High-Temperature Geothermal Source in the Northeastern Datong Basin, North China: Evidence from the Drilled Rhyolite

We have identified the rhyolitic samples from the HT geothermal drillhole KT-8 in the Tianzhen area, northeastern Datong Basin. Such rock consists of phenocryst grain of quartz, perthite, and biotite with minor volcanic glass. The geothermometer of ternary-feldspar yields the crystallized temperatures ranging from 600 to 800 °C with average value of 700 °C, representing the crystallized temperature of rhyolitic magma. According to major and trace element characteristics as well as Sr-Nd isotope, such magma likely derived from partial melting of Archean gneissic complexes that was triggered by the segregation of mantle-derived basalts in the studying area. The magmatic evolution is important link between deeply magmatic source and shallow volcanic activity. Combined with tectonic background and geothermal investigation, the rhyolite and its surrounding gneissic complexes would be as the source and reservoir for the HT geothermal system in the Tianzhen area, respectively. The final publication is available at Springer via https://doi.org/10.1007/s12583-024-0035-y.