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二叠纪—三叠纪之交发生了显生宙最大的生物灭绝事件,同时发生了复杂的环境变化.由于陆相二叠系-三叠系界线附近生物化石记录没有海相记录完整,同时也缺乏其他可靠的年代地层标志,所以如何标定陆相剖面的二叠纪—三叠纪界线一直是研究热点和难点.贵州威宁金钟地区二叠纪—三叠纪之交位于康滇古陆的东侧,毗邻海陆过渡相区,可以与同期的浅海碎屑岩相、海陆过渡相、陆相剖面进行由海到陆“追索式”的生物地层对比,是我国研究海、陆相二叠系-三叠系界线及对比的关键研究区之一.研究区的金钟二叠系-三叠系界线剖面中化石丰富,共发现双壳类化石4属6种,叶肢介2属4种,植物化石9属及腕足类化石1属,为海、陆相地层对比提供了桥梁.依据叶肢介Euestheria gutta-Palaeolimnadia xuanweiensis组合、植物Annalepis-Peltaspermum组合以及双壳类Pteria ussurica variabilis-Neoschizodus orbicularis组合的生物化石时代归属讨论,识别出金钟剖面的二叠系-三叠系界线应该在卡以头组下部.通过与邻区不同相剖面的对比,提出双壳类Pteria ussurica variabilis-Neoschizodus orbicularis组合以及陆相的叶肢介Euestheria gutta-Palaeolimnadia xuanweiensis组合可以作为三叠纪最早期的识别和对比标志.
At the turn of the Permian-Triassic period, the largest biocide occurred in the Phanerozoic and complicated environmental changes occurred at the same time. Because no marine records were recorded near the Permian-Triassic boundary, So it is always a hot and difficult issue how to calibrate the Permian-Triassic boundary line in the continental facies.At the end of the Permian-Triassic period in the Weining area of Weining, Guizhou, The eastern side of the land, adjacent to the transition zone of land and sea, can be compared with the biological stratigraphy from sea to land and “recourse” in the same period with the shallow marine clastic lithofacies, land-sea transitional facies and continental facies. Terrigenous Permian-Triassic boundary and one of the key areas for comparison.The fossils are abundant in the Permian-Triassic boundary section of the study area, and 6 species of 4 genera of bivalve fossils were found, 4 genera of 2 genera, 9 genera of fossil plants and 1 genus of brachiopods, which provide a bridge for the comparison of marine and terrestrial strata.Based on the combination of Euestheria gutta-Palaeolimnadia xuanweiensis, the plant Annalepis-Peltaspermum combination and the bivalve Pteria ussurica variabilis-Neoschizod us orbicularis assemblage, we found that the Permian-Triassic boundary of the Admiralty profile should be in the lower part of the Qa’idou head.According to the comparison of the different phase profiles with the adjacent zone, we proposed that the bivalve Pteria ussurica variabilis- The combination of Neoschizodus orbicularis and terrestrial Euestheria gutta-Palaeolimnadia xuanweiensis could be the earliest identification and contrast marker in the Triassic.