GEOCHEMICAL CHARACTERISTICS OF JINZAI OIL-SOAKED SANDSTONE IN THE HEFEI BASIN

The macropetrology, organic petrology, organic geochemical characteristics and oil source of Jinzai oil-soaked sandstone in the Hefei Basin were studied in this paper. The oil-soaked sandstone, which was discovered in the Middle Jurassic Sanjianpu (J₂s) strata of the South Hefei Basin, is an arkose. Oil disseminates along microlayers (laminae) or bedding planes, and organic matter infills pores and fissures taking the shapes of dispersed bitumen or oil drops. Low content of organic carbon (C) and chloroform extracted bitumen "A" is related to hydrocarbon migration as well as the oxidation and biochemism subjected afterwards. The organic mother material, which is dominated by hydrobios and algae, belongs to the sapropel type and is lake deposit under reduction environment. The evolution of organic material has got to the mature stage, and the oil source may comes from the hydrocarbon source rock of the Sanjianpu Formation. So the Shucheng Depression is the favorable zone for the hydrocarbon exploration of teh Hefei Basin.