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• 1. [Image] Geology of the Beowawe geothermal system, Eureka and Lander Counties, Nevada

  	A geologic study is described undertaken to evaluate the nature of structural and stratigraphic controls within the Beowawe geothermal system, Eureka and Lander Counties, Nevada. This study includes geologic ...
  	Citation × Citation Citation Abstract Copy Title: Geology of the Beowawe geothermal system, Eureka and Lander Counties, Nevada Author: Struhsacker, E.M. Year: 1980 A geologic study is described undertaken to evaluate the nature of structural and stratigraphic controls within the Beowawe geothermal system, Eureka and Lander Counties, Nevada. This study includes geologic mapping at a scale of 1:24,000 and lithologic logs of deep Chevron wells. Two major normal fault systems control the configuration of the Beowawe geothermal system. Active hot springs and sinter deposits lie along the Malpais Fault zone at the base of the Malpais Rim. The Malpais Rim is one of several east-northeast-striking, fault-bounded cuestas in north central Nevada. A steeply inclined scarp slope faces northwest towards Whirlwind Valley. The general inclination of the volcanic rocks on the Malpais dip slope is 5/sup 0/ to 10/sup 0/ southeast; DOE/ID/12079-T1; ESL-37 Title: Geology of the Beowawe geothermal system, Eureka and Lander Counties, Nevada Author: Struhsacker, E.M. Year: 1980 A geologic study is described undertaken to evaluate the nature of structural and stratigraphic controls within the Beowawe geothermal system, Eureka and Lander Counties, Nevada. This study includes geologic mapping at a scale of 1:24,000 and lithologic logs of deep Chevron wells. Two major normal fault systems control the configuration of the Beowawe geothermal system. Active hot springs and sinter deposits lie along the Malpais Fault zone at the base of the Malpais Rim. The Malpais Rim is one of several east-northeast-striking, fault-bounded cuestas in north central Nevada. A steeply inclined scarp slope faces northwest towards Whirlwind Valley. The general inclination of the volcanic rocks on the Malpais dip slope is 5/sup 0/ to 10/sup 0/ southeast; DOE/ID/12079-T1; ESL-37 Close

• 2. [Image] Interpretation of a dipole-dipole electrical resistivity survey, Colado geothermal area, Pershing County, Nevada

  	An electrical resistivity survey in the Colado geothermal area, Pershing County, Nevada has defined areas of low resistivity on each of five lines surveyed. Some of these areas appear to be fault controlled. ...
  	Citation × Citation Citation Abstract Copy Title: Interpretation of a dipole-dipole electrical resistivity survey, Colado geothermal area, Pershing County, Nevada Author: Mackelprang, C.E. Year: 1980 An electrical resistivity survey in the Colado geothermal area, Pershing County, Nevada has defined areas of low resistivity on each of five lines surveyed. Some of these areas appear to be fault controlled. Thermal fluids encountered in several drill holes support the assumption that the hot fluids may be associated with areas of low resistivity. The evidence of faulting as interpreted from modeling of the observed resistivity data is therefore particularly significant since these structures may be the conduits for the thermal fluids. Sub-allurial fault zones are interpreted to occur between stations 0 to 5 NW on Line D and on Line A between stations 4 NW and 4 SE. Fault zones are also interpreted on Line C near stations 1 NW, 1 SE, and 3 SE, and on Line E between stations 2 to 4 NW and near 1 SE. No faulting is evident under the alluvial cover on the southwest end of Line B. A deep conductive zone is noted within the mountain range on two resistivity lines. There is no definite indication that thermal fluids are associated with this resistivity feature; DOE/ID/12079-11; ESL-41 Title: Interpretation of a dipole-dipole electrical resistivity survey, Colado geothermal area, Pershing County, Nevada Author: Mackelprang, C.E. Year: 1980 An electrical resistivity survey in the Colado geothermal area, Pershing County, Nevada has defined areas of low resistivity on each of five lines surveyed. Some of these areas appear to be fault controlled. Thermal fluids encountered in several drill holes support the assumption that the hot fluids may be associated with areas of low resistivity. The evidence of faulting as interpreted from modeling of the observed resistivity data is therefore particularly significant since these structures may be the conduits for the thermal fluids. Sub-allurial fault zones are interpreted to occur between stations 0 to 5 NW on Line D and on Line A between stations 4 NW and 4 SE. Fault zones are also interpreted on Line C near stations 1 NW, 1 SE, and 3 SE, and on Line E between stations 2 to 4 NW and near 1 SE. No faulting is evident under the alluvial cover on the southwest end of Line B. A deep conductive zone is noted within the mountain range on two resistivity lines. There is no definite indication that thermal fluids are associated with this resistivity feature; DOE/ID/12079-11; ESL-41 Close

