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

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

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

Usefulness useful
DOE-funding Unknown

Eleven temperature-gradient test holes were drilled to depths of 113 to 271 m outside the caldera rim between 1962 and 1973 as a part of several U.S. Geological Survey heat flow studies of the Long Valley area. These drill holes, in addition to some 36 temperature profiles from holes completed to depths ranging from 5 to 325 m within the caldera, included the DC well and the CH1-7 core holes in the eastern part of the caldera, among others.[1][2] The maximum encountered temperature reported for these holes was approximately 110°C in CH7. Temperature reversals were detected in wells CH3, CH5, and CH7, and suggest that warm water flows laterally through the groundwater system to the east from Hot Creek Gorge toward Lake Crowley. 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.


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.