Heat flow in the Coso geothermal area, Inyo County, California
Obvious surface manifestations of an anomalous concentration of geothermal resources at the Coso geothermal area, Inyo County, California, include fumarolic activity and associated hydrothermally altered rocks. Pleistocene volcanic rocks associated with the geothermal activity include 38 rhyolite domes occupying a north trending structural and topographic ridge and numerous basaltic cinder cones and lava flows partly surrounding its southern half. In an investigation of the thermal regime of this Basin and Range geothermal area, temperature measurements were made in 25 shallow and 1 intermediate depth borehole. Geothermal gradients ranged from 25.3 /sup 0/C/km to 906. /sup 0/C/km. The high gradients arise from convecting hot water and former convective transport of heat by dikes that fed the domes and flows. Thermal conductivity measurements were made on 312 samples from cores and drill cuttings.. The actual process by which heat is transferred is rather complex; however, the heat flow determinations can be divided into two groups. The first group, less than 4.0 HFU, are indicative of regions with primarily conductive regimes, although deep-seated mass transfer is implied. The second group, greater than 4.0 HFU, are characteristics of regions with considerable convective heat transfer in the shallow subsurface. Heat transferred by convection of water would be rapidly exhausted if it were not intermittently supplied with heat energy from depth; therefore the heat flow data substantiate the concept that the surface hydrothermal activity and associated volcanic rocks are products of a long-lived magmatic system that has periodically erupted lava during the past 0.3--1.0 m.y. This magmatic system is the crustal heat source of the present-day Coso geothermal system (1 HFU=41.87 mW/m/sup 2/).
- Research Organization:
- GeoThermal Services, Inc., San Diego, California 92131
- OSTI ID:
- 5231784
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 85:B5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSO HOT SPRINGS
HEAT FLOW
CONVECTION
GEOTHERMAL GRADIENTS
MASS TRANSFER
THERMAL CONDUCTIVITY
THERMAL WATERS
CALIFORNIA
NORTH AMERICA
PHYSICAL PROPERTIES
TEMPERATURE GRADIENTS
THERMODYNAMIC PROPERTIES
USA
WESTERN REGION
150201* - Geology & Hydrology of Geothermal Systems- USA- (-1989)