Structural Analysis of the Arapahoe Butte Quadrangle - Freemont and Hot Springs Counties, Wyoming
Faculty Mentor
Chad Pritchard
Presentation Type
Poster
Start Date
4-14-2026 2:00 PM
End Date
4-14-2026 4:00 PM
Location
PUB NCR
Primary Discipline of Presentation
Geosciences
Abstract
This study presents a structural interpretation of the Arapahoe Butte Quadrangle, located in Fremont and Hot Springs Counties of central Wyoming. The analysis focuses on the northwest‑trending anticline on Lysite Mountain, a feature attributed to Laramide orogenic deformation. By comparing mapped structures with regional tectonic patterns, this work examines how local folding and faulting relate to the broader geologic history of the area. The anticline exposes a stratigraphic sequence ranging from Cambrian to Permian limestones through Permian to Jurassic siltstones and sandstones, overlain by Quaternary volcaniclastic deposits and gravel. Multiple unconformities separate these depositional intervals, reflecting episodic tectonic and environmental change (Thaden, 1980). Structural measurements indicate that the Lysite Mountain Anticline possesses an axial plane striking 325.7° with a dip of 60.4°E, and a hinge line trending 326.3° and plunging 01.1°E, characterizing it as a gently plunging fold. The geometry of the fold, combined with regional deformation trends, supports its formation during the Laramide Orogeny, active between approximately 80 and 55 million years ago (Hildegard et al, 2003).
Recommended Citation
Slanga, Emersen, "Structural Analysis of the Arapahoe Butte Quadrangle - Freemont and Hot Springs Counties, Wyoming" (2026). 2026 Symposium. 4.
https://dc.ewu.edu/srcw_2026/ps_2026/p3_2026/4
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Structural Analysis of the Arapahoe Butte Quadrangle - Freemont and Hot Springs Counties, Wyoming
PUB NCR
This study presents a structural interpretation of the Arapahoe Butte Quadrangle, located in Fremont and Hot Springs Counties of central Wyoming. The analysis focuses on the northwest‑trending anticline on Lysite Mountain, a feature attributed to Laramide orogenic deformation. By comparing mapped structures with regional tectonic patterns, this work examines how local folding and faulting relate to the broader geologic history of the area. The anticline exposes a stratigraphic sequence ranging from Cambrian to Permian limestones through Permian to Jurassic siltstones and sandstones, overlain by Quaternary volcaniclastic deposits and gravel. Multiple unconformities separate these depositional intervals, reflecting episodic tectonic and environmental change (Thaden, 1980). Structural measurements indicate that the Lysite Mountain Anticline possesses an axial plane striking 325.7° with a dip of 60.4°E, and a hinge line trending 326.3° and plunging 01.1°E, characterizing it as a gently plunging fold. The geometry of the fold, combined with regional deformation trends, supports its formation during the Laramide Orogeny, active between approximately 80 and 55 million years ago (Hildegard et al, 2003).
