Abstract: In order to study the characteristics of Lower Cretaceous source rocks and shale gas exploration potential of the eastern basin group in Northeast China,field sampling,geochemical analysis and rock-mineral tests of source rocks were performed and geochemical parameters were measured in the Sanjiang Basin,Jixi Basin,Tonghua Basin,Liuhe Basin and Hongmiaozi Basin.The results indicate that the abundance and type of organic matter in the Lower Cretaceous source rocks are mainly controlled by sedimentary facies,while the maturity of source rocks is influenced by the depth of Moho surface.The Lower Cretaceous source rocks in the north of the study area were deposited in shallow water environment that results in large cumulative thickness of mudstones and higher silt content.These source rocks contain type Ⅱ₂ kerogen and Ⅲ kerogen and are graded as poor-moderate source rocks at mature to over-mature stages.The Lower Cretaceous source rocks in the south of the study area were deposited in deeper water environment that results in thick mudstone deposition (with thickness of 233 m to 446 m) and high organic content.These source rocks mainly contain type Ⅰ-Ⅱ₂ kerogen at low-mature to mature stages.Moreover,the Lower Cretaceous hydrocarbon source rocks are characterized by high content of brittle minerals,important content for development of pores and fractures between clay minerals,intergranular pores as well as organic pores with pore throat structure of micro- and meso-pore.Therefore,there exists favorable exploration prospects for both conventional hydrocarbon and shale gas in Lower Cretaceous of eastern basin group in Northeast China.

Key words: Moho surface, organic pore, source rock, shale gas, Lower Cretaceous, eastern basin group