TECTONIC AND SEDIMENTARY FEATURES OF JURASSIC AND PETROLIFEROUS CHARACTER IN THE HEFEI BASIN

A series of parallel thrusting structural belts and foredeep basins were formed in the Hefei Basin of Mesozoic,affected by different stages compression and thrusting orogenesis of Yanshanian Mvt.1.Foredeep basin had both inheritance and rebirth in different stages,and structural extent gradually diminsh from south to north,then,Molasse formation was formed which was thick in south and thin in north in Jurassic of the Hefei Basin,and sediment of variegation sand-mudstone and gray-black carbonaceous-mudstone and thin coal layer of fluvial-plain marsh facies only grow on marginal slope of different stage basins.As Yangzi geological body thrust and squeeze toward north so as earth temperature is high regionality,and Jurassic accumulate quickly,source rocks of Palaeozoic reached overmature evolution stage during Jurassic in depression ,which is limited in producing hydrocarbon.