Date Thesis Awarded

4-2014

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Geology

Advisor

Christopher M. Bailey

Committee Member

Brent E. Owens

Committee Member

Frederick H. Smith

Abstract

The High Plateaus of central Utah form a transition zone between the physiographic provinces of the Basin & Range and Colorado Plateau. The High Plateaus are characterized by a system of steeply-dipping normal faults and associated seismicity. My research focuses on understanding the movement and history of the Thousand Lake Fault (TLF) system, which is the easternmost major fault of the High Plateaus province bounding the Colorado Plateau. The main strand of the TLF dips westward and strikes N-S and NW-SW. Kinematic evidence suggests down-to-the-west normal slip on the TLF and total offset of 800-1000 m, with displacement decreasing to the northeast as displacement is transferred west to the Paradise Fault system. The TLF displaces volcanic rocks of Tertiary age from the top of Thousand Lake Mountain to an elevation up to 500 m lower on the hanging wall. The TLF offsets Quaternary boulder deposits near the Yellow Ledges, providing a minimum age constraint for most recent fault activity in the Quaternary.

Brittle deformation features in the fault zone suggest a seismogenic history for the fault. However, relative smoothness of the longitudinal profiles of channels crossing the fault reveal that mass movement controls slope topography and the most recent fault rupture is obscured by surficial deposits. Stratigraphic relations and a previously dated boulder fan exposure age demonstrate that recent movement on the TLF occurred in the last 200 ky. The large displacement on the fault (as great as 1,000 m) indicates that the fault was extremely active for a protracted period fault and is therefore an older structure along the boundary of the Transition Zone. Based on active extension patterns of the Great Basin, the fault may have initiated in the Late Miocene in response to Mid-Cenozoic stresses.

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