Conodont biostratigraphy across the Permian-Triassic boundary at the Xinmin Section, Guizhou, South China
Conodont biostratigraphy across the Permian-Triassic boundary at the Xinmin Section, Guizhou, South China
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DOI：
10.1007/s12583-014-0472-0
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发表时间：
2014-10
影响因子：
3.3
通讯作者：
Ning Zhang;Haishui Jiang;Wenli Zhong;Haohao Huang;W. Xia
中科院分区：
文献类型：
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作者：
Ning Zhang;Haishui Jiang;Wenli Zhong;Haohao Huang;W. Xia
贵州省安顺新民剖面上二叠统塔隆组以层状硅质岩为主，下三叠统罗楼组底部泥岩、泥灰岩和硅质泥岩组成的连续沉积表明，它代表了跨越二叠系-三叠系界线的深水盆地相。在系统的牙形刺生物地层学研究的基础上，共鉴定出2属9种牙形刺。它使我们能够在这一段建立五个牙形刺带，按升序分别是：Clarina Changxingens带(1-3-4-2层)，Clarina yini带(4-3-5-1-1层)，Clarina Meishan带(5-1-2-5-2层)，Hindeodus Changxingsens带(5-3-1-5-3-2层)和Hindeodus parvus带(5-3-3-5-3-4层)。根据5-3-3层首次发现的细小棘球线虫，将二叠系-三叠系界线置于5-3-3层底部。新民剖面的牙形刺分带为进一步研究该段跨越二叠系-三叠系界线的地质事件提供了精确的生物地层格架。此外，新的牙形刺资料还显示，在基三叠统发育了几个硅质层。它为早三叠世的硅质岩提供了一个例外。
A continuous sedimentation at the Xinmin Section, Anshun, Guihzou Province, with the Upper Permian Talung Formation dominated by bedded siliceous rocks, and the Lower Triassic Luolou Formation consisting mudstones and marls as well as siliceous mudstones at its basal part indicates that it represents a deeper-water basinal facies across the Permian-Triassic boundary. Based on a systematic conodont biostratigraphic work, nine conodont species belong to two genera have been identified in this study. It enable us to establish five conodont zones at this section, in ascending order, they are:Clarkina changxingensisZone (beds 1-3-4-2),Clarkina yiniZone (beds 4-3-5-1-1),Clarkina meishanensisZone (beds 5-1-2-5-2),Hindeodus changxingensisZone (beds 5-3-1-5-3-2) andHindeodusparvusZone (beds 5-3-3-5-3-4), respectively. According to the first occurrence ofHindeodus parvusin bed 5-3-3, the Permian-Triassic boundary is placed at the base of bed 5-3-3. This conodont zonation of the Xinmin Section provides precise biostratigraphic framework for further investigations on the geological events across the Permian-Triassic boundary at this section. In addition, the new conodont data also reveals that several siliceous beds occurred at the basal Triassic. It provides an exception of Early Triassic Chert Gap.