Corwin Springs Known Geothermal Resources Area, Park County, Montana
The Corwin Springs Known Geothermal Resources Area (KGRA) is contiguous to Yellowstone National Park along a part of the northern boundary of the park near Gardiner, Park County, Mont. The area contains two known sites of hot-spring activity--LaDuke Spring, 2.8 km southeast of the small resort community of Corwin Springs, and Bear Creek Spring, 2.6 km east of Gardiner. LaDuke Spring issues from brecciated quartzite and has a flow rate of 380 1/min, a surface water temperature of 65°C, a silica-geothermometer temperature of 68.7°C, and a Na-K-Ca geothermometer temperature of 76.8°C. Bear Creek Spring issues from limestone and has a flow rate of 4 1/min, a surface water temperature of 32°C, a silica temperature of 46.7°C, and a Na-K-Ca temperature of 87.2°C. The springs, which are actively depositing travertine, are on or near the trace of the Gardiner fault-a high-angle reverse fault which forms the southwestern boundary of the Beartooth uplift. Features that make the Corwin Springs KGRA potentially significant include: (1) Proximity of the Corwin Springs area to significant Pliocene and Pleistocene volcanism in Yellowstone National Park and related geothermal activity, (2) existence of a large potential geothermal reservoir in the northern extension of the Sepulcher Mountain graben, (3) localization of thermal activity along the Gardiner fault in the Corwin Springs area, (4) occurrence of negative gravity anomaly centered over the northern end of the Sepulcher Mountain graben, (5) existence of negative magnetic anomaly in the Corwin Springs area, (6) location of the area within the Intermountain seismic belt, (7) evidence of recent tectonism in the area, as demonstrated by Pleistocene and Holocene faulting, and (8) observed surface temperatures and estimated geochemical temperatures of the two known hot springs (features which do not indicate high subsurface temperatures).