Abstract:

Most sedimentary basins in China belong to superimposed basins,their palaeogeothermal fields were generally reformed or changed.According to different reformation types of palaeogeothermal fields,the reformations can been classified into deep buried reformation,thermal event reformation and stress reformation.Because of differences in regional geology background and evolution history,there were greater differences in palaeogeothermal fields of the basins in North China.North China Basin and Tarim Basin were located in stable craton in Paleozoic,and characterized by stable sedimentary structures,and low geothermal gradients;Turpan-Harmi Basin and Junggar Basin were located in Hasakestain Plate,underwent fault subsidence and strong tectonic activities,and their geothermal gradients were high.Geothermal gradients of the basins in the eastern of Algin Rift were higher than those of the basins in western of Algin Rift in Late Mesozoic,and tectonic activities were stronger,indicating a strong regional tectonic thermal event.The basins on the western of Algin Rift were all compressive depressions,their geothermal gradients were lower.Sine Cenozoic,the eastern region of China has been in stretching background,geothermal gradient and heat flow are high in the basins;the west part of China has been in the crust compression and thickening background,geothermal gradient and heat flow are lower in the basins.

Key words: North China, sedimentary basin, tectonic geothermal event, palaeothermal gradient, thermal evolution history, reformation