黑龙江省嘉荫县乌拉嘎断陷中、新生代地层序列与盆地演化

Mesozoic and Cenozoic Stratigraphic Sequences and Basin Evolution in Wulaga Fault-Depression,Jiayin County,Heilongjiang Province

通过对黑龙江省嘉荫县乌拉嘎盆地内各地层单元的岩石组合、生物化石组合与时代和沉积环境的系统研究与厘定,并与孙吴—嘉荫盆地其他断陷以及松辽盆地进行对比。研究表明:乌拉嘎盆地中、新生代划分为3个构造层5个岩石地层单元,并对其空间展布与演化进行了恢复,填制区域地质图。乌拉嘎盆地表现为明显的3期不同性质的盆地叠合演化特点,其间由2个明显的不整合界面分隔,即上白垩统嘉荫群与下白垩统之间的不整合和上白垩统嘉荫群与新近系孙吴组之间的不整合,从而造就了乌拉嘎中、新生代盆地的3个不同性质盆地演化阶段:早白垩世大陆裂谷断陷盆地演化阶段、晚白垩世的大型内陆坳陷盆地演化阶段和新近纪内陆山间盆地演化阶段。

Based on discussing each unit of the lithostratigraphic rock composition,fossil assemblages and depositional environment from Mesozoic to Cenozoic in Wulaga fault-depression,Jiayin County,Heilongjiang Province,and comparison with other basins in Sunwu-Jiayin and Songliao basin,the authors divided the Mesozoic and Cenozoic strata into three tectonic layers and five lithostratigraphic units,and discussed their distribution and evolution,and made the regional geological map.The Wulaga basin shows three significantly different basin evolution stages,during which the two distinct unconformities are recognised,namely： the unconformity between upper Cretaceous and Lower Cretaceous and between the Upper Cretaceous and Neogene,thus made three different types of basin evolution stages in Wulaga from Mesozoic to Cenozoic;they are Early Cretaceous rift basin evolution stage,the Late Cretaceous large scale inland depression,and Neogene inland basin evolution stages.