松辽盆地白垩纪青山口组地质时代探讨

摘要

The Cretaceous Qingshankou Formation in Songliao Basin has abundant Songhuajiang biome fossils,study of biostratigraphy indicated that the age of Qingshankou Formation should be the Late Cretaceous.Dark mudstones and shales of the Qingshankou Formation were of high organic carbon and low diasteranes contents.Organic geochemical characteristics were illustrated by biomarkers and gammacerane , and positive excursion of kerogen isotopes.It was suggested that the dark mudstones and shales in Qingshankou Formation were products of lacustrine anoxic records in the extreme greenhouse climate period.Angiosperm farina at the bottom of Qingshankou Formation such as Cranwellia, Lythraites, Complexiopollis, Borealipollis, Buttinia, Areicipites, Sabalpollenites etc.has significant era significance , and ages of eruption zircon U-Pb has also proved that the age of the bottom of Qingshankou Formation in Songliao Basin should be Turonian and be not Cenomanian.%松辽盆地白垩纪青山口组赋存有丰富的松花江生物群化石,生物地层学研究表明其时代属晚白垩世.青山口组黑色泥岩、页岩具有有机碳含量高,干酪根碳同位素正偏、重排甾烷含量低、普遍存在伽玛蜡烷生物标志化合物,代表了温室气候时间窗内古湖泊贫氧-缺氧环境条件下的沉积产物.而青山口组底部出现的Cranwellia, Lythraites, Complexiopollis, Borealipollis, Buttinia, Areicipites, Sabalpollenites等一些具重要时代意义的被子植物花粉,以及锆石U-Pb年龄也证实了青山口组底界已属Turonian期,而非Cenomanian期.