Neoproterozoic to Early Cambrian small shelly fossil assemblages and a revised biostratigraphic correlation of the Yangtze Platform (China)
Neoproterozoic to Early Cambrian small shelly fossil assemblages and a revised biostratigraphic correlation of the Yangtze Platform (China)
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DOI：
10.1016/j.palaeo.2007.03.046
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
M. Steiner;Guoxiang Li;Y. Qian;Maoyan Zhu;B. Erdtmann
中科院分区：
文献类型：
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作者：
M. Steiner;Guoxiang Li;Y. Qian;Maoyan Zhu;B. Erdtmann
小壳化石（SSF）在扬子地台广泛分布，对于前三叶虫期早寒武世地层的生物地层细分具有巨大潜力。根据浅水区SSF记录，梅树存阶可识别出5个生物带。生物带按升序排列为：Anabarites trisulcatus-Protohertzina anabarica 组合带； Paragloborilus subglobosus-Purella squamulosa 组合区； Watsonella crosbyi 组合带（原 Heraultipegma yunnanensis 带）；含化石量少的层间；扇形华南树-张文堂吉唐诺林组合带。此外，在筇竹仙阶之上还发现了一个 SSF 生物区：Pelagiella subangulata 分类群范围区。对以前使用的Siphogonuchites triangularis-Paragloborilus subglobosus 区和Heraultipegma yunnanensis 区进行了讨论和重新定义。筛选了约80种SSF在扬子地台的时空分布。整个扬子地台都有岩相和生物相的变化，面积达2000×900 km。在较深的水陆架环境中，第一个区域以 Protohertzina anabarica-Kaiyangites novilis 组合带为代表，而较年轻的区域在南部地区则不被识别。筇竹仙台北缘以塔里木白花-房县剑竹组合带和菱形角角花分类单元范围带为代表。陕西东南部—鄂西地区的岩性和动物区系发育与扬子地台其他地区略有不同，表明与东冈瓦纳部分地区有较强的相似性。一些类群，如 W. crosbyi、P. subangulata、R. cancellatum、Microdictyon effusum、A. trisulcatus、Protohertzina unguliformis 和 P. anabarica 几乎遍布全世界，支持扬子地台与较小的西冈瓦纳地块、西伯利亚、纽芬兰和澳大利亚之间早寒武世序列的国际关联。扬子地台的六个调查区域涵盖了从早内马基特-达尔丁阶到西伯利亚地台阿达巴阶晚期/博托曼阶早期的区间。古生物地理学分析揭示了扬子地台与塔里木地台在分类上具有很强的相似性。少数物种与印度和伊朗等其他西冈瓦纳地台碎片共享。古生物地理结果并不支持先前报道的早寒武世期间澳大利亚和西伯利亚之间的华南地块的位置。
Small shelly fossils (SSFs) occur widely on the Yangtze Platform and have great potential for biostratigraphic subdivision of pre-trilobitic Early Cambrian strata. Based on the SSF record of the shallow water realm, five biozones can be recognized for the Meishucunian Stage. In ascending order the biozones are: Anabarites trisulcatus–Protohertzina anabarica Assemblage Zone; Paragloborilus subglobosus–Purella squamulosa Assemblage Zone; Watsonella crosbyi Assemblage Zone (formerly Heraultipegma yunnanensis Zone); poorly fossiliferous interzone; Sinosachites flabelliformis–Tannuolina zhangwentangi Assemblage Zone. In addition one SSF biozone is recognized for the overlying Qiongzhusian Stage: Pelagiella subangulata Taxon-range Zone. The formerly used Siphogonuchites triangularis–Paragloborilus subglobosus Zone and Heraultipegma yunnanensis Zone are discussed and redefined. Approximately 80 species of SSFs were screened for their spatial and temporal distribution on the Yangtze Platform. Variations in lithofacies and biofacies can be recognized throughout the Yangtze Platform, extending over an area of 2000×900 km. In a deeper water shelf setting the first zone is represented by the Protohertzina anabarica–Kaiyangites novilis Assemblage Zone, while younger zones are not recognized in the southern region. At the northern platform margin the Qiongzhusian is represented by the Ninella tarimensis–Cambroclavus fangxianensis Assemblage Zone and the Rhombocorniculum cancellatum Taxon-range Zone. The southeastern Shaanxi–western Hubei region followed a slightly different lithological and faunal development than the rest of Yangtze Platform, indicating a stronger similarity with parts of East Gondwana. Some taxa such as W. crosbyi, P. subangulata, R. cancellatum, Microdictyon effusum, A. trisulcatus, Protohertzina unguliformis, and P. anabarica occur nearly worldwide and support an international correlation of Early Cambrian sequences between the Yangtze Platform and smaller West Gondwanan blocks, Siberia, Newfoundland, and Australia. The six investigated zones of the Yangtze Platform comprise an interval spanning the early Nemakit–Daldynian to the late Atdabanian/early Botoman Stage on the Siberian Platform. Palaeobiogeographic analysis revealed a strong taxic similarity between the Yangtze Platform and the Tarim Platform. A smaller number of species are shared with other West Gondwanan platform fragments such as India and Iran. Palaeobiogeographic results do not support the previously reported position of the South China Block between Australia and Siberia during the Early Cambrian.