摘要
? This paper presents a brief analysis of the geothermal fields of Meso-Cenozoic basins and their evolution in East China by means of heat flow, geotemperature gradient, vitrinite reflectence and its gradient in the basins, and reveals a basic framework of the geothermal regime of the basins. The geothermal regime of Meso-Cenozioc basins in East China is mainly dominated by tectonic conditions. The important factor determining the geothermal state of basins is the thickness of lithosphere—burial depth of asthenospheric top, which is related to geodynamic type of basins. Basins in the western zone, represented by Sichuan and Ordos, belong to the flexure basins on the basement of continental block, with thick lithosphere, generally 120-150 km. All basins in this zone fall into middle heat basin type in the light of their lower ancient and present geotemperature gradient. While the middle zone is represented by Songliao and Bohaiwan basins, the continental margin zone is represented by East China Sea shelf basin and northern continental shelf basins of South China Sea. They belong to the extensional basins with thinning lithosphere, the smallest burial depth of paleoasthenospheric top, being 55-60 km. Therefore they should belong to heat basin type. The geothermal state of the basins is correlated positively with extension degree in the majority of basins controlled by dynamic mechanism of extension and transtension.
? This paper presents a brief analysis of the geothermal fields of Meso-Cenozoic basins and their evolution in East China by means of heat flow, geotemperature gradient, vitrinite reflectence and its gradient in the basins, and reveals a basic framework of the geothermal regime of the basins. The geothermal regime of Meso-Cenozioc basins in East China is mainly dominated by tectonic conditions. The important factor determining the geothermal state of basins is the thickness of lithosphere—burial depth of asthenospheric top, which is related to geodynamic type of basins. Basins in the western zone, represented by Sichuan and Ordos, belong to the flexure basins on the basement of continental block, with thick lithosphere, generally 120-150 km. All basins in this zone fall into middle heat basin type in the light of their lower ancient and present geotemperature gradient. While the middle zone is represented by Songliao and Bohaiwan basins, the continental margin zone is represented by East China Sea shelf basin and northern continental shelf basins of South China Sea. They belong to the extensional basins with thinning lithosphere, the smallest burial depth of paleoasthenospheric top, being 55-60 km. Therefore they should belong to heat basin type. The geothermal state of the basins is correlated positively with extension degree in the majority of basins controlled by dynamic mechanism of extension and transtension.
