Contrasting Deep-water Records from the Upper Permian and Lower Triassic of South Tibet and British Columbia: Evidence for a Diachronous Mass Extinction
Contrasting Deep-water Records from the Upper Permian and Lower Triassic of South Tibet and British Columbia: Evidence for a Diachronous Mass Extinction
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DOI：
10.1669/0883-1351(2003)18
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发表时间：
2003-04
期刊：
影响因子：
--
通讯作者：
P. Wignall;R. Newton
中科院分区：
文献类型：
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作者：
P. Wignall;R. Newton
摘要晚二叠世-早三叠世的海洋记录在盘古大陆西部深水边缘（不列颠哥伦比亚省的乌苏拉河）和新特提斯洋南缘高古纬度地区（藏南的色龙）的剖面中有着显著的不同。Ursula Creek剖面揭示了长兴阶海底氧值的逐步下降（生物扰动作用、自生铀富集、黄铁矿framboid种群的出现），随后在最新长兴阶和整个早三叠世持续发展富氧条件;这一事件与硅质海绵动物群的消失和多样放射虫种群的消失相吻合。色龙剖面位于远被动边缘，记录了长兴中期的海退和侵蚀，随后是长兴晚期开始的加深阶段。边界的间隔与赤道类群（有孔虫，腕足动物和海绵）的出现，表明没有灭绝的海洋沃茨在南部古纬度的变暖，由于显着的多样性增加。只有在格里斯巴赫阶晚期，各种各样的二叠纪残留物才被消除，再次显示出缺氧的证据（薄层状、自生的富含铀、富含黄铁矿的石灰岩）。因此，二叠纪末的大规模灭绝被认为是历时的50万年或更长的时间，在Panathalassa的长兴晚期灭绝与暖水类群迁移到新特提斯岛的高南古纬度地区的多样性增加相一致。
Abstract Remarkably different Late Permian–Early Triassic marine records are seen in sections from the western deep-water margin of Pangea (Ursula Creek, British Columbia) and the high paleolatitude, southern margin of the Neotethyan Ocean (Selong, South Tibet). The Ursula Creek section reveals the progressive decline of seafloor oxygen values in the Changxingian Stage (loss of bioturbation, authigenic U enrichment, appearance of pyrite framboid populations), followed by the persistent development of euxinic conditions in the latest Changxingian and throughout the Early Triassic; an event that coincides with the disappearance of a siliceous sponge fauna and the loss of diverse radiolarian populations. The Selong section, which was located on a distal passive margin, records regression and erosion in the mid-Changxingian, followed by a phase of deepening that began in the late Changxingian. The boundary interval is associated with a marked diversity increase due to the appearance of equatorial taxa (foraminifera, brachiopods, and sponges), suggesting warming without extinction in marine waters at high southern paleolatitudes. Only in the late Griesbachian Stage are the diverse Permian holdovers eliminated, again at a level showing evidence for dysoxia (thinly-bedded, authigenic U-enriched, pyrite-rich limestone). Thus, the end-Permian mass extinction is seen to be diachronous by half a million years or more, with late Changxingian extinction in Panathalassa coinciding with diversity increase associated the migration of warm-water taxa into the high southerly paleolatitudes regions of Neotethys.