Depth to and concentrations of water in large bodies of silicic magma. Progress report, July 1, 1982-June 30, 1983

Technical Report · Thu Mar 03 04:00:00 EST 1983

DOI:https://doi.org/10.2172/6396386· OSTI ID:6396386

Anderson, A T

Large bodies of silicic magma are potential sources of geothermal energy and ore. They also pose threats of catastrophic eruptions. The depths of such bodies are related to their economic potential and probably to their eruption mechanisms. The concentrations of water in the magmas are important for their eruptive and dynamical behavior and for the development of ores. Estimates of viscosity and density of melt require knowledge of concentration of water. The concentration of water in melt before ascent and eruption can be measured in inclusions of glass which became trapped in crystals before extrusion. The depth of a magma body can be estimated or delimited if we can find out the concentrations of both carbon dioxide and water in the inclusions of glass. Initial results on the Bishop Tuff of Long Valley Caldera, California yield 4.9 +- 0.5 percent H/sub 2/O for glass included in quartz from the Plinian air fall pumice. This result is comparable to the estimates of Hildreth (1977) of about 3.5 to 4.9 percent H/sub 2/O in the lowermost part of the Bishop ash flow. From January 1982 through December 1982, analyses of inclusions of glass in two additional quartz phenocrysts from the Plinian air fall unit of the Bishop Tuff revealed variable H/sub 2/O and CO/sub 2/. The corresponding partial pressures range between about 2000 and 5000 atmospheres, assuming gas saturation. The variation may be natural or caused by an analytical artifact. A computerized data file has been constructed to facilitate the storage and retrieval of published and unpublished chemical analyses of glasses and minerals. Some data on the Bishop Tuff are presently stored.

• Research Organization: Chicago Univ., IL (USA)
• DOE Contract Number: AC02-80ER10763
• OSTI ID: 6396386
• Report Number(s): DOE/ER/10763-2; ON: DE83008082
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150201* -- Geology & Hydrology of Geothermal Systems-- USA-- (-1989)
152002 -- Geothermal Data & Theory-- Properties of Minerals & Rocks
CALIFORNIA
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
DEPTH
DIMENSIONS
FEDERAL REGION IX
GEOTHERMAL RESOURCES
GEOTHERMAL SYSTEMS
GLASS
Geothermal Legacy
HYDROGEN COMPOUNDS
HYDROLOGY
INCLUSIONS
LONG VALLEY
MAGMA
MAGMA SYSTEMS
MINERALS
MOISTURE
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PUMICE
QUARTZ
RESOURCES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
TUFF
USA
VISCOSITY
WATER