Document Type
Thesis
Abstract
The Fish Lake Plateau is located in the High Plateaus of central Utah, a transitional zone between the Colorado Plateau and Basin & Range geologic provinces. The Basin & Range experienced major Cenozoic extension totaling 100-300%. The Colorado Plateau experienced major Cenozoic uplift of ~2 km. The High Plateaus exhibit characteristics of both adjoining provinces, but much remains to be understood about the structural history and geometry of the region. The Fish Lake Plateau, characterized by topographic lineaments that commonly demarcate graben-bounding normal faults, provides an excellent study area for examining the predominant structural features of the High Plateaus. This project sought to elucidate the structural geology of the northern Fish Lake Plateau through geologic mapping and construction and restoration of geologic cross sections. To this end, we aim to describe the fault geometry, quantify total extension and displacement to understand the fault kinematics, discern the temporal history of deformation, and place deformation in the Fish Lake Plateau into a larger regional context The study area is largely encompassed by the Mt. Terrill and Hilard Mountain 7.5’ quadrangles, and lies astride the divide between the Colorado and Great Basin drainage systems. The region is underlain by Cretaceous to lower Tertiary sedimentary units, which are uncomformably overlain by Tertiary volcanic rocks. These are together mantled with an array of surficial deposits. Normal faults on the Fish Lake Plateau generally cut both the volcanic and sedimentary stratigraphies, but not the younger surficial deposits. The structural geometry of the northern Fish Lake Plateau is dominated by steeply-dipping normal faults that bound a suite of NNW to NE-trending grabens and half grabens. Grabens range from 5 to 12 km in length, and | to 2 km in width, with maximum displacements of less than 700 m. Total extension across these faults is less than 10%. The oldest grabens form broad valleys with abundant colluvium; based on age relations from the southern Fish Lake Plateau, the oldest grabens in the Mt. Terrill and Hilgard Mountain quadrangles range may be as old as 5 Ma. Petes Hole is a distinctive, down-to-the west, half graben complex with an internal drainage consistent with Quaternary faulting that has yet to be integrated into the Lost Creek drainage. As the predominate sets of faults are oriented nearly perpendicularly to one another and occur within a relatively close temporal span, a uniaxial stress field model (6;>02=03) 1s proposed to explain the changing orientation. This would suggest deformation of Fish Lake Plateau distinct from far-field stresses impacting the adjoining geologic provinces.
Date Awarded
2009
Department
Geology
Advisor 1
Christopher M. Bailey
Recommended Citation
Buckely, Trevor R., "Structural History and Geometry of the Northern Fish Lake Plateau, Central Utah" (2009). Geology Senior Theses. William & Mary. Paper 205.
https://scholarworks.wm.edu/geologyseniors/205
