The purpose of the CGS Open-File Report OF-17-04, Geologic Map of the Hartsel Quadrangle, Park County, Colorado is to describe the geology, mineral and groundwater resource potential, and geologic hazards of this 7.5-minute quadrangle located in the beautiful South Park basin in the central Rocky Mountains of Colorado. The geologic map plates were created using field maps and notes, structural measurements, and photographs generated by the investigators. Includes 2 plates and GIS data in a single zip file. Digital ZIP download. OF-17-04D
This mapping project was funded jointly by the U.S. Geological Survey through the STATEMAP component of the National Cooperative Geologic Mapping Program, which is authorized by the National Geologic Mapping Act of 1997, and also by the CGS using the Colorado Department of Natural Resources Severance Tax Operational Funds. The CGS matching funds come from the severance paid on the production of natural gas, oil, coal, and metals. Geologic maps produced through the STATEMAP program are intended as multi-purpose maps useful for land-use planning, geotechnical engineering, geologic-hazard assessment, mineral-resource development, and ground-water exploration.
From the Geologic Setting (Plate 2):
The Hartsel quadrangle sits nearly in the center of the complex South Park Laramide structural basin. Generally, the basin can be described as an asymmetrical down-faulted feature, dipping to the east. It is bounded by two northwest-trending uplifts: the Sawatch uplift to the west and the Front Range uplift to the east. The west-verging Elkhorn thrust, which places Proterozoic intrusive and metamorphic rocks within the Front Range uplift over Phanerozoic sediments in the basin, passes just east of the quadrangle. Seismic data and deep oil and gas well logs indicate that a series of imbricate thrust faults extend west, and in front of, the Elk horn thrust fault. The Hartsel uplift is a westward-jutting structural salient of the Front Range uplift that brings Proterozoic rocks farther into the basin south of the town of Hartsel. The quadrangle also spans the late Paleozoic boundary between the central Colorado trough (DeVoto, 1972) to the west and Frontrangia (Mallory, 1958) to the east. The Neogene Rio Grande rift system lies to the west of South Park Basin in the upper Arkansas River valley. Examples of Neogene extension can be found throughout South Park, as described by Stark and others (1949), De Voto (1971), and Ruleman and others (2011). In addition, there is evidence of ongoing local deformation related to dissolution and possible collapse of Paleozoic evaporite deposits across much of the west side of the basin (Kirkham and others, 2012).