The Steamboat Springs, Colorado Geothermal Systems: Geophysical and Geological Investigations

Abstract

A geophysical study of the Steamboat Springs Colorado area involving gravity, telluric profiling, audio-magnetotellurics (AMT), and self potential mapping combined with previous work in geology and geothermometry was made to assist in understanding of geothermal systems of the region. The two main zones of hot springs, one in Steamboat Springs and the other seven kilometers north at Routt Hot Springs, lie on or near normal and transverse faults associated with the upthrust of the Park Range. The audio-magnetotellurics show the geothermal activity to be non-shallow in origin. The telluric profiles denote a 500 to 750 meter wide zone with a one to two order magnitude drop in resistivity centered over Routt Hot Springs. The self potential mapping also defined a low (about -20 millivolts) in the same area. The geothermometry estimates for subsurface temperatures are between 125°C and 175°C for both spring systems. Since there are no recent volcanics in the region, it is assumed that the geothermal activity is the result of meteoric waters circulating along mountain front faults in an area above normal heat flow to depths of 4 to 5 kilometers.