GEOTHERMAL FIELD DISTRIBUTION IN CHINA AND ADJACENT SEA AREAS

On the basis of measurements of the temperatures of hot springs,earth surface and wells and heat flow in lakes and seas, a geothermal field information map of China and adjacent sea areas have been compiled.In the map China is di vided into eight geothermal regions.According to these data combined with related geophysical data, some views are proposed about the geothermal field distribution and evolution of crustal structure. A lot of geotherma activities and high heat flow values show that the crust of the Xizang（Tibet）geothermal region is in a hot state,with local shallow molten masses.Absorption of seimic waves,negative magnetic anomalies and MT anomalous zones at depths of 10—20km all support the hypothesis. The North China geothermal region is large Meso—Cenozoic subsidence basin.As it experienced a rift development stage,its local geothermal background is higher.Local hot points appear at places where the crust becomes thin and Ourie isothermal surface becomes shallow. The crust of the Taiwan and East China Sea geothermal is fairly thin（20—30）km and fractures are well developed.This faciliates the ascent of hot fluids and gives rise to middle-low temperature hydrothermal activity. The heat flow data from the South China Sea（average 2.08 HFU）show that there is no subduction zone between the continental slope and the deep sea basin and that in stead passive continental margins may possibly exist. Greadual thickening of China’s crust from east to west may explains a decrease in geothermal gradient from east to west. In the end the paper discusses the relationships between the geothermal regions and the development of geothermal resources and oil prospects.