湖北西部建始地区志留系秀山组顶部地层新观察

发布时间：2018-06-01 14:15

本文选题：生物地层 + 岩石地层　；参考：《地层学杂志》2017年04期

【摘要】：在湖北省建始县北部细沙坝剖面志留系最上部发现腕足动物及几丁类化石。腕足动物组合以华美瓦尔达贝(Valdaria lauta)为典型分子,属于秀山动物群第二组合带;同时根据几丁类的组合带延限,综合分析确定其时代为特列奇中期,相当于秀山组上段的中部。鉴于与典型纱帽组在岩性、时代的明显差别,鄂西地区的来凤、咸丰、鹤峰、宣恩、恩施、建始、巴东等地的这套以往称作纱帽组的地层改称为秀山组为宜。建始细沙坝与桐梓韩家店、石阡雷家屯、秀山溶溪、宣恩高罗、宜昌大中坝等五地志留系对比说明,上扬子区各地志留系兰多维列统的顶界是参差不齐的,其中秀山的相关地层顶界最高,桐梓和宜昌的最低。上述情况反映当时海域沉积受广西运动的直接影响,导致地壳上升,从而海水退尽,岩层差异剥蚀强烈,此系华夏古陆向西北方向显著扩张的结果。
[Abstract]:Brachiopods and some fossils were found in the upper part of Silurian in Xieshaba section, northern Jianshi County, Hubei Province. The brachiopod assemblage takes Valdaria lautataa as a typical molecule and belongs to the second assemblage zone of Xiushan fauna, and according to the extension limit of the assemblage zone of several species, it is determined by comprehensive analysis that its age is the middle period of Terec, which is equivalent to the middle part of the upper member of Xiushan formation. In view of the obvious difference in lithology and age between the typical Yimao formation and the typical Yimao formation, it is appropriate that the strata in the west of Hubei Province, such as Laifeng, Xianfeng, Hefeng, Xuanen, Enshi, Badong and so on, should be renamed as Xiushan formation. The comparison between Xianshixiesba and Tongzi Hanjiadian, Shipathiajiatun, Xiushan dissolving stream, Xuanen Gaoluo, Yichang Dazhong dam and other five Silurian systems shows that the top boundary of the Upper Yangzi Silurian Lando Dimension system is uneven. The top boundary of Xiushan is the highest and the lowest of Tongzi and Yichang. The above situation reflects that the sediments in the sea area were directly influenced by Guangxi movement at that time, which led to the rise of the crust, which resulted in the retreating of the sea water and the strong denudation of the difference between the strata, which was the result of the significant expansion of the Cathaysian paleocontinent to the northwest.
【作者单位】：现代古生物学和地层学国家重点实验室中国科学院南京地质古生物研究所;中国科学院大学;北京大学地球与空间科学学院;
【基金】：国家自然科学基金(No.41472006,41521061,41530103)支持
【分类号】：P534.43

【相似文献】