• 3. [Image] Geochemistry of the Colado geothermal area, Pershing County, Nevada

  	Multielement geochemical analysis of drill cuttings from 18 shallow and 2 intermediate-depth temperature gradient holes outlines an area of anomalous geochemistry related to the fluid flow and temperature ...
  	Citation × Citation Citation Abstract Copy Title: Geochemistry of the Colado geothermal area, Pershing County, Nevada Author: Christensen, O.D. Year: 1980 Multielement geochemical analysis of drill cuttings from 18 shallow and 2 intermediate-depth temperature gradient holes outlines an area of anomalous geochemistry related to the fluid flow and temperature distribution within the Colado geothermal area. The concentrations of Hg, As, Li, and Be belong to more than one statistical population and provide the clearest expression of hydrothermal processes. Enrichments of these four elements define anomalous zones which are spatially coincident with a measured temperature anomaly. The spatial distribution suggests that thermal fluid rises into alluvium in the vicinity of a major Basin and Range fault to depths of 200 to 400 feet (60 to 120 m), then flows laterally within shallow alluvial aquifers down the local hydrologic gradient. As the fluid cools, Li, Be, As, and Hg are deposited in response to changing physical and chemical conditions. As and Be appear to be deposited early in higher temperature zones; Li begins to deposit early but forms a rather dispersed geochemical anomaly; Hg is anomalous throughout the entire geothermal area but is concentrated in a shallow halo above the As and Be anomalies. The distributions suggest that the entry of thermal fluids from depth into the alluvium is spatially restricted to a small area and that the larger area of the observed thermal anomaly is due to the flow of warm fluid within shallow aquifers; DOE/ID/12079-9; ESL-39 Title: Geochemistry of the Colado geothermal area, Pershing County, Nevada Author: Christensen, O.D. Year: 1980 Multielement geochemical analysis of drill cuttings from 18 shallow and 2 intermediate-depth temperature gradient holes outlines an area of anomalous geochemistry related to the fluid flow and temperature distribution within the Colado geothermal area. The concentrations of Hg, As, Li, and Be belong to more than one statistical population and provide the clearest expression of hydrothermal processes. Enrichments of these four elements define anomalous zones which are spatially coincident with a measured temperature anomaly. The spatial distribution suggests that thermal fluid rises into alluvium in the vicinity of a major Basin and Range fault to depths of 200 to 400 feet (60 to 120 m), then flows laterally within shallow alluvial aquifers down the local hydrologic gradient. As the fluid cools, Li, Be, As, and Hg are deposited in response to changing physical and chemical conditions. As and Be appear to be deposited early in higher temperature zones; Li begins to deposit early but forms a rather dispersed geochemical anomaly; Hg is anomalous throughout the entire geothermal area but is concentrated in a shallow halo above the As and Be anomalies. The distributions suggest that the entry of thermal fluids from depth into the alluvium is spatially restricted to a small area and that the larger area of the observed thermal anomaly is due to the flow of warm fluid within shallow aquifers; DOE/ID/12079-9; ESL-39 Close

