Academic Journal
Internal Structure and Weakening Mechanisms of the San Andreas Fault
| العنوان: | Internal Structure and Weakening Mechanisms of the San Andreas Fault |
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| المؤلفون: | Chester, Frederick M., Evans, James P., Biegel, Ronald L. |
| المساهمون: | American Geophysical Union |
| المصدر: | Geosciences Faculty Publications |
| بيانات النشر: | Hosted by Utah State University Libraries |
| سنة النشر: | 1993 |
| المجموعة: | Utah State University: DigitalCommons@USU |
| مصطلحات موضوعية: | internal structure, weakening mechanisms, San Andreas fault, Earth Sciences, Geology, Physical Sciences and Mathematics |
| الوصف: | New observations of the internal structure of the San Gabriel fault (SGF) are combined with previous characterizations of the Punchbowl fault (PF) to evaluate possible explanations for the low frictional strength and seismic characteristics of the San Andreas fault (SAF). The SGF and PF are ancient, large-displacement faults of the SAF system exhumed to depths of 2 to 5 km. These fault zones are internally zoned; the majority of slip was confined to the cores of principal faults, which typically consist of a narrow layer (less than tens of centimeters) of ultracataclasite within a zone of foliated cataclasite several meters thick. Each fault core is bounded by a zone of damaged host rock of the order of 100 m thick. Orientations of subsidiary faults and other fabric elements imply that (1) the maximum principal stress was oriented at large angles to principal fault planes, (2) strain was partitioned between simple shear in the fault cores and nearly fault-normal contraction in the damaged zones and surrounding host rock, and (3) the principal faults were weak. Microstructures and particle size distributions in the damaged zone of the SGF imply deformation was almost entirely cataclastic and can be modeled as constrained comminution. In contrast, cataclastic and fluid-assisted processes were significant in the cores of the faults as shown by pervasive syntectonic alteration of the host rock minerals to zeolites and clays and by folded, sheared, and attenuated cross-cutting veins of laumontite, albite, quartz, and calcite. Total volume of veins and neocrystallized material reaches 50% in the fault core, and vein structure implies episodic fracture and sealing with time-varying and anisotropic permeability in the fault zone. The structure of the ultracataclasite layer reflects extreme slip localization and probably repeated reworking by particulate flow at low effective stresses. The extreme slip localization reflects a mature internal fault structure resulting from a positive feedback between comminution and ... |
| نوع الوثيقة: | text |
| اللغة: | unknown |
| Relation: | https://digitalcommons.usu.edu/geology_facpub/42; https://doi.org/10.1029/92JB01866 |
| DOI: | 10.1029/92JB01866 |
| الاتاحة: | https://digitalcommons.usu.edu/geology_facpub/42 https://doi.org/10.1029/92JB01866 |
| Rights: | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact the Institutional Repository Librarian at digitalcommons@usu.edu. |
| رقم الانضمام: | edsbas.4BCC49FA |
| قاعدة البيانات: | BASE |
| DOI: | 10.1029/92JB01866 |
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