NSF EarthScope EAR-0454525: May 12, 2005 to May 11, 2007
Collaborative Research: Structural-Petrologic Characterization of the San Andreas Fault Zone in the SAFOD Drill Holes
J. S. Chester & F. M. Chester (Texas A&M University)
J. P. Evans (Utah State University) & D. L. Kirschner (Saint Louis University)
Teresa Sabato (TAMU), Rafael Almeida (TAMU)
Project Scope
In collaboration, Judith Chester and Frederick Chester of Texas A&M University, James Evans of Utah State University, and David Kirschner of Saint Louis University are analyzing the rock cuttings and cores from the main drillhole of SAFOD to characterize the composition, structure, and deformation mechanisms of the San Andreas fault zone. The work is addressing key questions regarding mineralogic transformations, fluid-rock interactions, physical properties, and mechanics of the fault, and is testing hypotheses of earthquake rupture dynamics, energy balance, and fault weakening.
Specific objectives include: 1) Determining the physical and chemical processes that operate at depth along the San Andreas fault zone to guide future experiments and modeling studies of earthquake mechanics. 2) Integrating this work with previous studies of seismogenic faults and with data derived from other SAFOD studies to develop a comprehensive model of the San Andreas fault zone. 3) Collaborating with others to develop an integrated fault-zone model that will help guide the SAFOD drilling team's decisions during Phase 3 coring of the fault in 2007. 4) In collaboration with others, defining future questions, goals, and analysis techniques to help formulate a core-handling plan for Phase 3 of the SAFOD project in 2007-2008.
Current work includes 1) making detailed wrap-around maps of the core at the mesoscopic scale, 2) determining timing, distribution and orientations of mesoscopic opening mode fractures and faults, veins, and other fabric elements, and using these data to determine the core orientation, 3) characterizing the microstructure, mineralogy, geochemistry and particle size distributions of the different fault rocks captured in the main core and side wall core samples.
Techniques being used to analyze the petrology and microstructure include XRD, optical microscopy, microprobe, and scanning and transmission electron microscopy. In addition, the major and minor element chemistry of all samples are being measured by ICP and/or XRF analyses. An aliquot of some samples are being sent to John Solum at the USGS for more detailed analyses of the clays, and another aliquot of most samples are being analyzed for their stable isotope geochemistry (oxygen, hydrogen, carbon).Masters Theses and Doctoral Dissertations
- Teresa Sabato Ceraldi (PhD Geology, in progress). SAFOD Research.
- Rafael Almeida (MS Geology, in progress). SAFOD Research.
Research Products
- Core box depth and length summary pdf
- Overview lithologic column for Phase I cores pdf
- Hickman, S., et al., Photographs and Scans of SAFOD Phase 2 Sidewall Cores, SAFOD Phase 2 Sample Party, USGS in Menlo Park, December 4, 2005 (updated 1-Oct.-2006). powerpoint (116 M)
- Wrap-Around Maps of the SAFOD Phases 1 and 2 Spot Cores: P1_core_map_1-9, P1_core_map_10-23, P2_core_map_1-4.
Abstracts and Oral Presentations
- Chester, J. S., et al., Overview of Mesoscale Structure and Lithology of the SAFOD Phase 1 and 2 Spot Core Samples, taken from presentations at SAFOD Workshops, IODP-GCR, spring 2005, and Menlo Park, fall 2005. (updated 13 Feb. 2006)
- Almeida, R., Chester, J. S., Chester, F. M., and Kirschner, D. L., Moore, D. E., and Waller, T. J., Mesoscale structure and lithology of the SAFOD phase I and II core samples, EOS Trans. AGU, T21A-0454, 86(52), 2005. abstract, poster
- Kirschner, D.L., Evans, J., Chester, J., Chester, F., Solum, J., Moore, D., Elemental and stable isotope chemistry of cuttings and core samples from SAFOD drill hole, EOS Trans. AGU, T21A-0452, 86(52), 2005. abstract, poster
