The Late Permian crisis: the continental record from Russia.

二叠纪晚期危机：来自俄罗斯的大陆记录。

基本信息

批准号：
NE/C518973/1
负责人：
Michael Benton
金额：
$ 25.49万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FC518973%2F1
关键词：
Late Permian crisis continental record

项目摘要

The end-Permian crisis marks the largest known mass extinction of life. About 50% of families of plants and animals died out in the sea, which scales to a loss of some 80-96% of species. The crisis was probably just as bad for organisms on land, but they have not been worked out yet. The event seems to have been just as serious at the local scale: close study of the rock succession in China shows that more than 90% of species died out. But how long did the event last? Was it a single, overnight hit, or did it take thousands, or even millions, of years? Opinions have changed: ten years ago, it was supposed to have lasted for 10 million years (Myr), but new dating methods show it lasted perhaps 0.5 Myr or less. These dates are still debated. Was it one event or two? What was once seen as a single long drawn-out extinction phase through the Late Permian is now seen as two events, one at the Capitanian-Wuchiapingian boundary (the CW event), some 260 Myr ago, and the end-Permian event, just below the Permo-Triassic boundary (PTB), 251 Myr ago. What caused this huge catastrophe? Many ideas have been suggested, but there are now two main hypotheses, Siberian volcanism and impact. Evidence for impact has been received enthusiastically by some, but the detail in both reports has been heavily criticised. The most widely accepted model for the PTB extinction is a chain of events following repeated eruptions of the Siberian Trap basalts over perhaps 0.5 Myr. The eruptions pumped a variety of gases into the atmosphere that led to severe acid rain. The acid rain killed land plants, and soil was stripped, destroying habitats on land. The rise in carbon dioxide and global warming was made worse by the dramatic release of methane from frozen reserves in the deep sea, which combined to give a runaway greenhouse effect, where temperatures just kept rising. Global warming also led to low oxygen conditions in the seas. This then killed 90% or more of life in the sea and on land. A similar pattern has been suggested for the earlier CW event, perhaps linked to the Emeishan volcanics in China. Recovery from the mass extinction took time. Worldwide, species numbers remained low through the Early Triassic, a time of perhaps 6 Myr. The recovery period was longer than that though, as indicated by various 'gaps' - disappearances of major life modes, such as coral reefs and forests (the 'coal gap') through the Early and Mid Triassic, a time span of 15-20 Myr. Ecosystems on land in the Russian successions had not achieved their pre-extinction diversities by the end of the Mid Triassic, and it was only some 25-30 Myr after the PTB event that communities apparently recovered their pre-extinction diversity and complexity. It's important to understand the PTB crisis since many features of the climate crisis model are being repeated today: release of gases and acid rain, global warming over hundreds of years, stagnant waters, and steady loss of species. Looking to the past may be a useful way to predict what may happen in the future. We have access to fantastic rock sections in Russia that cross the CW and PTB boundaries in dozens of places. With our team of British and Russian scientists, we want to tackle a whole string of questions: How do timings and patterns of extinction on land match those in the sea? Can the CW and P18 events be distinguished on land? What were the environmental changes, as read from the rocks? What evidence is there for and against the proposed massive plant killing and soil wash-off at the beginning of the Triassic? How did life on land respond to the two crises? What was the pattern of ecosystem collapse? Is there evidence for ecological or taxonomic selectivity? What were the global rates for loss of life on land, and how do these compare with the scale of the marine crisis? What was the nature of the recovery through the Early and Middle Triassic, in terms of rebuilding total diversity and ecosystems?

二叠纪末危机标志着已知最大规模的生命灭绝。大约 50% 的动植物科在海洋中灭绝，从而导致大约 80-96% 的物种消失。这场危机对于陆地上的生物来说可能同样糟糕，但问题尚未得到解决。这一事件在当地范围内似乎同样严重：对中国岩石演替的仔细研究表明，超过 90% 的物种灭绝了。但该事件持续了多长时间？它是一夜之间的轰动，还是花了数千年、甚至数百万年的时间？人们的看法发生了变化：十年前，它应该持续了 1000 万年（Myr），但新的测年方法显示它可能持续了 0.5 Myr 或更短。这些日期仍在争论中。这是一两个事件吗？曾经被视为贯穿二叠世晚期的单一漫长灭绝阶段现在被视为两个事件，一个发生在卡皮坦阶-乌恰平阶边界（CW 事件），大约 260 密尔前，另一个是二叠纪末事件，仅发生在二叠纪末期。位于二叠纪-三叠纪边界 (PTB) 下方，距今 251 Myr。是什么原因造成了这场巨大的灾难呢？人们提出了许多想法，但现在有两个主要假设：西伯利亚火山活动和撞击。一些人热情地接受了影响的证据，但两份报告中的细节都受到了严厉批评。最广泛接受的 PTB 灭绝模型是西伯利亚陷阱玄武岩在大约 0.5 密尔范围内反复喷发后发生的一系列事件。火山喷发将多种气体排放到大气中，导致严重的酸雨。酸雨杀死了陆地植物，土壤被剥离，破坏了陆地上的栖息地。深海冰冻储量中甲烷的大量释放加剧了二氧化碳的上升和全球变暖，这两者结合起来造成了失控的温室效应，导致气温不断上升。全球变暖还导致海洋中的低氧条件。这导致海洋和陆地上 90% 或更多的生物死亡。早期的 CW 事件也有类似的模式，可能与中国的峨眉山火山有关。从大规模灭绝中恢复需要时间。在整个三叠纪早期，世界范围内的物种数量仍然很低，大约为 6 密尔。然而，恢复期比这要长，正如各种“间隙”所表明的那样——主要生命模式的消失，如珊瑚礁和森林（“煤炭间隙”）到三叠纪早期和中期，时间跨度为 15-20 年。密尔。到三叠纪中期末期，俄罗斯群落中的陆地生态系统尚未达到灭绝前的多样性，而在 PTB 事件发生后仅约 25-30 密尔，群落就明显恢复了灭绝前的多样性和复杂性。了解 PTB 危机很重要，因为气候危机模型的许多特征今天正在重复：气体和酸雨的释放、数百年来的全球变暖、停滞的水域和物种的持续丧失。回顾过去可能是预测未来可能发生的事情的有用方法。我们可以在俄罗斯的数十个地方看到跨越 CW 和 PTB 边界的奇妙岩石部分。我们希望与英国和俄罗斯科学家组成的团队一起解决一系列问题：陆地上的灭绝时间和模式与海洋中的灭绝时间和模式如何匹配？ CW和P18事件在陆地上能区分吗？从岩石上可以看出，环境发生了哪些变化？有哪些证据支持和反对三叠纪初期大规模植物杀戮和土壤冲刷的提议？陆地生命如何应对这两次危机？生态系统崩溃的模式是什么？是否有生态或分类学选择性的证据？全球陆地生命损失率是多少？与海洋危机的规模相比如何？就重建总体多样性和生态系统而言，早三叠世和中三叠世的恢复本质是什么？