Bibliographic source: Geoindex lat-long search 



Author: Sonderegger, J.L., J.D. Schofield, R.D. Berg and M.L, 

 Mannick 



Title: The Upper Centennial Valley, Beaverhead and Madison 

 Counties, Montana 



Series: MBMG Memoir 50 



Date: 1982 



This study was instigated as an evaluation of the geotherraal 

 potential of the Centennial Valley and adjacent areas of the Upper 

 Madison valley. The structural geology of the Centennial Valley 

 is described in detail, and the stratigraphy and paleogeography of 

 Cenozoic volcanic and volcaniclastic rocks also receives emphasis. 

 Outcrops on the southern end of the Gravelly Range are dominant ly 

 the Huckleberry Ridge Tuff and other Quaternary volcanics mantling 

 Paleozoic rocks. Outcrops are separated from the Lake by several 

 miles of dune sand and Quaternary alluvium. Outcrops to the south 

 across the Centennial fault are not mapped here but are described 

 as including formations ranging in age from lower Cretaceous to 

 Precambrian. 



Ground-water chemistry from surficial aguifers on the north side 

 of the valley (alluvium and aeolian sand) supports some mixing of 

 deep-circulating geothermal water. Thermal imaging of the northern 

 margin of Upper Red Rock Lake also supports some leakage of warm 

 Madison Group ground water into the lake and nearby aguifers. 

 Structural interpretation shows an inferred fault trace passing 

 between Upper Red Rock and Swan Lakes, which is interpreted as the 

 flow path for deeply circulating ground water discharge. 



Geothermometry is interpreted as indicating only moderate reservoir 

 temperatures of 45 degrees C or so (chalcedony thermometer). 



Appendices include well summary and numerous water guality analyses 

 which should be copied. 



Bibliographic source: Geoindex lat-long search 



Author: Witkind, I.J. 



Title: Geologic map of the Centennial Mountains Wilderness Study 

 area and contiguous areas, Idaho and Montana. 



