Evidence for fluid-assisted shear failure in a ductile shear zone: tectonic tremor in the geologic record?
| dc.contributor.author | Compton, Katharine, author | |
| dc.contributor.author | Kirkpatrick, James, advisor | |
| dc.contributor.author | Magloughlin, Jerry F., committee member | |
| dc.contributor.author | von Fischer, Joe, committee member | |
| dc.date.accessioned | 2015-08-28T14:35:18Z | |
| dc.date.available | 2015-08-28T14:35:18Z | |
| dc.date.issued | 2015 | |
| dc.description.abstract | Recent direct observations of tectonic tremor below the seismogenic zone of large fault zones have emphasized the significance of coeval ductile and brittle processes at high temperatures. Tectonic tremor is defined as long-duration, low-amplitude, and low-frequency seismic signals produced at depths of 18-40 km. Because the source of tremor is currently unknown, the physical conditions and processes that cause tremor are unknown. This study presents observations of an exhumed shear zone system contained within the Saddlebag Lake pendant of the eastern Sierra Nevada, California. The high-strain rocks in this shear zone exhibit multiple episodes of vein formation, indicating a prolonged migration of hydrothermal fluids through the system. Crosscutting relationships and mineral assemblages define discrete sets of variously oriented veins that are folded and boudinaged. I document foliation-parallel quartz veins that show shear displacement parallel to the foliation. Textural evidence for dynamic recrystallization mechanisms, stable isotope data, and fluid inclusion thermobarometry measurements indicate temperatures between 300-680°C and relatively high fluid pressure conditions, greater than σ₃, during fracture. Conditions of nucleation of shear fractures within this ductile shear zone suggest these structures may record similar processes to those under which tectonic tremor is observed in other continental transform fault zones. I interpret that these veins formed as shear fractures under increasing differential stress and fluctuations in pore pressure, with failure driven by heterogeneous materials within the shear zone. | |
| dc.format.medium | born digital | |
| dc.format.medium | masters theses | |
| dc.identifier | Compton_colostate_0053N_13123.pdf | |
| dc.identifier.uri | http://hdl.handle.net/10217/167150 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation.ispartof | 2000-2019 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.title | Evidence for fluid-assisted shear failure in a ductile shear zone: tectonic tremor in the geologic record? | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). | |
| thesis.degree.discipline | Geosciences | |
| thesis.degree.grantor | Colorado State University | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science (M.S.) |
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