San Kamphaeng geothermal field is one of the most promising and extensively studied areas in Thailand. Geological studies at scale 1:10, 000 indicate that the area is composed of the oldest Mae Tha Carboniferous Formation, the Middle Permian Kiu Lom Formation, Triassic granites and andesites, and alluvial deposits. The area is a horst-and-graben type bordered by normal faults, the Huai Pong fault and the Huai Mae Koen fault, both trending in a NNW-SSE direction. Otcropping chemical alteration zones indicate that the hydrothermal solution causing the alteration is possibly an intermediate-to-acidic liquid of less than 200°Cemperature. Chemical geother-mometer calcuations using the SiO
2 and the Na-K-Ca method yield reservoir temperatures of about 160°Cnd 192°Co 207°Cespectively, as confirmed by a 30 m depth temperature survey that reached a geothermal fluid portion of 139°CSeismic studies indicate that the faults along the hot spring area and adjacent area still active and the geothermal fluids circulate and flow up to the surface along these conduits. In conclusion, the potential geothermal area in the San Kamphaeng geothermal system is confined to the Ban Pong Nok District, where actual manifestations are found on the surface and N-S and NW-SE trending faults are present.
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