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• 1. [Image] Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

  	The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and ...
  	Citation × Citation Citation Abstract Copy Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustic logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of Drilling were most Useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustic logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of Drilling were most Useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Close

• 2. [Image] Modeling Heat and Mass Transfer at the Mesa Geothermal Anomaly, Imperial Valley, California. Final Project Report

  	The geothermal reservoir modeling effort at the University of Colorado is reviewed briefly. Technical accomplishments during the final funding period 1 April 1978 to 30 November 1978 are described. It ...
  	Citation × Citation Citation Abstract Copy Title: Modeling Heat and Mass Transfer at the Mesa Geothermal Anomaly, Imperial Valley, California. Final Project Report Author: Kassoy, D.R. Year: 1979 The geothermal reservoir modeling effort at the University of Colorado is reviewed briefly. Technical accomplishments during the final funding period 1 April 1978 to 30 November 1978 are described. It is concluded that a physically viable mathematical model of an unexploited geothermal system can be constructed in terms of the fault zone controlled charging of the thermally active section of a reservoir Title: Modeling Heat and Mass Transfer at the Mesa Geothermal Anomaly, Imperial Valley, California. Final Project Report Author: Kassoy, D.R. Year: 1979 The geothermal reservoir modeling effort at the University of Colorado is reviewed briefly. Technical accomplishments during the final funding period 1 April 1978 to 30 November 1978 are described. It is concluded that a physically viable mathematical model of an unexploited geothermal system can be constructed in terms of the fault zone controlled charging of the thermally active section of a reservoir Close

• 3. [Image] Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1

  	The Roosevelt KGRA (Known Geothermal Resource Area) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the ...
  	Citation × Citation Citation Abstract Copy Title: Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1 Author: Nash, W.P. Year: 1976 The Roosevelt KGRA (Known Geothermal Resource Area) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the Mineral Mountains, a large tertiary granite batholith. The volcanics are high-silica rhyolites and occur as domes, flows and tuffs. Initial eruptions resulted in two flows of low viscosity, phenocryst-poor rhyolite. Later activity consisted of pyroclastic eruptions and the emplacement of at least 9 viscous domes. In addition to abundant glass the rhyolites contain alkali feldspar, plagioclase, biotite, iron-titanium oxides and small amounts of hornblende, allanite, apatite, zircon, sphene and topaz. Magmatic temperatures were about 700C and water fugacities ranged from 350 to 3450 bars. Based on water fugacity calculations it is concluded that there may have been one or more shallow magma chambers in the Mineral Range at depths of about 1.6 km. Title: Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1 Author: Nash, W.P. Year: 1976 The Roosevelt KGRA (Known Geothermal Resource Area) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the Mineral Mountains, a large tertiary granite batholith. The volcanics are high-silica rhyolites and occur as domes, flows and tuffs. Initial eruptions resulted in two flows of low viscosity, phenocryst-poor rhyolite. Later activity consisted of pyroclastic eruptions and the emplacement of at least 9 viscous domes. In addition to abundant glass the rhyolites contain alkali feldspar, plagioclase, biotite, iron-titanium oxides and small amounts of hornblende, allanite, apatite, zircon, sphene and topaz. Magmatic temperatures were about 700C and water fugacities ranged from 350 to 3450 bars. Based on water fugacity calculations it is concluded that there may have been one or more shallow magma chambers in the Mineral Range at depths of about 1.6 km. Close

• 4. [Image] Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems

  	A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in ...
  	Citation × Citation Citation Abstract Copy Title: Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems Author: Capuano, R.M. Year: 1978 A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in a hot-water geothermal system. Samples of -80 mesh soil were collected at 30.5 m intervals along traverses crossing known structures, surficial geothermal alteration, and exploration well sites, and were analyzed using a Gold Film Mercury Detector. Strong mercury anomalies occur at locations along known structures in close proximity to subsurface thermal activity; examples include areas over hot spring deposits and near a shallow producing well. In contrast, background mercury concentrations are present in nearby locations with little or no indication of subsurface thermal activity, such as areas around deep marginal producing wells and dry wells, and areas lacking hot spring deposits. These results indicate that mercury geochemical surveys can be useful for identifying and mapping structures controlling fluid flow in geothermal systems and for delineating areas overlying near-surface thermal activity. Soil mercury geochemistry thus provides information which may aid in the cost-effective selection of exploratory well sites Title: Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems Author: Capuano, R.M. Year: 1978 A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in a hot-water geothermal system. Samples of -80 mesh soil were collected at 30.5 m intervals along traverses crossing known structures, surficial geothermal alteration, and exploration well sites, and were analyzed using a Gold Film Mercury Detector. Strong mercury anomalies occur at locations along known structures in close proximity to subsurface thermal activity; examples include areas over hot spring deposits and near a shallow producing well. In contrast, background mercury concentrations are present in nearby locations with little or no indication of subsurface thermal activity, such as areas around deep marginal producing wells and dry wells, and areas lacking hot spring deposits. These results indicate that mercury geochemical surveys can be useful for identifying and mapping structures controlling fluid flow in geothermal systems and for delineating areas overlying near-surface thermal activity. Soil mercury geochemistry thus provides information which may aid in the cost-effective selection of exploratory well sites Close