Genetic model of intraplate volcanic high-temperature geothermal system in Yanggao-Tianzhen Basin, Datong

The Yanggao-Tianzhen Basin comprises three stratigraphic sequences from top to bottom, namely the Quaternary, Neogene-Paleogene, and Archean. The Quaternary serves as the regional caprock, and heat transfer within the basin occurs primarily via thermal conduction, with a higher geothermal gradient in the eastern part than in the west. Heat sources are distributed in the northern and eastern regions at a burial depth ranging from 4000 to 8000 m. Shallow-buried heat sources dominate the western part, while the eastern part features distinct magmatic channels connecting to shallow strata. The main fault system in the basin, trending NE-SW, provides pathways for deep heat sources. Unerupted concealed volcanic clusters are mainly distributed in the Yanggao area (central basin), consistent with the basin's structural strike; in contrast, concealed volcanic craters in the Tianzhen area are scattered in isolation, with visible magmatic channels. The hydrochemical type of shallow geothermal water is HCO₃-Ca·Mg, while that of deep geothermal water is HCO₃·Cl·SO₄-Na. Geothermal water originates from atmospheric precipitation and exhibits poor circulation and renewal conditions. The formation and distribution of intraplate volcanic high-temperature geothermal resources are controlled by the combination of concealed volcanic distribution and deep/large faults. By characterizing the spatial structure of unerupted concealed volcanoes as well as the dynamic processes of heat conduction in the fault system and hydrothermal circulation, we propose a trinity genetic model of “magmatic heat source - structural conduction - shallow local thermal anomaly”. Moreover, it is believed that the intraplate high-temperature geothermal system is activated and formed due to the long-range effect of plate subduction and collision caused by the “modification of supergene structures by deep processes".