• 4. [Image] Geology of the Colado Geothermal Area, Pershing County, Nevada

  	The Colado geothermal area in south-central Pershing County, Nevada is defined by hot water wells in alluvium just west of the West Humboldt Range. Geothermal gradient holes have encountered temperatures ...
  	Citation × Citation Citation Abstract Copy Title: Geology of the Colado Geothermal Area, Pershing County, Nevada Author: Sibbett, B.S. Year: 1980 The Colado geothermal area in south-central Pershing County, Nevada is defined by hot water wells in alluvium just west of the West Humboldt Range. Geothermal gradient holes have encountered temperatures up to 113.5/sup 0/C at a depth of 76 m (250 ft) with a gradient reversal in the alluvium below this depth. The West Humboldt Range consists mainly of Triassic to Jurassic slaty shale to quartzite of the Auld Lang Syne Group. Carbonate rocks of the Jurassic Lovelock Formation have been thrust over pelitic rocks on the south end of the area. Erosional remnants of Tertiary tuffs and sediments overlay the metasediments in the West Humboldt Range. The principal structures are high-angle faults striking north-northwest, northeast and north-south. The horst-to-graben transition along the range front consists of several step faults trending irregularly north. The structural pattern in the west edge of the range probably continues to the west under the Quaterary alluvium where the source of the hot water is located. Thermal waters probably rise along a major fault intersection in the Mesozoic rocks then spread out in an aquifer in the alluvium. Several thrust faults are exposed south of Coal Canyon, and a structural break in the Mesozoic rock exists under the canyon. Several low-angle faults are present north of Coal Canyon but their effect, if any, on the geothermal occurrence is not known; DOE/ID/12079-8; ESL-38 Title: Geology of the Colado Geothermal Area, Pershing County, Nevada Author: Sibbett, B.S. Year: 1980 The Colado geothermal area in south-central Pershing County, Nevada is defined by hot water wells in alluvium just west of the West Humboldt Range. Geothermal gradient holes have encountered temperatures up to 113.5/sup 0/C at a depth of 76 m (250 ft) with a gradient reversal in the alluvium below this depth. The West Humboldt Range consists mainly of Triassic to Jurassic slaty shale to quartzite of the Auld Lang Syne Group. Carbonate rocks of the Jurassic Lovelock Formation have been thrust over pelitic rocks on the south end of the area. Erosional remnants of Tertiary tuffs and sediments overlay the metasediments in the West Humboldt Range. The principal structures are high-angle faults striking north-northwest, northeast and north-south. The horst-to-graben transition along the range front consists of several step faults trending irregularly north. The structural pattern in the west edge of the range probably continues to the west under the Quaterary alluvium where the source of the hot water is located. Thermal waters probably rise along a major fault intersection in the Mesozoic rocks then spread out in an aquifer in the alluvium. Several thrust faults are exposed south of Coal Canyon, and a structural break in the Mesozoic rock exists under the canyon. Several low-angle faults are present north of Coal Canyon but their effect, if any, on the geothermal occurrence is not known; DOE/ID/12079-8; ESL-38 Close

• 5. [Image] Proceedings of the Seminar on Geothermal Energy, October 18-19, 1977, Hilo, Hawaii

  	Ten papers are included. Each was abstracted and indexed individually for EDB/ERA. Seven of the papers are included in Energy Abstracts for Policy Analysis (EAPA). (JGB)
  	Citation × Citation Citation Abstract Copy Title: Proceedings of the Seminar on Geothermal Energy, October 18-19, 1977, Hilo, Hawaii Author: Hawaii County Department of Research and Development Year: 1977 Ten papers are included. Each was abstracted and indexed individually for EDB/ERA. Seven of the papers are included in Energy Abstracts for Policy Analysis (EAPA). (JGB) Title: Proceedings of the Seminar on Geothermal Energy, October 18-19, 1977, Hilo, Hawaii Author: Hawaii County Department of Research and Development Year: 1977 Ten papers are included. Each was abstracted and indexed individually for EDB/ERA. Seven of the papers are included in Energy Abstracts for Policy Analysis (EAPA). (JGB) Close

