松辽盆地白垩纪地层时代划分

松辽盆地经多年来地质生产和科研活动，已经建立了一套完整的地层层序，由下往上为：沙河子组、营城组、登娄库组、泉头组、青山口组、姚家组、嫩江组、四方台组、明水组等９组２７个岩性段。白垩系的上限在明水组和依安组之间，相当于马斯特里赫特阶的顶界，同位素年龄为６６Ｍａ。白垩系的下限在沙河子组和火石岭组之间，相当于贝利亚斯阶的底界，同位素年龄为１４４Ｍａ。松辽盆地白垩系属陆相地层，三分性明显，自然划分为下、中、上三统，这种划分方案正被更多的地质工作者所接受。

STRATIGRAPHIC DIVISION OF CRETACEOUS STRATA IN SONGLIAO BASIN

The Songliao Basin is one of the large intracontinental sedimentary basins in China.After the long term geologic activities and research work in the basin,a complete stratigraphic sequence has been established,namely (from the bottom to the top):Shahezi Formation,Ying Cheng Formation,Denglouku Formation,Quantou Formation,Qingshankou Formation,Yaojia Formation,Nenjiang Formation,Sifangtai Formation and Mingshui Formation,totalling 9 formations and 27 lithological members.The upper boundary of Cretaceous is between Mingshui Formation and Yi'an Formation corresponding to the top of Maastrichtian with the isotope age of 66Ma,and the lower boundary is between Shahezi Formation and Huoshiling Formation corresponding to the bottom of Berriasian with the isotope age of 144 Ma.The Cretaceous in Songliao Basin is of continental facies and characterized by 3 part division.It is obvious that the Cretaceous in Songliao Basin is reasonably divided into 3 parts,i.e. the Upper Cretaceous,the Middle Cretaceous and the Lower Cretaceous.This division is being accepted by more and more chinese geologists.