Abstract Title: Plans for a funded 250km wide-angle reflection/refraction study 
across the northwestern Basin and Range transition zone: to be acquired in 
September 2004

Abstract Author(s): Lerch, D.L. (Stanford University) Ð Colgan, J.C. (Stanford 
University) Ð Klemperer, S.L. (Stanford University) Ð Miller, E.L. (Stanford 
University) - Gashawbeza, E. (Stanford University)  

Abstract: Regional structural and thermochronologic studies across northwestern 
Nevada indicate the region underwent late (<10-11 Ma), low-magnitude (<15%) 
extension. This extension was minor compared to extension documented in parts 
of the Basin and Range to the south and east (50-100%). Despite relatively low 
supracrustal extension, the crust in northwestern Nevada appears to be among 
the thinnest in the Basin and Range, raising the possibility that the region 
underwent flow of a ductile middle or lower crust away from the area to more 
extended regions to the south. To investigate this hypothesis, NSF-EarthScope 
and ACS-Petroleum Research Fund have funded a 260km seismic 
refraction-reflection experiment in September 2004. The study will span 
northwestern Nevada and northeastern California, from the west side of the 
Santa Rosa Range to the Modoc Plateau. Five along-axis shotpoints and one 
off-axis fan shot will be recorded by 1200 Reftek ÔTexansÕ on loan from PASSCAL 
and FlexArray, with 100m receiver spacing in the central portion of the line 
and 300m on the outer ends. In addition, we hope to collect shallow CMP 
reflection data across active faults, and to deploy a small number of 
3-component seismographs to record anisotropy of the mid-to-lower crust. We 
expect this experiment to constrain Moho depth, velocity structure, and 
reflective character of the crust in this poorly known region, and tie together 
the 1986 PASSCAL survey in northwestern Nevada with the 1981 USGS survey across 
northeastern California.