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dc.contributor.authorFrancsis, Matthew Keeganen_US
dc.date.accessioned2014-03-14T20:34:58Z
dc.date.available2014-03-14T20:34:58Z
dc.date.issued2012-04-20en_US
dc.identifier.otheretd-05032012-162325en_US
dc.identifier.urihttp://hdl.handle.net/10919/32170
dc.description.abstractDynamically recrystallized quartz microstructure and grainsize evolution along mid-crustal shear zones allows for the estimation of tectonic driving stresses and strain rates acting in the mid-crust. Quartz-rich tectonites from three exhumed mid-crustal shear zones, the Main Central Thrust (MCT; Sutlej valley, NW India), South Tibetan Detachment System (STDS; Rongbuk valley, S Tibet), and Moine thrust (NW Scotland), were analyzed. Deformation temperatures estimated from quartz microstructural and petrofabric thermometers indicate steep apparent thermal gradients (80â 420 °C/km) across 0.5â 2.3 km thick sample transects across each shear zone. Quartz recrystallization microstructures evolve from transitional bulging/sub-grain rotation to dominant grain boundary migration at ~ 200 m structural distance as traced away from each shear zone. Optically measured quartz grainsizes increase from ~ 30 μm nearest the shear zones to 120+ μm at the largest structural distances. First-order Zener space analysis across the Moine nappe suggests strong phyllosilicate control on recrystallized quartz grainsize. Recrystallized quartz grainsize piezometry indicates that differential stress levels sharply decrease away from the shear zones from ~ 35 MPa to 10 MPa at ~ 200 m structural distance. Strain rates estimated with quartz dislocation creep flow laws are tectonically reasonable, between 10-12—10-14 s-1. Traced towards each shear zone strain rate estimates first decrease one order of magnitude before rapidly increasing one to two orders of magnitude at structural distances of ~ 200 m. This kinked strain rate profile is likely due to the steep apparent thermal gradients and relatively constant differential stress levels at large structural distances.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartFrancsis_MK_T_2012.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectMoine Thrusten_US
dc.subjectMain Central Thrusten_US
dc.subjectquartz piezometryen_US
dc.subjectflow lawen_US
dc.subjectGreater Himalayan Seriesen_US
dc.subjectSouth Tibetan Detachment Systemen_US
dc.titlePiezometry and Strain Rate Estimates Along Mid-Crustal Shear Zonesen_US
dc.typeThesisen_US
dc.contributor.departmentGeosciencesen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineGeosciencesen_US
dc.contributor.committeechairLaw, Richard D.en_US
dc.contributor.committeememberSpotila, James A.en_US
dc.contributor.committeememberCaddick, M. J.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05032012-162325/en_US
dc.date.sdate2012-05-03en_US
dc.date.rdate2012-05-21
dc.date.adate2012-05-21en_US


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