Study on Deep Geothermal Geological Conditions in Hainan Island, China

ABSTRACT: Hainan Island is located in the south of Chinese Mainland in geography, and is located in the Cathaysia block in the south of South China plate in tectonics, which is adjacent to the West Pacific tectonic domain in the east. Previous studies have discovered 46 geothermal fields and hot springs. Studying the geological background and genesis of its distribution is of great significance for understanding the occurrence laws, exploration, and development of geothermal resources. This article conducts a regional geological survey and uses geological, geophysical, geochemical, petrological, and structural geological methods to comprehensively study the geological conditions for the formation of deep geothermal resources in Hainan Island. The research results indicate that the heat source in Hainan Island mainly comes from mantle source conduction and granite radioactive heat generation. The weathering crust on the top of the Hercynian to Indosinian granite buried at a depth of 3-5 km is the highest quality geothermal reservoir type in the area. The overlying Neogene and Cretaceous sediments are high-quality cover layers. The east-west and northwest southeast deep faults are the main thermal conduction channels. The northern Fushan Depression and the central Baisha Basin, Yangjiang Basin, Leiming Basin, and Wangwu Basin are prospective areas for deep geothermal enrichment.