AN APPROACH TO THE DETERMINATION OF PALEOGEOTHERMAL GRADIENT BY FLUID INCLUSIONS——A CASE STUDY OF THE NORTH JIANGSU BASIN
TAN Cai-ping(Wuxi Research Institute of Experimental Geology, SINOPEC,Wuxi, Jiangsu 214151, China)
The sedimentation and diagenesis of clastic rocks are accompanied by crystallization and grain secondary enlargement. During the crystallization and growth of mineral, the liquid in clastic rock pores is trapped in the crystal defects and holes, lattice vacancy and dislocation and microfissures of mineral to form fluid inclusions. Using the thermometric data of inclusions, the paleogeotemperature for each geologic ages of the sedimentary basin is determined, and the paleogeothermal gradient is calculated. They reflect the evolutionary situation of paleogeotemperature in the geologic history of the sedimentary basin. It was rea-lized from petroleum geological studies that kerogen changes into petroleum in the temperature of 60-150℃ and into natural gas in the temperuture of 150-200℃. Therefore, the reconstruction of paleogeotemperature and paleothermal gradient for the different historical periods of the sedimentary basin has very important significance for petroleum geological studies.
【CateGory Index】： P531