论文部分内容阅读
贵州桐梓红花园山王庙的奥陶系-志留系分界地层出露好、有笔石带控制且发育介壳相化石,一直被认为是华南最佳剖面之一。本文对该剖面重新剖析,结合桐梓县境南区另外几条剖面的资料分析,提出如下新认识:山王庙剖面的“赫南特贝层”(HirnantiaBed:AFA295-305)和“介壳层”(Shelly Bed:AFA306-311c)宜合并统称为观音桥层,皆归于奥陶系;对照宜昌王家湾,将观音桥层与Normalograptus extraordinarius带上部和N.persculptus带下部对比;确定观音桥层与龙马溪组之间缺失N.persculptus带上部、A.ascensus带和P.acuminatus带大部分的地层。典型赫南特贝动物群延至A.ascensus带甚至更高层位的观点应予以修正。靠近黔中古陆北缘的诸多地点,观音桥层的厚度虽有变化,均宜视为同期沉积,唯上覆地层时代不同。赫南特贝动物群是在特定时期、特定环境中生存的特定底栖生物群落,是奥陶纪末大灭绝首幕后的产物,指示了寒凉、海退、相对浅水、底域富氧的环境条件,有重要的时代、环境和古地理意义。
The Ordovician-Silurian boundary strata of Shanwangmiao, Tongzi Red Garden, Guizhou, are well exposed and have lithofacies control and development of crust-phase fossils. They have been considered as one of the best profiles in South China. Based on the reanalysis of the profile and the analysis of the data from several other profiles in the southern area of Tongzi County, the following new understanding is proposed: The “HirunantiaBed: AFA295-305” and the " (Shelly Bed: AFA306-311c) should be collectively referred to as the Guanyin Bridge layer, all belong to the Ordovician; control Yichang Wangjiawan, the Guanyin Bridge layer with Normalograptus extraordinarius belt and N.persculptus with the lower part of the contrast; to determine Guanyin Bridge N.persculptus zone, A.ascensus zone and P.acuminatus zone are mostly missing between the layer and Longmaxi Formation. The view that typical Hernn Teal fauna extends to A. ascensus with even higher strata should be amended. Close to the northern edge of the ancient land of Guizhou in many places, although the thickness of the Guanyin Bridge changes, should be regarded as contemporaneous deposition, only overlying strata different times. The Hernantubere fauna is a specific benthic community that survives in a given period of time and in a specific environment and is the product of the first backstage of the Ordovician massacre of late Ordovician, indicating cold, receding, relatively shallow, basal oxygen-rich Environmental conditions, there are important times, environment and paleogeographic significance.