下扬子中生代沉积盆地演化

Evolution of Mesozoic Sedimentary Basins in the Lower Yangtze

通过对下扬子地区各地层分区中生代岩石地层序列、沉积建造详细分析以及生物地层与年代地层划分对比,在盆地原型恢复、盆地充填序列和岩相古地理综合分析的基础上,划分出下扬子陆块中生代不同时段的5类沉积盆地:陆表海(T1-2)、周缘前陆盆地(T3-J1)、压陷盆地(T3-J2)、断陷盆地(J3-K)和拉分盆地(J3-K),初步建立了下扬子陆块中生代沉积盆地时空分布格架.分析了下扬子中生代盆地沉积大地构造环境演化历程:三叠纪-早侏罗世为与特提斯海演化相关的构造阶段,分为早三叠世-中三叠世陆表海和晚三叠世-早侏罗世前陆盆地2个亚阶段;中侏罗世-白垩纪转化为滨太平洋构造阶段,中侏罗世以挤压构造背景为主,大部分地区为隆升剥蚀区,晚侏罗世-白垩纪为强裂伸展拉张期,发育了一系列北东向火山-沉积断陷盆地和拉分盆地,盆-岭构造格局形成.

The Lower Yangtze continent formed during Mesozoic is divided into 5 types of sedimentary basin with different time frames,namely,epeiric sea （T1-2 ）,peripheral foreland basin（T3-J 1 ）,pressurized basin（T3-J 2 ）,fault-depression basin（J 3-K）, and pull apart basin （J 3-K）in this paper based on the study of lithostratigraphy,sedimentary formation,biostratigraphic and chronostratigraphic correlation,prototype basin,basin filling sequences,and comprehensive lithofacies paleogeographic analy-sis of the study area in addition.The space distribution framework of Mesozoic Lower Yangtze continental sedimentary basin is established,and the tectonic environment evolution is discussed.It is found that the Triassic-Early Jurassic tectonic phase is re-lated to the evolution of Tethys Sea,which can be divided into two sub-phases of Early-Middle Triassic epeiric sea and Late Triassic foreland basin.The Jurassic-Cretaceous phase transformed to Peri-Pacific tectonic domain can be divided into two sub-phases.Early-Middle Jurassic dominated by compressive tectonic background mainly developed the uplift and erosion areas, whereas Late Jurassic-Cretaceous characterized by an extensional tectonic environment developed a series of NE volcanic-sedi-mentary fault-depression basin and pull apart basin,which in turn formed basin-range tectonic framework.