Progress in research on the exploration and evaluation of deep geothermal resources in the Fujian-Guangdong-Hainan region, China

Deep geothermal resources in the Fujian-Guangdong-Hainan region, China, offer significant potential for sustainable energy. The diverse igneous rock formations along the southeast coast present intricate geological challenges that impede exploration and evaluation efforts. In this study, we address critical concerns related to the Fujian-Guangdong-Hainan region's deep geothermal resources, encompassing heat source composition, formation conditions, strategic favorable areas, and exploration directions. Our methods involve the analysis of regional geothermal reservoirs and cap rocks. Major findings include: the primary heat sources in the Fujian-Guangdong-Hainan region consist of the radioactive heat generation from granites in the crust, heat conduction in the mantle, and, in specific areas like Yangjiang and Shantou, melts within the middle and lower crust; the deep, high-temperature geothermal resources in the region predominantly reside in basins' depressed areas. These areas are characterized by the confluence of triple heat sources: heat from the Earth's crust, mantle, and other supplementary sources; our analysis led to the identification of three strategic areas favorable for deep geothermal resources in the Fujian-Guangdong-Hainan region. These are the Beibu Gulf Basin's continental area, the Yuezhong Depression, and the Fuzhou-Zhangzhou area. [Display omitted] •Heat sources in the Fujian-Guangdong-Hainan region are analyzed.•Cenozoic sandstone, Mesozoic granite and Paleozoic limestone are the major geothermal reservoirs in the region.•Three potential zones of deep geothermal resources with strategic significance are predicted.