Active faulting and quaternary paleohydrology of the Truckee fault zone north of Truckee, California

Aaron Melody

Graduation Date

2009

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Environmental Systems: Geology, 2009

Committee Chair Name

Mark Hemphill-Haley

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Holocene faulting, Northwest Walker Lane tectonics, Sierra Nevada tectonics, Quaternary hydrology, Sierra Nevada Holocene climate, Humboldt State University -- Theses -- Geology

Abstract

Active faulting has been documented along the northwest-striking Mohawk Valley fault zone (2-3 normal-dextral rupture events in the Holocene with geologic slip rates of ~0.2mm/yr) and in the Lake Tahoe basin (mostly on north-striking normal faults with geologic slip rates of up to 0.4 mm/yr). Evidence for Holocene faulting in the region between these zones; for example along the Truckee fault zone, has been sparse to absent. Soil cores and trenches were hand-dug in a meadow north of Truckee, California bound by a low (~1m) north-south trending, east-facing scarp. Radiocarbon age estimates of organic sediment indicate the meadow was a marsh during the Late Quaternary and was abruptly infilled and/or desiccated with the deposition of the ~7,000 yr B.P Tsoyowata tephra (Mt. Mazama). Both the tephra and the marsh sediment are offset ~50-100 cm across a vertical fault striking sub-parallel with the scarp. This study provides evidence for at least one surface-faulting event during the Holocene and possibly another in the late Pleistocene along the Truckee fault zone. These findings may aid in the identification of other seismic sources capable of significant ground rupture in the area.

https://scholarworks.calstate.edu/concern/theses/6m311r891

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