According to the molecular composition of bitumoids, extracted from the dispersed organic matter of rocks, occurring in the eastern territories of the Tomsk region, there were obtained the new data of the paleogeographic environments of sedimentation from the Early Jurassic to Late Cretaceous period, as well as the characteristic features of the organic matter composition in separate stratigraphic horizons and the organic matter thermal maturity. There was identified the oil-source strata, which generated the oil in Yuzhno-Pyzhinskaya area. A specific set of alkylbenzenes, being uncharacteristic of other parts of the section, was fixed in the organic matter of the Upper Jurassic sediments.