• 6. [Image] Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California

  	A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent ...
  	Citation × Citation Citation Abstract Copy Title: Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent associated with the geothermal system at Coso. The boundaries of this low are generally well defined to the north and west but not as well to the south where an approximate southern limit has been determined. The bedrock resistivity low merges with an observed resistivity low over gravel fill east of Coso Hot Springs. A complex horizontal and vertical resistivity structure of the surveyed area has been defined which precludes the use of layered-earth or two-dimensional interpretive models for much of the surveyed area. In general the survey data indicate that a 10 to 20 ohm-meter zone extends from near surface to a depth greater than 750 meters within the geothermal system. This zone is bordered to the north and west by bedrock resistivities greater than 200 ohm-meters and to the south by bedrock resistivities greater than 50 ohm-meters. A combination of observed increases in: (1) fracture density (higher permeability), (2) alteration (high clay content), and (3) temperatures (higher dissolved solid content of ground water) within the bedrock low explain its presence Title: Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent associated with the geothermal system at Coso. The boundaries of this low are generally well defined to the north and west but not as well to the south where an approximate southern limit has been determined. The bedrock resistivity low merges with an observed resistivity low over gravel fill east of Coso Hot Springs. A complex horizontal and vertical resistivity structure of the surveyed area has been defined which precludes the use of layered-earth or two-dimensional interpretive models for much of the surveyed area. In general the survey data indicate that a 10 to 20 ohm-meter zone extends from near surface to a depth greater than 750 meters within the geothermal system. This zone is bordered to the north and west by bedrock resistivities greater than 200 ohm-meters and to the south by bedrock resistivities greater than 50 ohm-meters. A combination of observed increases in: (1) fracture density (higher permeability), (2) alteration (high clay content), and (3) temperatures (higher dissolved solid content of ground water) within the bedrock low explain its presence Close

• 7. [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 acoustics 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 acoustics 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

• 8. [Image] Potential of Low-Temperature Geothermal Resources in Northern California. Report No. TR13

  	Economically feasible uses for geothermal heat at temperatures too low for conventional electrical power generation at present are delineated. Several geothermal resource areas in northern California that ...
  	Citation × Citation Citation Abstract Copy Title: Potential of Low-Temperature Geothermal Resources in Northern California. Report No. TR13 Author: Hannah, J.L. Year: 1975 Economically feasible uses for geothermal heat at temperatures too low for conventional electrical power generation at present are delineated. Several geothermal resource areas in northern California that have development potential are described, and applications of the heat found in each area are suggested. Plates are included of the following field study areas: the east side of the Sierra-Cascade Range north of Bishop, and the northern Coast Range from San Francisco Bay to Clear Lake. The counties included in the study area are Mo doc, Lassen, Sierra, Plumas, Placer, Alpine, Mono, Mendocino, Lake, and Sonoma. (LBS) Title: Potential of Low-Temperature Geothermal Resources in Northern California. Report No. TR13 Author: Hannah, J.L. Year: 1975 Economically feasible uses for geothermal heat at temperatures too low for conventional electrical power generation at present are delineated. Several geothermal resource areas in northern California that have development potential are described, and applications of the heat found in each area are suggested. Plates are included of the following field study areas: the east side of the Sierra-Cascade Range north of Bishop, and the northern Coast Range from San Francisco Bay to Clear Lake. The counties included in the study area are Mo doc, Lassen, Sierra, Plumas, Placer, Alpine, Mono, Mendocino, Lake, and Sonoma. (LBS) Close

