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Title: Science guide for the Long Valley Caldera deep hole

Abstract

The Magma Energy Program of the US Department of Energy, Geothermal Technology Division, is planning to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California, in September 1988. The location of the well is in the central part of the caldera, coincident with a large number of shallow (5-7 km) geophysical anomalies identified through many independent investigations. Results from the hole will permit the following: direct investigation of the geophysical anomalies interpreted to be magma; investigation of the patterns and conditions of deep fluid circulation and heat transport below the caldera floor; determination of the amount of collapse and subsequent resurgence of the central portion of Long Valley caldera; and determination of the intrusion history of the central plutonic complex beneath the caldera, and establishment of the relationship of intrusive to eruptive events. The hole will thus provide a stringent test of the hypothesis that magma is still present within the central plutonic complex. If the interpretation of geophysical anomalies is confirmed, the hole will provide the first observations of the environment near a large silicic magma chamber. 80 refs., 7 figs., 2 tabs.

Authors:
;  [1]
  1. (eds.)
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (USA)
OSTI Identifier:
6069691
Report Number(s):
SAND-89-0155
ON: DE89013332
DOE Contract Number:
AC04-76DP00789
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 15 GEOTHERMAL ENERGY; CALDERAS; GEOTHERMAL EXPLORATION; CALIFORNIA; GEOLOGY; GEOPHYSICS; GEOTHERMAL ENERGY; GEOTHERMAL WELLS; HYDROTHERMAL SYSTEMS; MAGMA; VOLCANOES; ENERGY; ENERGY SOURCES; ENERGY SYSTEMS; EXPLORATION; FEDERAL REGION IX; GEOTHERMAL SYSTEMS; NORTH AMERICA; RENEWABLE ENERGY SOURCES; USA; WELLS; Geothermal Legacy; 580200* - Geophysics- (-1989); 150300 - Geothermal Exploration & Exploration Technology

Citation Formats

Rundle, J.B., and Eichelberger, J.C.. Science guide for the Long Valley Caldera deep hole. United States: N. p., 1989. Web. doi:10.2172/6069691.
Rundle, J.B., & Eichelberger, J.C.. Science guide for the Long Valley Caldera deep hole. United States. doi:10.2172/6069691.
Rundle, J.B., and Eichelberger, J.C.. Mon . "Science guide for the Long Valley Caldera deep hole". United States. doi:10.2172/6069691. https://www.osti.gov/servlets/purl/6069691.
@article{osti_6069691,
title = {Science guide for the Long Valley Caldera deep hole},
author = {Rundle, J.B. and Eichelberger, J.C.},
abstractNote = {The Magma Energy Program of the US Department of Energy, Geothermal Technology Division, is planning to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California, in September 1988. The location of the well is in the central part of the caldera, coincident with a large number of shallow (5-7 km) geophysical anomalies identified through many independent investigations. Results from the hole will permit the following: direct investigation of the geophysical anomalies interpreted to be magma; investigation of the patterns and conditions of deep fluid circulation and heat transport below the caldera floor; determination of the amount of collapse and subsequent resurgence of the central portion of Long Valley caldera; and determination of the intrusion history of the central plutonic complex beneath the caldera, and establishment of the relationship of intrusive to eruptive events. The hole will thus provide a stringent test of the hypothesis that magma is still present within the central plutonic complex. If the interpretation of geophysical anomalies is confirmed, the hole will provide the first observations of the environment near a large silicic magma chamber. 80 refs., 7 figs., 2 tabs.},
doi = {10.2172/6069691},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon May 01 00:00:00 EDT 1989},
month = {Mon May 01 00:00:00 EDT 1989}
}

Technical Report:

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  • In response to the need for closer, systematic monitoring of the Long Valley as a means of detecting changes that might precede volcanic activity in the area, a systematic program was begun to study hydrothermal activity and gas emissions. The initial effort to monitor hydrogen gas on one component of the gas phase that might be given off by an ascending body of magma is described. Hydrogen is a component of most magmatic gases, and there is now evidence for the release of hydrogen from magmas at shallow crustal depths prior to volcanic eruptions. Hydrogen may also be produced inmore » tectonically active areas by hydration reactions of rock-forming minerals with ground waters at depths where frictional stress results in moderately elevated temperatures. Because hydrogen is extremely mobile and relatively non-reactive once formed, it should ascend to the surface mobile and relatively non-reactive once formed, it should ascend to the surface easily through incipient fractures developed in tectonic fault zones. For these reasons, anomalous hydrogen emissions in the Long Valley area may be a good geochemical indication of tectonic or magmatic events.« less
  • The geologic and hydrologic setting of the hydrothermal system are described. The geochemical and thermal characteristics of the system are presented. A mathematical model of the Long Valley caldera is analyzed. (MHR)
  • This Field Procedures Manual is the comprehensive operations guide to be used to curate samples obtained from the INYO-4 site in the Long Valley Caldera, California. This site is a diamond drilling project in small-diameter holes that will produce continuous core. Fluid samples will also be of primary importance at this site. Detailed core and fluid handling procedures are therefore the major focus of this manual. The manual provides a comprehensive operations guide for the well-site geoscientists working at the Department of Energy/Office of Basic Energy Sciences (DOE/OBES) Continental Scientific Drilling Program (CSDP)/Thermal Regimes drill sites. These procedures modify andmore » improve those in previous DOE/OBES field manuals. 1 ref.; 6 figs.« less
  • The U.S. Geological Survey continued to monitor hydrologic and geochemical conditions in the Long Valley caldera during 1986. The monitoring is directed toward detecting changes in the hydrologic system caused by tectonic or magmatic processes. Data collected during 1986 include chemical and isotopic composition of water from selected stream sites, springs, and wells; pumpage from four geothermal wells; flow rates of selected springs and stream sites; mean daily water or gas temperatures at selected sites; mean daily atmospheric pressures and water levels at selected wells, and precipitation records for two sites. Seismicity within the caldera persisted at a relatively lowmore » level compared with the more active periods of 1978-84. The most significant events of seismicity that affected hydrologic monitoring sites in Long Valley during 1986 occurred during July, in response to the Chalfant Valley earthquakes, centered about 20 miles southeast of the caldera.« less
  • The Mammoth Lakes area in east-central California has experienced unusual seismicity and ground deformation since 1978, highlighted by four M > 6 earthquakes in May 1980 and by the discovery soon thereafter of a broad uplift within Long Valley caldera. Recurrent seismic swarms during June 1980-May 1982 raised concern over the possibility of renewed volcanic activity in the foreseeable future, prompting a USGS Notice of Potential Volcanic Hazard on 28 May 1982. As part of an intensified Long Valley monitoring effort sponsored by the USGS Volcanic Hazards program, a network of nine tilt sites was established near mammoth lakes inmore » May and July 1982. This report describes those stations and presents results from three tilt resurveys during July-August 1982. 8 references, 10 figures, 8 tables.« less