Abstract:

Based on Prof.Zhu Xia's theory of double classification of oil-and gas-bearing basin,the authors studied the evolution stacking and hydrocarbon potential of the Ordos Basin.The basin has experienced several development stages in tectonic evolution,there were a number of basin prototypes.During the Middle Proterozoic,thereexisted a series of aulacogens within the craton,then they changed into anunified syneclise.In the Early Paleozoic,regenerated aulacogens could onlybe found in the western margin of the basin while the main part of it was occupied by craton depression.Although the whole of the North China was uplifted and denuded by the Caledonian Movement,the inside of Ordos continuedto develop craton depression,only a collision valley of the Middle and Late Carboniferous was formed in the north part of the western margin of it.The Permian and Early-Middle Triassic were a transitional period in its evolutionhistory.In this period,structural differentiations were closed and a unified sedimentary environment was formed.From the Late Triassic on,a differential subsided basin was formed by push-compression stress of the peripheral struc-tures in the Ordos and the broad North China region,only the western marginof it developed into a front depressed basin on the move from west to east.Fromthe Cenozoic,the whole of the Ordos uplifted,only some fault-depressedbasins were formed by regional strike-slip faults outside the Ordos.Oil potential of the Ordos Basin is characterized by multi-sequence gene-ration,multicycle accumulation,multi-type traps and broad distribution.Thepivotal zone and overthrust nappe belts on the west margin may possibly be hy-drocarbon enriching zones.