| Abstract |
About 300 square kilometers of Pai district is occupied by large pluton of granite which is predominantly coarse grained biotite granite of Triassic age. The main joint patterns of granitic body lie in NNE, NE, EW and NNW trending, having the appropriate permeability for hot fluid ascending to the surface in some geothernial areas i.e. Ban Pong Mai (MHq) , Ban Muang Rae (MHg) and Huai Muang Paeng (ma). The other thermal areas i.e. Pong Sak (MH3), Pong Pa (MH5) , Ban Mae Na (MH7), Ban Mae He (M H l o ) and Pong Jaja (MH14) are associated with semimentary rock and low-grade metamorphic rock of Paleozoic Era. These Paleozoic rocks which exposed around the granitic batholith are composed of Cambrian quartzite; Ordovician limestone; low-grade metamorphic rocks of Silurian- Devonian age; conglomerate, sandstone, siltstone and shale in Carboniferous and Permian limestone. Tertiary beds exposed locally along the edge of Pai Basin which is also filled by Quaternary sediments. Old basic volcanic rock locally distri5utes and mostly found underlain the Permian limestone. Joint systems of the geothermal areas found in Paleozoic rock are resemble with those found in Triassic granite. |