Transient model of the geothermal system of the Long Valley Caldera, California

Journal Article · Tue Nov 10 04:00:00 EDT 1942 · J. Geophys. Res.; (United States)

OSTI ID:6480218

Blackwell, D D

The present-day geothermal system underlying the southern one third of the Long Valley Caldera is discussed, based on interpretation of the complex shapes of temperature-depth curves and the correlation of this interpretation with hydrologic and geologic data. The temperature-depth curves are interpreted using a simple analytical model for transient flow of hot water in a confined aquifer. The results give information on the transient nature of the geothermal system operating in the Long Valley caldera and on the application of the analytical model to a complex geothermal system. At the present time there is major west-east flow of hot fluid in two aquifers. The first aquifer occurs at a depth of 12--120 m. The aquifer is charged with water at a temperature greater than 175/sup 0/C west of Case Diablo Hot Springs which then flows eastward at a velocity of the order of 100--200 m/yr to exit in the hot springs along Hot Creek and at the edge of Lake Crowley. Temperatures systematically decrease eastward in the shallow aquifer. In order to interpret the temperature data in Long Valley caldera a model of the thermal effects of flow in a shallow aquifer is discussed, and the results are found to be consistent with geologic and hydrologic information. The shapes of inversions of temperature versus depth curves indicate that the age of this aquifer rangers between 50 and 700 years; the best estimate is 500--700 years. The initiation of hot water flow in the shallow aquifer coincides with extrusive activity associated with the Mono/Inyo craters chain of rhyolitic centers, which was active over a linear distance of about 40 km during the period 500--600 years ago. A second aquifer occurs just below the top of the Bishop Tuff at a depth of approximately 700 m in hole Mammoth 1.

• Research Organization: Department of Geological Sciences, Southern Methodist University, Dallas, Texas
• OSTI ID: 6480218
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 90:B13; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150201* -- Geology & Hydrology of Geothermal Systems-- USA-- (-1989)
AQUIFERS
CALDERAS
CALIFORNIA
FEDERAL REGION IX
FLUID FLOW
GEOLOGY
GEOTHERMAL SYSTEMS
GROUND WATER
HYDROGEN COMPOUNDS
HYDROLOGY
LONG VALLEY
NORTH AMERICA
OXYGEN COMPOUNDS
TEMPERATURE DISTRIBUTION
TRANSIENTS
USA
WATER