m aking t h i s s e r i e s d o u b tfu l as a h a rb o r f o r d la g e n e s ls . T h e re fo re , th e o n ly e v id e n c e f o r d la g e n e s ls o f c la y s was on th e exchange s i t e s ; s t r u c t u r a l changes and i n c i p i e n t c la y p h a se s a re n o t p r e s e n t i n th e s e se d im e n ts a t l e a s t t o th e l e v e l o f d e te c tio n em ployed i n t h i s in v e s t i g a t i o n . V a c illa tio n s in d is s o lv e d s p e c ie s abundance may be a t t r i b u t e d t o p ro c e s s e s o th e r th a n B tr a ig h t d la g e n e s ls . Membrane e f f e c t s , s p ik in g by a n c ie n t se a w a te r r e s i d u e , g r a in s iz e (a s r e l a t e d t o s u r f a c e a r e a s ) and c e r t a i n o rg a n ic m o le c u le s may a l l e x e r t an In flu e n c e on th e i n t e r s t i t i a l w a te r c h e m is try , w ith g r a in s iz e b e in g th e m ost Im p o rta n t. T h is i s p a r t i c u l a r l y t r u e o f c o n tin e n ta l m arg in a re a s w here d e p o s i t i o n ra te B a re h ig h , v a r i a b l e , and e p is o d ic , and w here o r g a n ic - r ic h sed im e n ts a re comnon. H eath ( in p r e s s ) su b m its t h a t t h i s ty p e o f a r e a may w e ll in d e e d be th e env iro n m en t o f r a p id rem oval o f io n s from s o lu t i o n , b u t , as he a ls o s t a t e s , th e e f f e c t s may b e so d i l u t e d t h a t th e y w ould e sc a p e d e te c tio n . In c o n ju n c tio n w ith t h i s , Manheim and S ay le3 ( i n p r e s s ) c h a r a c te r iz e n e a rs h o re a re a s as show ing c o n s id e r a b le v a r i a t i o n in p o re w a te r c o m p o sitio n . These two s ta te m e n ts a re a c c o rd a n t w ith th e f in d in g s o f t h i s s tu d y . I t i s co n clu d ed t h a t c o n tin e n ta l m arg in sed im en ts o f t h i s ty p e a re n o t i n c h e m ic al e q u il ib riu m w ith th e su rro u n d in g i n t e r s t i t i a l w a te r s . A c c o rd in g ly , th e p r e v io u s ly m en tio n ed im p lic a tio n s w ith re g a rd t o ch em ical e q u ilib riu m ( O a rr e ls and M ackenzie, 1971) a re n o t s u p p o rte d by t h i s s tu d y . 160 F i n a l l y , I t i s hoped t h a t th e d a n g e rs o f I n t e r p r e t i n g d ia g e n e tic p ro c e s s e s from o n ly one l i n e o f e v id e n c e i s u n d e rsc o re d . C hem ical and p h y s ic a l v a r i a t i o n s e n c o u n te re d i n th e en v iro n m en t o f t h i s stu d y make a v a l i d d e f i n i t i o n o f th e p ro c e s s e s In v o lv e d an ard u o u s and d e l i c a t e t a s k , d e s p ite th e th o ro u g h e x a m in a tio n r e p o r te d h e r e . REFERENCES 169 REFERENCES A l l , S. A ., G riedm an, G. M ., an d A m iel, A. J . , 19 7 2 , C hem ical com- p o a i t l o n o f I n t e r s t i t i a l w a te r s from m arin e s e d im e n ts , B a f f in Bay: J o u r . S ed . P e tr o lo g y , v . 1*2, p . 79l*-802. B en-Y aakov, S . , 19 7 2 , D if f u s io n o f s e a w a te r io n s — I . D if f u s io n o f Bea w a te r i n t o a d i l u t e s o lu t i o n : Qeochim . e t Cosmochim. A c ta , v . 3 6 , p . 1395-1**06. B e r n e r , R. A ., 1 9 7 0 , S e d im e n ta ry p y r i t e fo rm a tio n : Am. J o u r . 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L . , an d Ku, T . , 1 9 7 0 , P o re f l u i d s o f r e c e n t m a rin e s e d im e n ts : I . , o x id iz in g se d im e n ts o f 2 0 ° N ., c o n t i n e n t a l r i s e t o M id -A tla n tic R id g e: J o u r . S ed. P e tr o lo g y , v . 1*0, n . 3 , p . 9 6 0 -9 7 2 . B is c h o f f , J . L . , and Ku, T . , 1 9 7 1 , P o re f l u i d s o f r e c e n t m arin e s e d im e n ts : l i . , A noxic s e d im e n ts o f 35° t o 1*5° N G i b r a l t a r t o M id - A tla n tic R id g e: J o u r . S ed . P e tr o lo g y , v . 1*1, p . 10 0 8 -1 0 1 8 . B is c h o f f , J . L . , an d S a y le s , F . L . , 19 7 2 , P o re f l u i d and m in e ra lo g i e s ! s t u d i e s o f r e c e n t m arin e s e d im e n ts : B au er D e p re ssio n R egion o f E a s t P a c i f i c R is e : J o u r . S ed. P e tr o lo g y , v . 1*2, p . 711-721*. B r in d le y , G. 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Creator Booth, James Storms (author)

Core Title Early Diagenesis In Southern California Continental Borderland Sediments

Degree Doctor of Philosophy

Degree Program Geological Sciences

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

Tag Geology,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Gorsline, Donn S. (committee chair), Bischoff, James L. (committee member), Osborne, Robert H. (committee member), Reaves, Gibson (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c18-670784

Unique identifier UC11355800

Identifier 7414427.pdf (filename),usctheses-c18-670784 (legacy record id)

Legacy Identifier 7414427.pdf

Dmrecord 670784

Document Type Dissertation

Rights Booth, James Storms

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