Publication Date:
2012-08-01
Description:
The Wassuk Range fault zone is an 80-km-long, east-dipping, high-angle normal fault that flanks the eastern margin of the Wassuk Range in central Nevada. Observations from two alluvial fan systems truncated by the fault yield information on the vertical slip rate and Holocene earthquake history along the range front. At the apex of the Rose Creek alluvial fan, radiocarbon dating of offset stratigraphy exposed in two fault trenches shows that multiple earthquakes resulted in 7.0 m of vertical offset along the fault since approximately 9400 cal B.P. These data yield a Holocene vertical slip rate of 0.7+ or -0.1 mm/yr. The south trench exposure records at least two faulting events since approximately 9400 cal B.P., with the most recent displacement postdating approximately 2810 cal B.P. The north trench exposure records an approximately 1 m offset between approximately 610 cal B.P. and A.D. approximately 1850, a 1.3-m minimum offset prior to approximately 1460 cal B.P., and one earlier undated earthquake of a similar size. Variations in stratigraphy and limited datable material preclude a unique correlation of paleoevents between the two trenches. Approximately 25 km north, the range-front fault has truncated and uplifted a remnant of the Penrod Canyon fan by 〉40 m since the surface was deposited approximately 113 ka, based on cosmogenic dating of two large boulders. These data allow an estimate of the minimum late Pleistocene vertical slip rate at 〉0.3-0.4 mm/yr for the Wassuk Range fault zone. Online Material: Tables summarizing radiocarbon and cosmogenic analyses, photos of rocks sampled for cosmogenic analyses, and figures summarizing cosmogenic exposure age estimates.
Print ISSN:
0037-1106
Electronic ISSN:
1943-3573
Topics:
Geosciences
,
Physics
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