• 9. [Image] Assessment of geothermal resources of Caliente, Nevada

  	An assessment of the geothermal resources of Caliente, Nevada was made to provide information on resource characteristics and to site 2 (two) 500 ft (152 m) test wells to confirm the resource. The strategy ...
  	Citation × Citation Citation Abstract Copy Title: Assessment of geothermal resources of Caliente, Nevada Author: Trexler, D.T. Year: 1980 An assessment of the geothermal resources of Caliente, Nevada was made to provide information on resource characteristics and to site 2 (two) 500 ft (152 m) test wells to confirm the resource. The strategy used in the resource assessment employed a logical sequence of work elements that included 1) baseline data collection, 2) field investigations, 3) laboratory analyses and 4) data interpretation and synthesis. Airphoto interpretation indicated that a series of normal faults produced a stepped arrangement in the canyon walls on the west side of Meadow Valley Wash north of downtown Caiente. This area coincides with the area of known geothermal occurrences. Temperature measurements in existing wells indicate a rapid cooling of the geothermal waters as they mix with cold groundwater flows in Meadow Valley Wash. Soil mercury analyses range from 15 ppB to as high as 120 ppB. Trends in soil mercury content may indicate the presence of buried faults. Temperature measured in 2-meter deep auger holes indicated temperatures as high as 40/sup 0/C in an area north of the Lincoln County Medical Facility. Interpretation of chemical analyses, both major and minor, of waters collected from wells and streams in the area failed to conclusively show any mechanisms for the mixing of thermal and nonthermal waters. The selection of sites for the 2 (two) 500 ft (152 m) reservoir confirmation wells was made using the results of temperature surveys, geologic structure and historic observations; DOE/NV/10039-1 Title: Assessment of geothermal resources of Caliente, Nevada Author: Trexler, D.T. Year: 1980 An assessment of the geothermal resources of Caliente, Nevada was made to provide information on resource characteristics and to site 2 (two) 500 ft (152 m) test wells to confirm the resource. The strategy used in the resource assessment employed a logical sequence of work elements that included 1) baseline data collection, 2) field investigations, 3) laboratory analyses and 4) data interpretation and synthesis. Airphoto interpretation indicated that a series of normal faults produced a stepped arrangement in the canyon walls on the west side of Meadow Valley Wash north of downtown Caiente. This area coincides with the area of known geothermal occurrences. Temperature measurements in existing wells indicate a rapid cooling of the geothermal waters as they mix with cold groundwater flows in Meadow Valley Wash. Soil mercury analyses range from 15 ppB to as high as 120 ppB. Trends in soil mercury content may indicate the presence of buried faults. Temperature measured in 2-meter deep auger holes indicated temperatures as high as 40/sup 0/C in an area north of the Lincoln County Medical Facility. Interpretation of chemical analyses, both major and minor, of waters collected from wells and streams in the area failed to conclusively show any mechanisms for the mixing of thermal and nonthermal waters. The selection of sites for the 2 (two) 500 ft (152 m) reservoir confirmation wells was made using the results of temperature surveys, geologic structure and historic observations; DOE/NV/10039-1 Close

• 10. [Image] Delineation of an electrical resistivity anomaly, Malpais area, Beowawe KGRA, Eureka and Lander Counties, Nevada

  	A simple numerical model of previously released bipole-dipole resistivity data shows the margin of the graben to be anomalously conductive below the Malpais. The conductive area has been delineated with ...
  	Citation × Citation Citation Abstract Copy Title: Delineation of an electrical resistivity anomaly, Malpais area, Beowawe KGRA, Eureka and Lander Counties, Nevada Author: Smith, C. Year: 1980 A simple numerical model of previously released bipole-dipole resistivity data shows the margin of the graben to be anomalously conductive below the Malpais. The conductive area has been delineated with data from a dipole-dipole resistivity survey run in April 1980 for this study. Detailed numerical models of these data define a 1250 m wide body with resistivities less than 20 ohm-m that appear to connect The Geysers and the graben boundary. The minimum depth to the conductor is interpreted to be 375 m; its depth extent is undetermined. The electrical data do not resolve whether the anomaly below the Malpais may be the product of a defunct hydrothermal system or the signature of an active system. If thermal gradient data detect an enhanced heat flow anomaly in the same area, the Malpais may be a viable geothermal exploration target within the Beowawe KGRA; DOE/ID/12079-7 Title: Delineation of an electrical resistivity anomaly, Malpais area, Beowawe KGRA, Eureka and Lander Counties, Nevada Author: Smith, C. Year: 1980 A simple numerical model of previously released bipole-dipole resistivity data shows the margin of the graben to be anomalously conductive below the Malpais. The conductive area has been delineated with data from a dipole-dipole resistivity survey run in April 1980 for this study. Detailed numerical models of these data define a 1250 m wide body with resistivities less than 20 ohm-m that appear to connect The Geysers and the graben boundary. The minimum depth to the conductor is interpreted to be 375 m; its depth extent is undetermined. The electrical data do not resolve whether the anomaly below the Malpais may be the product of a defunct hydrothermal system or the signature of an active system. If thermal gradient data detect an enhanced heat flow anomaly in the same area, the Malpais may be a viable geothermal exploration target within the Beowawe KGRA; DOE/ID/12079-7 Close