松辽盆地梨树断陷早白垩世微体古生物、沉积环境以及控油意义

根据松辽盆地梨树断陷早白垩世地层中孢粉百分含量的纵向变化特征,建立了自下而上各层组的孢粉组合。通过分析孢粉、藻类以及介形类的古环境指示特征,恢复了梨树断陷地层的气温带、古植被、干湿度以及湖水古盐度。沙河子组沉积时期为温暖潮湿的中亚热带气候,古植被为针叶林和灌草丛,湖水为淡水、微咸水;营城组沉积时期为南亚热带气候,古植被为针叶林和灌草丛,湖水同样为淡水、微咸水;到了登娄库组沉积时期,气候变得炎热干旱,为热带气候,古植被为针叶林,湖水则变为半咸水。本文的研究结果可以有效指示地层的划分与对比以及沉积环境的分析。同时,结合盆地发育讨论了古气候变化的控油意义,古气候的变化控制着烃源岩和储层的发育与分布。

ON THE MICROFOSSIL ASSEMBLAGES,PALEOCLIMATE INDICATOR AND OIL-CONTROLLING SIGNIFICANCE FROM THE LOWER CRETACEOUS STRATA IN THE LISHU DEPRESSION,SONGLIAO BASIN,NE CHINA

According to the distribution of the sporopollen components in the Lower Cretaceous strata from the Lishu fault depression of Songliao basin,sporopollen assemblages of each formations from bottom to top are identified.By analyzing the paleoenvironment indicators of sporopollen,algae and ostracods,the ancient vegetation zone,temperature,humidity and salinity are reconstructed in the Lishu depression.In the sedimentary period of the Shahezi Formation,it was a warm and humid subtropical climate,the main vegetation was coniferous forest and grass,and the lake water was fresh or brackish;in the sedimentary period of the Yingcheng Formation,it was a south Asian tropical climate,the vegetation was coniferous forest and grass,and water was also fresh and brackish.In the sedimentary period of the Denglouku Formation,the paleoclimate became hot and dry,which belongs to a tropical environment,the vegetation was coniferous forest,and water was brackish.This study provides a significant subdivision and correlation of stratigraphy,and analysis of sedimentary environment.In addition to the reconstruction of basin development,the paleoclimate change is discussed in this paper which implies their importance in controlling the oil-gas formation and preservation.