Research Products:

• View a UNRSL Colloquium presentation Feb. 17 1998 describing the shallow geophysical character of Amargosa and Chicago Valleys, and resulting tectonic constraints.

• View a paper describing the shallow geophysical character of the southern Pahrump Valley fault zone, published in the Bulletin of the Seismological Society of America.

• View a paper on the shallow and mid-crustal velocity structure of the Death Valley region, and its constraints on Cenozoic extension models, published in Geophysical Research Letters.

• View a paper on prestack migration imaging of a fault plane in southern Death Valley, published in Geophysics.

• View Sergio Chavez-Perez's 1997 UNR Ph.D. Thesis ``Enhanced Imaging of Fault Zones in Southern California From Seismic ReflectionStudies''

• Analysis of the Pahrump Valley fault zone in Stewart Valley and southern Pahrump Valley, establishing a 0.1 mm/yr minimum displacement rate, as:
  • Manuscript accepted by the Utah Geological Survey for publication in the Proceedings of the Basin and Range Province Seismic Hazards SummitMay 12-15, 1997, Reno, Nevada, (HTML, or Adobe Acrobat PDF)
  • Presentation at the Seismic Hazards in the Las Vegas Region conference, Nov. 15, 1996, UNLV
  • Manuscript for submittal to the conference proceedings to be published by the Assoc. Engineering Geol., Southwest Section (HTML with 282 kb of images, or 2.1 Mb Adobe Acrobat PDF)
  • Poster presented at 1996 Fall American Geophysical Union meeting, Dec. 17, San Francisco

• View the expanded abstract of a presentation on prestack migration imaging of a fault plane in southern Death Valley, made at the 1996 Society of Exploration Geophysicists Annual International Meeting, Denver.

• View a paper on the structure and tectonic history of Tecopa Valley, submitted to a Geological Society of America Special Paper on Cenozoic Basins of the Death Valley Region.

• View the abstract of a poster on regional Pg tomography results, presented at the 1995 American Geophysical Union Fall Meeting, San Francisco.

• View a poster showing strike-slip fault detection with geophysical methods, presented at the 1994 American Geophysical Union Fall Meeting, San Francisco.

  NSF Geophysics Proposal, 1 June 1996

  • Geophysical constraints on Tertiary and Quaternary tectonics between Death Valley, Calif. and Las Vegas, Nevada

• Working list of data and analyses, for internal use.

PROJECT SUMMARY

Regional tectonic models suggest the mode and timing of the development of several small sedimentary basins east of Death Valley, California. Although hidden, the stratigraphy of each basin may be diagnostic of the mode and timing of extension. Three years of geophysical field course exercises out of the Penn State University and the University of Nevada, Reno; conducted by Dr. Louie in the Amargosa and Chicago Valleys have revealed early basin histories and distinct formational geometries. The use of several small-scale survey methods on the same profiles resulted in sufficient structural and stratigraphic control to date initial basin formation and describe a major boundary in regional extensional character.

Datasets on a regional scale provide additional constraints on tectonic models. A non-linear inversion of first-arrival travel time picks from the extensive COCORP Death Valley lines 9 and 10, combined with regional surface wave group arrival times, show few differences in overall crustal velocity structure when comparing the southern Great Basin with surrounding tectonic provinces. This observation suggests broadly similar crustal histories despite great differences among the provinces in the amounts of Cenozoic extension interpreted. This project will continue this analysis by developing constrained velocity models from all available regional seismic survey and earthquake travel-time data. It will also provide for the reprocessing of the COCORP lines for shallow basin structure, to extend features surveyed in detail to wider regions; and evaluate seismic data for fault reflections and constraints on fault geometries.

The proposed further small-scale efforts will characterize the Tecopa and Chicago Valley basins in three dimensions, and will extend basin analysis east across Pahrump Valley to the Spring Mountains. This project will continue these efforts as yearly geophysical field course exercises, involving students of diverse backgrounds in a project each carries from the planning through the reporting stages. Constrained by mid- and upper-crustal characterizations of velocity structure, these results will test the geophysical and sedimentary features proposed by differing Cenozoic tectonic models.