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西藏申扎地区德日昂玛-下拉剖面:冈瓦纳和特提斯晚石炭世—早二叠世地层和古生物对比的桥梁
Deri′angma-Xiala section in the Xainza area, Tibet, China:A bridge for the stratigraphic and paleontological correlation between Gondwana and Tethys during the Late Carboniferous and Early Permian
【摘要】 西藏北部申扎县永珠地区德日昂玛-下拉剖面中石炭系和二叠系地层发育完整,出露良好,化石丰富。该剖面中查果罗玛组碳酸盐岩地层(泥盆纪—早石炭世)和下拉组(中二叠世)碳酸盐岩地层之间的碎屑岩夹灰岩地层,在沉积上表现为冰海相杂砾岩,在古生物化石面貌上表现为特提斯-冈瓦纳古生物群混生。古生物群混生的现象为石炭纪—二叠纪的特提斯生物区与冈瓦纳生物区之间的地层和古生物对比建立了一座桥梁。永珠组中上部地层中同时产有牙形石和腕足类,牙形石的研究表明其时代为晚石炭世莫斯科期,而腕足类的研究则表明其为早二叠世萨克马尔期。这一矛盾预示着在(亲)冈瓦纳相地区晚石炭世晚期地层缺失的意见需要重新审视。
【Abstract】 The fossiliferous Middle Carboniferous and Permian are well developed in the Deri′angma-Xiala section in the Yunzhug area, Xainza County, northern Tibet. The strata between the carbonate rocks of the Chaguoluoma Formation (Devonian-Early Carboniferous) and carbonate rocks of the Xiala Formation (Middle Permian) consist mainly of clastic rocks with limestone, which are marked by glaciomarine deposits in terms of sedimentation and mixing of Gondwanan and Tethyan faunas in terms of fossils. The mixing of faunas establishes a bridge for the stratigraphic and paleontological correlation between the Carboniferous-Permian Gondwana and Tethys realms. Conodonts and brachiopods occur together in the middle and upper parts of the Yunzhug Formation. However, study of conodonts suggests that the middle and upper parts of the Yunzhug Formation are Late Carboniferous Moscovian in age, while study of brachiopods suggests an Early Permian Sakmarian age. This contradiction implies that the view that the upper part of the Upper Carboniferous is missing in regions of Gondwanic affinity including Tibet and western Yunnan should be reconsidered.
【Key words】 Gondwana; Tethys; Late Carboniferous; Early Permian; mixed fauna; glaciomarine deposits; Xainza; Tibet;
- 【文献出处】 地质通报 ,Geological Bulletin of China , 编辑部邮箱 ,2007年01期
- 【分类号】Q91
- 【被引频次】21
- 【下载频次】379