Thermal Gradient Holes At Long Valley Caldera Geothermal Area (Lachenbruch, Et Al., 1976)

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Exploration Activity: Thermal Gradient Holes At Long Valley Caldera Geothermal Area (Lachenbruch, Et Al., 1976)

Exploration Activity Details
Location Long Valley Caldera Geothermal Area
Exploration Technique Thermal Gradient Holes
Activity Date 1962 - 1973

Usefulness not indicated
DOE-funding Unknown

 
Notes
Between 1962 and 1973, 11 temperature-gradient test holes were drilled outside the caldera rim to depths of 113 to 271 m. These drill holes, in addition to some 36 temperature profiles from holes completed to depths ranging from 5 to 325 m within the caldera, were drilled for the purposes of data collection for a number of U.S. Geological Survey heat flow studies.[1][2] These studies showed that minimal thermal gradients of <55°C/km occur along the caldera rim, which were interpreted as areas of recharge into the caldera groundwater system. Thermal gradients near hot spring occurrences were significantly higher (up to 910°C/km), but decrease with depth and typically reversed within the first hundred meters of the boreholes.

 
References


Additional References
  1. Arthur H. Lachenbruch,Michael L. Sorey,Robert Edward Lewis,John H. Sass. 1976. The Near-Surface Hydrothermal Regime of Long Valley Caldera. Journal of Geophysical Research. 81(5):763-768.
  2. J.L. Smith,R.W. Rex. 1977. Drilling results from eastern Long Valley Caldera. (!) : American Nuclear Society. Report No.: Energy and Mineral Resource Recovery.