Date of Award
M.S. in Engineering Science
Jennifer N. Gifford
University of Mississippi
The goal of this project was to produce geologic maps of the Skull Ridge, and Dayton South, Wyoming 7.5-Minute Quadrangle (Scale 1:24,000), from the northern Bighorn Mountains, Wyoming Cratonic Province (WCP). Detailed analysis of the geology within these quadrangles was performed using geochemistry, geochronology, thin section petrography, and structures of geologic units. The Bighorns are divided into northern and southern sections where the north is characterized by an Archean felsic batholith with cross-cutting plutonic dikes, and the south is composed of an Archean gneiss complex. The basement rocks in this area were formed ~2900-2500 Ma during a series of geologic events that included regional metamorphism, plutonism, and a deformational period. The margins of the Bighorn Mountains are characterized by an abundance of sedimentary rocks that overlie the crystalline basement. Geologic units in the Bighorns range from Precambrian to Tertiary in age. Radiometric age dating results have been used to verify the accuracy of ages published in previous geochronological studies in the Bighorns. Geochemical analysis has further supported the hypothesis that crystalline rocks in this area are sourced from a subduction zone tectonic setting that led to the creation of an evolved TTG suite. Structural analysis has concluded that structural elements observed in the northern Bighorn Mountains resulted from basement cored uplifts which correlate with other published findings. This geologic map will provide the research community with accurate geochemical, geochronological, and structural data from the Skull Ridge and Dayton South Quadrangles that may be used to develop a more comprehensive understanding of the regional geology of the Bighorn Mountains and WCP.
Andreoli, Robert Charles, "Geochronological, Geochemical, Petrographical, and Structural Analysis of the Northeast Bighorn Mountains, Sheridan County, Wyoming, USA" (2023). Electronic Theses and Dissertations. 2477.
Available for download on Saturday, September 13, 2025