LATE PLEISTOCENE SLIP RATES ALONG THE PANAMINT VALLEY FAULT ZONE, EASTERN CALIFORNIA

Open Access
Author:
Hoffman, William Robert
Graduate Program:
Geosciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 13, 2009
Committee Members:
  • Dr Eric Kirby, Thesis Advisor
Keywords:
  • Panamint Valley
  • slip rate
  • faults
  • eastern california
  • cosmogenic radionuclides
  • LiDAR
Abstract:
The Panamint Valley fault zone (PVFZ) is one of the primary structures accommodating right lateral shear across the Eastern California Shear Zone. Current slip-rate estimates are either long-term estimates based on total offset of the system and bounds on the initiation of fault slip, or estimates that rely on undated alluvial deposits. Using field surveys and high-resolution airborne LiDAR digital topography, I utilize displaced alluvial deposits at two localities, Happy Canyon and Manly Peak Canyon, to provide new slip-rate estimates along the PVFZ. Chronologic control is provided by a newly developed chronosequence of soils in Panamint Valley, radiocarbon dating of lacustrine tufa associated with shoreline deposits, and terrestrial cosmogenic nuclide (10Be) dating of alluvial fan surfaces. At Manly Peak Canyon, debris flow levees offset 26.5 ± 3.8 m with a maximum surface age of 12.5 ± 1.4 ka yield a minimum extension rate of 2.1 ± 0.5 mm/yr. At Happy Canyon, displaced alluvial markers demonstrate that slip along northeast-striking fault strands in the right-stepping portion of the fault zone is purely dip-slip with no lateral component. Here, an alluvial fan complex cut by a series of normal faults with total extension of 56.0 ± 10.3 m has surface age estimates from a calibrated soil chronofunction ranging from ~16 - 40 ka, yielding a minimum extension rate of 2.7 ± 1.5 mm/yr. Additionally, a 20.7 ± 5.2 ka surface at Happy Canyon is cut by a fault scarp with 68.1 ± 2.0 m of vertical offset, which yields a preliminary Late Pleistocene minimum throw rate of 3.3 ± 0.7 mm/yr. Results from this thesis provide the only two slip-rate estimates along the PVFZ with chronologic control, and reveal along-strike variations in horizontal displacement direction that appear coordinated with increased subsidence in the northern part of the valley.