Document Type
Thesis
Abstract
The Fish Lake Plateau in south central Utah lies within a transitional boundary, separating the Colorado Plateau Province to the east from the Basin & Range Province to the west, and is characterized by basins and plateaus at high elevations above 2500 m. The Fish Lake basin, located within this Transition Zone, contains the largest natural alpine lake in the state of Utah called Fish Lake. Approximately 2 by 7 km long, Fish Lake is situated within a NE-SW striking structural graben ~500-900 ka and contains glacial sediment from at least the last two periods of glacial events within the American southwest. Sediment within the basin conceals the true amount of displacement along the master fault, beneath the Mytoge Crest ridgeline on the SE side of the graben. A previous gravity survey estimated sediment thickness to be ~100 m along one transect across the width of the lake. To understand more about the underlying bedrock and sediment geometry, a comprehensive gravity survey over Fish Lake and the surrounding hillsides was used to determine gravitational acceleration anomalies within the Fish Lake basin and corresponding sediment thicknesses. Gravity anomalies, otherwise known as Bouguer Anomalies display a similar NE-SW striking trend, paralleling the overall orientation of the Fish Lake graben and indicate a similar trend in sediment infill structure. Four cross sections over the lake show sediment thickness to vary from 90 to 230 m, increasing towards the NE section near a submerged glacial moraine of Bull Creek age. Significant drops in anomaly values over the surface of the lake reveal a buried NE-SW striking half-graben structure that terminates towards the NE around the submerged moraine and leads into the main graben of Fish Lake, down-stepping towards the SE side. Maximum offset along the master fault of Mytoge Crest is conservatively estimated to be ~620 m. Fish Lake remains a uniquely viable area for coring thick sediment deposits in order to understand more about the glacial history of the American southwest, paleoenvironment, and tectonic history of the region.
Date Awarded
2014
Department
Geology
Advisor 1
Christopher M. Bailey
Recommended Citation
Wenrich, Erika, "Structural geometry and sediment thickness in the Fish Lake" (2014). Geology Senior Theses. William & Mary. Paper 330.
https://scholarworks.wm.edu/geologyseniors/330
