辽东半岛南部晚先寒武纪宏体生物序列

MACROFOSSIL SEQUENCE OF THE LATE PRECAMBRIAN FROM THE SOUTHERN LIAODONG PENINSULA

辽东半岛市部上先寒武系自下而上划分为4群15组,其中细河群的三个组即钓鱼台组、南芬组、桥头组产宏观藻类化石;五行山群的长岭子组、南关岭组产蠕虫和宏观藻类化石;金县群兴民村组产类水母化石,葛屯组产蠕虫、宏观藻类化石,上覆的下寒武统碱厂组产三叶虫和古杯动物化石。上先寒武系7个宏体生物化石层位构成一个连续的、完整的宏体生物序列,可分为4个演化阶段:①细河期宏观藻类发生发展阶段;②五行山期蠕虫发生发展阶段和宏观藻类发展阶段;③兴民村期类水母发生发展阶段;④葛屯期蠕虫和宏观藻类新的发展阶段。据此可以划分为4个生物群,即细河生物群(800Ma前)、五行山生物群(800—700Ma)、金县生物群(677Ma)、满家滩生物群(600Ma)。另外早寒武世三叶虫和古杯动物组成葫芦套生物群,为早寒武世晚期。辽东半岛与苏皖北部晚先寒武纪地层不仅沉积序列相同,而且宏体生物序列也基本相同,两区生物地层完全可以对比。辽东半岛南部晚先寒武纪宏体生物序列的建立及其在同一地层区的延展性,提高了本区晚先寒武纪地层剖面的地位。使其可能成为全球晚先寒武纪生物地层层型剖面。

The late Precambrian strata are divided into 4 groups and 15 formations in the southern Liaodong peninsula, in which the Xihe Group includes 3 formations, namely, Diaoyutai, Nanfen and Qiaotou Formations yielding macroscopic algae; Wuhangshan Group includes Changlingzi and Nanguanling Formations yielding worm and macroscopic algae; Xinmincun Formation of Jinxian Group yields medusoid fossils and Getun Formation yields worm. and macroscopic algae. The overlying Jianchang Formation of the Lower Cambrian yields trilobite and archaeccyatha fossils. There are 7 macrofossil beds in the late Procambrian strata, which form a successive and complete macrofossil sequence. This sequence is divided into 4 evolution stages: 1. Macroscopic algae occuring and developing stage in Xihe Age; 2. Worm occuring and developing, and macroscopic algae developing stage in Wuhangshan Age; 3. Medusoid occuring and developing stage in Xinmincun Age; 4. Worm and macroscopic algae developed new stage in Getun Age. On the base of this 4 stages, the macrofossils are divided into 4 biota, namely, Xihe biota (800Ma before), Wuhangshan biota (800-700Ma), Jinxian biota (677Ma) and Manjiatan biota (600Ma). In addition, trilobite and archaeocyatha fossils from the lower Cambrian constitute Hulutao biota. It belongs to the late stage of the late Cambrian. In the southern Liaodong peninsula, northern Jiangshu anal Anhui, there are the same sedimentary sequence and macrofossil sequence. So, the biota beds in these area can be contrasted each other. The macrofossil sequence established and its extensibilhy in the same bed make the strata section of the upper Precambrian in the southern Liacdong peninsula more completly and problely become biostratigraphy stratotype section for global upper Precambrian.