Abstract Title: Mesozoic and Cenozoic Structural Evolution of the Great Basin 
near 115¡30ÕW Longitude

Abstract Author(s): Taylor, Wanda J. Taylor Dept. of Geoscience, University of 
Nevada Las Vegas  

Abstract: The region around 115¡30ÕW longitude lies in the core of the Great 
Basin and contains well-documented structures from multiple deformational 
events including contraction, supraslab extension, and extension associated 
with the development of the strike-slip plate boundary in California and 
western Nevada. These deformations undoubtedly influenced the entire crust. 
Thus, understanding upper crustal tectonism and structures aids in interpreting 
shallow to lower crustal geophysical data. The ~Cretaceous Sevier belt (SB) 
extends from SE California into Canada. A hinterland thrust belt near 115¡30ÕW 
is now suggested to be part of the SB. This belt, the Central Nevada thrust 
belt, generally comprises ~3 stacked thrust sheets, as in the Timpahute and Mt. 
Irish ranges, and the Pancake and White Pine ranges. Characteristically, the 
major thrusts are E-vergent with long, steep ramps that cut at least as deep as 
Cambrian rocks. The major thrusts can be traced 10Õs of km along strike, 
despite Cenozoic extensional overprinting. Major extension occurred from late 
Eocene to late Miocene along 115¡30ÕW. Tertiary extensional belts locally 
overprint each other resulting in areas with only one significant extension 
(e.g., southern Worthington Mountains) and others with 3 - 4 (e.g., North 
Pahroc Range). Tertiary transverse faults segment the area. Some are 
strike-slip faults, such as in Horse Range. Others, as in the Hiko and 
Timpahute ranges, accommodate N-S extension suggesting changes in local stress 
regimes through time Pliocene(?) - Quaternary normal faults typically have 
multiple-event scarps. Examples include the Hiko fault, California Wash fault, 
and faults near Las Vegas. The horizontal spacing between these faults is 
greater than that of the Tertiary faults, which may reflect changes in 
extensional rates, style or thermal regime of the crust.