【摘要】 用超声波分散—沉降分离—K—Ar稀释法直接测定同沉积泥质组分的同位素年龄;青山口组暗色泥岩的视沉积年龄为1119.9—89.0Ma;嫩江组上部暗色泥岩的视沉积年龄为77.6—76.8Ma;泉头组泥岩的视沉积年龄为123Ma.用Rb—Sr等时线法测得嫩江组下部泥质灰岩—泥岩层系的视沉积年龄为81Ma;泉头组中部泥质蒸发盐岩的视沉积年龄为122.2Ma。据此草拟出松辽盆地白垩纪地层时代划分的修正方案。更多还原

【Abstract】 Situated in the northeast part of China (latitudes 42 ° -49 ° N; longitudes 120 ° -128 ° E), the Songliao Basin is a Cretaceous nearshore continental basin. The authors of this paper determined, for the first time, the isotopic ages of the Cretaceous Quantou Formation to Nenjiang Formation (K1q-K2n) of the basin with K-Ar and Rb-Sr methods using samples of mudstones, carbonate rocks and evaporites. The K-Ar ages of mudstones are 123.3 ± 8.3Ma for the third member of the Quantou formation (K1q3) , 111.9-89.0Ma for the Qingshankou Formation (K2qn)and 77.6-76.8 Ma for the fourth member of the Nenjiang Formation (K2n4). The Rb-Sr isochrone age of carbonate rocks of the first and second members of the Nenjiang Formation (K2n1+2) is 81 Ma and that of evaporites of the third member of the Quantou formation (K1q3)is 122.2Ma.Based on the above isotopic age data, the authors propose a modified stratigraphic classification scheme for the Mesozoic and Cenozoic sequences of the Songliao Basin. The detailed procedures of sampling, mineral separation and age determination are also presented.更多还原