Deep Borehole Measurements for Characterizing the Magma/Hydrothermal System at Long Valley Caldera, CA

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The Magma Energy Program of the Geothermal Technology Division is scheduled to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California in 1989. The drilling site is near the center of the caldera which is associated with numerous shallow (5-7 km) geophysical anomalies. This deep well will present an unparalleled opportunity to test and validate geophysical techniques for locating magma as well as a test of the theory that magma is still present at drillable depths within the central portion of the caldera. If, indeed, drilling indicates magma, the geothermal community will then be afforded the ... continued below

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137-141

Creation Information

Carrrigan, Charles R. March 21, 1989.

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Description

The Magma Energy Program of the Geothermal Technology Division is scheduled to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California in 1989. The drilling site is near the center of the caldera which is associated with numerous shallow (5-7 km) geophysical anomalies. This deep well will present an unparalleled opportunity to test and validate geophysical techniques for locating magma as well as a test of the theory that magma is still present at drillable depths within the central portion of the caldera. If, indeed, drilling indicates magma, the geothermal community will then be afforded the unique possibility of examining the coupling between magmatic and hydrothermal regimes in a major volcanic system. Goals of planned seismic experiments that involve the well include the investigation of local crustal structure down to depths of 10 km as well as the determination of mechanisms for local seismicity and deformation. Borehole electrical and electromagnetic surveys will increase the volume and depth of rock investigated by the well through consideration of the conductive structure of the hydrothermal and underlying regimes. Currently active processes involving magma injection will be studied through observation of changes in pore pressure and strain. Measurements of in situ stress from recovered cores and hydraulic fracture tests will be used in conjunction with uplift data to determine those models for magmatic injection and inflation that are most applicable. Finally, studies of the thermal regime will be directed toward elucidating the coupling between the magmatic source region and the more shallow hydrothermal system in the caldera fill. To achieve this will require careful logging of borehole fluid temperature and chemistry. In addition, studies of rock/fluid interactions through core and fluid samples will allow physical characterization of the transition zone between hydrothermal and magmatic regimes.

Physical Description

137-141

Source

  • DOE Research and Development for the Geothermal Marketplace, Proceedings of the Geothermal Program Review VII; San Francisco, CA, March 21-23, 1989

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  • Report No.: CONF-890352--22
  • Grant Number: None
  • Office of Scientific & Technical Information Report Number: 890518
  • Archival Resource Key: ark:/67531/metadc873943

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • March 21, 1989

Added to The UNT Digital Library

  • Sept. 21, 2016, 2:29 a.m.

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  • Dec. 5, 2016, 1:29 p.m.

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Carrrigan, Charles R. Deep Borehole Measurements for Characterizing the Magma/Hydrothermal System at Long Valley Caldera, CA, article, March 21, 1989; United States. (digital.library.unt.edu/ark:/67531/metadc873943/: accessed October 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.