Abstract:

The formation and evolution of Huabei Basin is discussed in terms of sedimentary formation and tectonic cycle.Generally speaking,it has experienced two stages of development,i.e.,the stable platform of the Middle-Late Proterozoic to Palaeozoic,and the platform activization to block-faulted basin during Meso-Cenozoic Period.The stage of platform has gone through three evolution periods such as themarginal downwarp of platform in Middle-Late Proterozoic,stable platform basin in Early Palaeozoic and the alternated marine and nonmarine basin of Late Palaeozoic.The stage of block-faulted basin can be divided into sixevolution periods:(1)the Trassic uplifted platform resulted by the withdrawalof lacustrine basins,(2)the Early to Middle Jurassic fault-down warped basin,(3)the Late Jurassic-Early Cretaceous fault-fold basin,(4)the Late Cretaceous-Paleocene fault-uplift,(5)the Eocene-Oligocene fault-depressed basin and(6)the Tertiary-Quartery downwarped basin,The basins formed in these evolutionstages bare their own specialities in pattern,framework,sedimentation and formation mechanim.It is stressed by the author that 7 types of major oil generation fault-downwarp basins can be divided in the evolution process in Eocene-Oligocenewithin Huabei Basin.It is specific in southern,central and northern partsrespectively.They have different tectonic cycles,delay of formation and multiple assemblages of oil generation.Finally,the author suggests that the main task of oil exploration in Huabei Basin in recent years is to extend the exploration extent in Tertiary rocks,to start oil prospecting in Upper Palaeozoic-Mesozoic systems and to prepare for the exploration in Lower Palaeozoic.