松辽盆地白垩纪微体生物群分布特征与富烃源岩层的形成

THE CHARACTERISTICS OF CRETACEOUS MICROBIOTAS AND FORMATION OF HYDROCARBON-RICH SOURCE ROCKS IN SONGLIAO BASIN

松辽盆地是我国白垩纪最大的陆相含油气盆地,晚白垩世两次大的湖侵事件导致了微体生物群的繁盛和富烃源岩层的形成。在论述松辽盆地白垩纪微体古生物群分布特征的基础上,着重阐述了以微体生物为核心的松花江生物群的发育与富烃源岩层形成的关系。认为大型富营养湖泊的发育为松花江生物群的繁盛创造了良好的外部条件,而湖盆内繁盛的微体生物群则为富烃源岩层的形成提供了丰厚的物质基础,与此同时,长期继承性深水构造凹陷和非补偿沉积则是富烃源岩层形成的有利场所。

The Songliao Basin is the largest continental sedimentary basin in Cretaceous, bearing rich oil and gas source. During the Late Cretaceous, two lake transgressions happened, and caused the prosperity of Songhuajiang Biota and formed the rich organic beds （including the first member of Qingshankou Formation and the first and second members of Nenjiang Formation）. Based on the characteristics of microbiotas in Cretaceous, this paper elaborated the relationship between the development of Songhuajiang Biota and hydrocarbon-rich source rocks. The large nourishment lake is a necessary exterior condition to the prosperity of Songhuajiang Biota, and the microfossils provided abundant material foundation to the accumulation of source rocks. The long-term inheriting of deep-water depression with non-compensate sedimentary is the beneficial place for the preservation of rich source rocks.