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Reflection Seismology Program

Great Salt Lake



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Great Salt Lake Basin Evolution Study

gslgif4r.gif (22535 bytes)    Reprocessing and analysis of an extensive grid of industry "marine" seismic profiles from the Great Salt Lake obtained by the University of Arizona shows that the major basin-bounding normal faults beneath the lake are listric in nature (beginning at angles of ~60° near the surface, and soling out at depths of 5-7 km).  Although previously unrecognized, our interpretations of the seismic and available geologic data show that the trace of the Willard thrust lies beneath the Great Salt Lake and extends to the west from between Fremont and Antelope Islands to the eastern flank of Stansbury Island.  Structural relationships that we interpreted from Great Salt Lake seismic reflection data just northwest of Antelope Island suggest that major basin-bounding normal faults beneath the Great Salt Lake are controlled by normal-slip reactivation of older thrust faults.

    Recent work related to this project has concentrated on developing a program of relatively shallow (a few tens of meters up to ~1200 m) coring of rocks to constrain neotectonic deformation and seismic hazard, and provide for a continuous strati­graphic record for paleoclimatic and lake-chemistry studies with Andy Cohen, Owen Davis and Jay Quade.  To accomplish this, we proposed (with other scientists) to build a continuous coring rig that would be operated as a scientific facility by the DOSECC (Drilling Observation and Sampling of the Earth’s Continental Crust) consortium for lake drilling projects worldwide.  Two related proposals were successful, gaining support for the facility and GSL drilling from the National Science Foundation (NSF) and International Continental Drilling Program (ICDP) (Potsdam, Germany).  Drilling in the Great Salt Lake, which was completed in August and September 2000, is providing important new tectonic and climatic information and served as the first lake test of the new coring facility.  New information developed through this project will be integrated into the knowledge gained from our ongoing analyses of industry seismic and well data.

Some of the results from this project are published in the Journal of Geophysical Research (Mohapatra and Johnson, 1998, JGR, Vol. 103, B5, p. 10,047 - 10,063).