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FAULT ZONE STRUCTURE AND EVOLUTION AT CONTINENTAL PLATE BOUNDARIES by Whitney Maria Behr A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (GEOLOGICAL SCIENCES) August 2011 Copyright 2011 Whitney Maria Behr
|Title||Fault zone structure and evolution at continental plate boundaries|
|Author||Behr, Whitney Maria|
|Degree||Doctor of Philosophy|
|Degree program||Geological Sciences|
|School||College of Letters, Arts And Sciences|
|Advisor (committee chair)||Platt, John P.|
|Advisor (committee member)||
Davis, Gregory A.
Becker, Thorsten W.
Hudnut, Kenneth W.
Rechenmacher, Amy L.
|Abstract||Decades of research has illustrated that the continental lithosphere, particularly the crust within it, is compositionally evolved and heterogeneous. The compositional heterogeneity is clearly associated with rheological layering, yet the precise rheological behavior of each layer has proven difficult to quantify. In particular, two important questions have remained unresolved for several decades. 1) What is the integrated and peak strength of the continental lithosphere and where does the peak strength reside? 2) To what degree is deformation localized into faults and shear zones at different depths? A variety of sub-disciplines in the earth sciences, including geology, geodesy, and geophysics have focused on these issues for both modern and ancient continental orogens. In this thesis, I address these two questions, both directly and indirectly, but from two quite separate subdisciplines: active tectonics and structural geology. Chapter 2 focuses on whether discrepancies in geologic vs. geodetic slip rates are real, given the uncertainties in geologic slip rate estimates. In Chapters 3 and 4 the magnitude of stress within the middle and lower crust is quantified for two separate tectonic settings: the Whipple Mountains in eastern California (Chapter 3), representing post-collisional extension, and the Sierra Alhamilla in southern Spain (Chapter 4), representing syn-collisional extension. The stress profiles differ in detail, but lead to the same overarching conclusions: 1) the magnitude of stress at the brittle-ductile transition is high, consistent with the extrapolation of Byerlee’s law at hydrostatic pore fluid pressures; and 2) the decreases in stress with depth and the associated strain rates are consistent with weak quartzite flow laws, but inconsistent with strong ones. In Chapter 5 I show that measurements of dynamic stress from pseudotachylites, are within error of measurements of static stress from brittle-to-ductile shear zones, suggesting that the formation of melt along the fault may have triggered seismic arrest, rather than lubrication. Chapter 6 is a methods chapter demonstrating that NIST 6XX glass standards can be used to quantify the Ti contents of quartz if the matrix effect between these glasses and nearly pure quartz can be corrected.|
|Keyword||structural geology; paleopiezometry; metamorphic core complexes; san andreas fault; pseudotachylite; Ti-in-quartz thermobarometry|
|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|
|Legacy record ID||usctheses-m|
|Rights||Behr, Whitney Maria|
|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 author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given.|
|Repository name||University of Southern California Digital Library|
|Repository address||USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA|
|Full text||FAULT ZONE STRUCTURE AND EVOLUTION AT CONTINENTAL PLATE BOUNDARIES by Whitney Maria Behr A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (GEOLOGICAL SCIENCES) August 2011 Copyright 2011 Whitney Maria Behr|