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。
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.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1995年第4期372-381,共10页
Acta Geologica Sinica
基金
国家自然科学基金(编号 49172107号)
关键词
松辽盆地
白垩纪
同位素年龄
地层
时代划分
Songliao Basin, Cretaceous, lake transgressive sedimentary sequence,isotopic age, stratigraphic classification
