Alteration Age and Heat Source Rock in the Hohi Geothermal Area, Japan, in Relation to 'Geothermal Index'
- Key words
- alteration age, heat source rock, Hohi geotermal area, geothermal index
- Location
- Hohi, Japan
- Conference
- World Geothermal Congress
- Year
- 2000
- Session
- Exploration and Development
- Language
- English
- Paper number
- R0674
Full text
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Abstract
In order to relate underground temperature to age of altered and volcanic rocks at the surface, TL and FT datings have been carried out on zircon from the Hohi geothermal area. Depthtemperature curves of wells drilled in the area were evaluated using ìGeothermal Index (GI)î, which ranges from 0 to 100 and is higher than 35 for steam-productive wells. In most cases, they are accompanied by volcano younger than 300Ka, and/or altered rock younger than 50Ka, within the circular area whose radius is equal to their depths. The heat source volcano tends to have larger ratios of diameter to height, suggesting higher viscosity of its magma, which may emplace at shallower depths acting as heat source.
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