1. College of Earth Sciences��Jilin University��Changchun 130061��China; 2. Key- Laboratory for Oil Shale and Coexisting Minerals��Jilin University��Changchun 130061��China

According to the core observation�� geochemical analysis and maceral identification�� we indicate the law of the organic matter evolution in the first member of Qingshankou Formation by the Well NGN1�� The Well NGN1 is located in the southeast of Songliao Basin�� There is gray- green argillaceous siltstone- dark gray shale��oil shale- gray mudstone- gray- green silty mudstone from bottom to top in the first member of Qingshankou Formation�� It reveals that the evolvement of sedimentary environment is from shallow lake to semi- deep lake to shallow lake�� TOC��S 2 ��FA and HI show the increase- a high value- decrease trend��and semi- coke content and bulk density are showing the opposite trend�� By the maceral identification of oil shale polishsection�� the main organic maceral are la- malginite��sporinite and fish bone�� The maceral identification shows that the organic matter content has a positive correlation with the relative content of macersl and algae components per unit area�� Combined with organic discrimi- nation diagrams�� it is explained that the organic matter type is mainly type I and II 1 �� and the main source of organic matter is lake algae�� Terrestrial organic matter content is very little in the mudstone��so it illustrates that the lake biology is the organic matter sources�� The poor storage conditions of the shallow lake lead to lower abundance of or- ganic matter in mudstone�� The good preservation conditions of semi- deep lake and deep lake promote the enrich- ment of organic matter�� Therefore�� sedimentary environment evolution is the main factor of the change of the organic matter in vertical direction��