Petrologic considerations for hot dry rock geothermal site selection in the Clear Lake Region, California

Conference · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7309591

Stimac, J; Goff, F ^[1]; Hearn, Jr, B C ^[2]

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1. Los Alamos National Lab., NM (United States)
2. US Geological Survey, Reston, VA, Branch of Lithospheric Processes (United States)

The Clear Lake area is well known for anomalous heat flow, thermal springs, hydrothermal mineral deposits, and Quaternary volcanism. These factors, along with the apparent lack of a large reservoir of geothermal fluid north of Collayomi fault make the Clear Lake area an attractive target for hot dry rock (HDR) geothermal development. Petrologic considerations provide some constraints on site selection for HDR development. Spatial and temporal trends in volcanism in the Coast Ranges indicate that magmatism has migrated to the north with time, paralleling passage of the Mendocino triple junction and propagation of the San Andreas fault. Volcanism in the region may have resulted from upwelling of hot asthenosphere along the southern margin of the subducted segment of the Gorda plate. Spatial and temporal trends of volcanism within the Clear Lake volcanic field are similar to larger-scale trends of Neogene volcanism in the Cost Ranges. Volcanism (especially for silicic compositions) shows a general migration to the north over the {approximately}2 Ma history of the field, with the youngest two silicic centers located at Mt. Konocti and Borax Lake. The Mt. Konocti system (active from {approximately} 0.6 to 0.3 Ma) was large and long-lived, whereas the Borax Lake system is much smaller but younger (0.09 Ma). Remnants of silicic magma bodies under Mt. Konocti may be in the latter stages of cooling, whereas a magma body centered under Borax Lake may be in the early stages of development. The existence of an upper crustal silicic magma body of under Borax Lake has yet to be demonstrated by passive geophysics, however, subsurface temperatures in the area as high (> 200{degrees}C at 2000 m) as those beneath the Mt. Konocti area. Based on petrologic considerations alone, the Mt. Konocti-Borax Lake area appears to be the most logical choice for HDR geothermal development in the region.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 7309591
• Report Number(s): LA-UR-92-1492; CONF-921083-3; ON: DE92015206
• Resource Relation: Conference: Geothermal resources council meeting, San Diego, CA (United States), 4-7 Oct 1992; Other Information: PBD: [1992]
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
DIKES
FLOW MODELS
HOT-DRY-ROCK SYSTEMS
PETROLOGY
LAVA
CALIFORNIA
GEOLOGIC FAULTS
GEOLOGIC MODELS
GEOLOGY
GEOTHERMAL FIELDS
GEOTHERMAL FLUIDS
HEAT FLOW
HISTORICAL ASPECTS
MAGMA SYSTEMS
RESOURCE DEVELOPMENT
SPATIAL DISTRIBUTION
TECTONICS
VOLCANISM
DEVELOPED COUNTRIES
DISTRIBUTION
FLUIDS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOTHERMAL SYSTEMS
MATHEMATICAL MODELS
NORTH AMERICA
USA
Geothermal Legacy
150200* - Geology & Hydrology of Geothermal Systems
580000 - Geosciences