Document Type

Thesis

Abstract

The Rabbit Valley Salient is an enigmatic feature situated in the High Plateaus of Utah, a transition zone between the Basin & Range Province and the Colorado Plateau. It flanks the western edge of Thousand Lake Mountain and extends ~7 km into Rabbit Valley. Despite prior works and mapping of the region little is known about the structural nature and origin of the Rabbit Valley Salient. In the field a complex structural history is observed and four major bedrock units crop out in the following order from oldest to youngest; the North Horn Formation, Flagstaff Formation, an ashy sandstone unit referred to as the Tas unit in this study, JohnsonValley trachyandesite (Tjv), and Lake Creek Trachyte. The North Horn Formation and Flagstaff Formation are Cretaceous and early Eocene in age respectively, the Tas unit has been dated to ~36 Ma and the Tjv and Lake Creek trachyte have been dated to ~26 Ma and ~25 Ma respectively. Overlying all of these units are Quaternary aged boulder, alluvium, and colluvium deposits. The units underlying Tjv are deformed to varying degrees, the Tas and North Horn Formations exhibit isoclinal folds in some areas and the Flagstaff Formation is tilted in all observed outcrops. All units younger than the Quaternary age deposits are offset by normal faults with hanging walls down dropped to the west. Using data collected in the field during the summer of 2013 a geologic map of the Lyman 7.5’ Quadrangle was produced. Based on the map pattern and bedding data the underlying structure of the Rabbit Valley Salient was determined to be an anticline with a fold axis trending to the NNE. Two periods of deformation can be concluded from the data as well; a period that produced the folding and tilting prior to the deposition of Tjv and a period of extension associated with the formation of the Basin & Range province.

Date Awarded

2014

Department

Geology

Advisor 1

Christopher M. Bailey

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