Fluid and Heat Sources in the Chingshui Geothermal System

Abstract

The Chingshui geothermal field is located in the valley of Chingshui stream, southwest of Ilan Plain, northeast Taiwan. The rock hosting the geothermal field is the Miocene Lushan Formation, consisting dominantly of argillite/slate with intercalated thin meta-sandstones. Several hot springs with minor hydrothermal alterations are the important thermal manifestations, which they crop out along the river bed and rock cliffs in this area. In this study, we combined the clumped isotopes with carbon and oxygen isotopic compositions of calcite scaling and veins from geothermal wells and outcrops, respectively, and geophysical information. Two hydrothermal reservoirs at different depths have been identified. The shallow reservoir provides the fluid from meteoric water for the scaling sampled from wells dominantly, while the deep reservoir provides magmatic fluid with deep marble decarbonization recorded in outcropping calcite veins.