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through those first few months of TAing, classes, and research without going crazy.
Kurt Frankel and Stephanie Briggs (technically UCLA, but we’ll let that slide), made
life on the Westside great fun. I certainly won’t forget our many bike rides (particularly
the “Three Bitches”!) and all the yummy breakfasts at Lazy Daisy. Other graduate
students that I have been fortunate to know during my time at USC include Özgür
Kozaci, Lorraine Leon, Plamen Ganev, Everett Salas, Iain Bailey, Michael Lewis,
Adam Fischer, David Farris, Vali Memeti, and Reetta Saikku.
As for Erik, well what can I say? Thanks for making the last four years in
LA both fun and fitness intensive (particularly on the bike!). Without you I seriously
wouldn’t have been able to complete the intense field work required of this project!
Thanks also for making sure that I take necessary breaks from work to relax and go
for our little walks around campus, otherwise I probably would have been glued to my
desk 24 hours a day.
I would like to thank the administration staff at USC: John McRaney, John Yu,
Cindy Waite, Vardui Ter-Simonian, and Karen Young. Without their tireless dedication
to making sure that we graduate students are looked after, we’d probably all be living
on the street while trying to finish our degrees!
Finally, I need to thank my parents, Sally Owen and Stephen Cooper, who have
supported me throughout my education, even when it has taken me so far away from
home. I miss them dearly, and hope that one day not too far off, I will be living a little
closer to them! In addition I would like to acknowledge my brother Jules, who I still
Object Description
| Title | Structural and thermobarometric constraints on the exhumation of the northern Snake Range metamorphic core complex, Nevada |
| Author | Cooper, Frances Jacqueline |
| Author email | fcooper@usc.edu; fcooper@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Geological Sciences |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-08-27 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-22 |
| Advisor (committee chair) | Platt, John P. |
| Advisor (committee member) |
Davis, Gregory A. Morrison, Jean Platzman, Ellen Thompson, Mark E. |
| Abstract | Observations from areas of large-scale continental extension, including the Basin and Range Province in western North America, have revealed the presence of regionally subhorizontal normal faults that appear to have exhumed rocks from mid- to lower-crustal levels. These detachment faults separate upper plate rocks extended on arrays of high-angle brittle normal faults from lower plate rocks exhibiting ductile mylonitic stretching and medium- to high-grade metamorphism. The origin and evolution of these detachments has been a matter of debate for decades, and yet a number of issues remain unresolved: (1) the dip of the faults when they were initiated and were active; (2) their penetration depth into the crust; (3) their role in exhuming high-grade metamorphic rocks; and (4) the origin and significance of the mylonitic deformation in their footwalls.; I explored these issues in the footwall to a classic detachment fault -- the northern Snake Range décollement (NSRD) in eastern Nevada -- using a combination of structural geology, geothermobarometry, paleomagnetism, isotope geochronology, and electron backscatter diffraction (EBSD) analysis. Garnet-biotite-muscovite-plagioclase thermobarometry suggests that the footwall to the NSRD experienced late Cretaceous peak metamorphic conditions of 6–8 kbar and 500–650°C, equivalent to a burial depth of ≤ 30 km. Calcite-dolomite thermometry indicates that Tertiary mylonitic deformation occurred under lower temperature conditions of 350–430°C, equivalent to mid-crustal levels. Structural, paleomagnetic, and EBSD data demonstrate that mylonites experienced two phases of shear (top-east and top-west), inconsistent with movement along a single throughgoing normal fault.; I conclude that exhumation of the northern Snake Range footwall was a two-step process. Initial ductile stretching and thinning of the crust exhumed footwall rocks to the middle crust beneath a discontinuity, referred to as the localized-distributed transition (LDT), that separated extension along brittle normal faults above from localized ductile shear zones below. Mylonites formed along the LDT were subsequently captured by a moderately-dipping NSRD that soled into the middle crust. The NSRD, therefore, appears to be a late-stage brittle normal fault that was responsible for only about half the total exhumation of the footwall, and is not directly related to the mylonitic deformation. |
| Keyword | continental extension; extensional tectonics; Basin and Range province; Cordillera; metamorphism; mylonite zone |
| Geographic subject | tectonic features: Snake Range décollement |
| Geographic subject (state) | Nevada |
| Geographic subject (country) | USA |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1695 |
| Contributing entity | University of Southern California |
| Rights | Cooper, Frances Jacqueline |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Cooper-2458 |
| Archival file | uscthesesreloadpub_Volume40/etd-Cooper-2458.pdf |
Description
| Title | Page 5 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | v through those first few months of TAing, classes, and research without going crazy. Kurt Frankel and Stephanie Briggs (technically UCLA, but we’ll let that slide), made life on the Westside great fun. I certainly won’t forget our many bike rides (particularly the “Three Bitches”!) and all the yummy breakfasts at Lazy Daisy. Other graduate students that I have been fortunate to know during my time at USC include Özgür Kozaci, Lorraine Leon, Plamen Ganev, Everett Salas, Iain Bailey, Michael Lewis, Adam Fischer, David Farris, Vali Memeti, and Reetta Saikku. As for Erik, well what can I say? Thanks for making the last four years in LA both fun and fitness intensive (particularly on the bike!). Without you I seriously wouldn’t have been able to complete the intense field work required of this project! Thanks also for making sure that I take necessary breaks from work to relax and go for our little walks around campus, otherwise I probably would have been glued to my desk 24 hours a day. I would like to thank the administration staff at USC: John McRaney, John Yu, Cindy Waite, Vardui Ter-Simonian, and Karen Young. Without their tireless dedication to making sure that we graduate students are looked after, we’d probably all be living on the street while trying to finish our degrees! Finally, I need to thank my parents, Sally Owen and Stephen Cooper, who have supported me throughout my education, even when it has taken me so far away from home. I miss them dearly, and hope that one day not too far off, I will be living a little closer to them! In addition I would like to acknowledge my brother Jules, who I still |
