The Late Permian crisis: the continental record from Russia.

二叠纪末期的危机标志着已知的最大规模的生命大灭绝。大约50%的动植物在海洋中灭绝，这导致大约80%-96%的物种消失。这场危机对陆地上的生物来说可能同样糟糕，但它们还没有得到解决。这一事件在当地似乎也同样严重：对中国岩石演替的仔细研究表明，超过90%的物种灭绝了。但这场活动持续了多长时间？它是一夜成名，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。这些日期仍有争议。是一个项目还是两个项目？曾经被认为是贯穿晚二叠世的一个漫长的灭绝阶段，现在被视为两个事件，一个发生在大约260迈尔前的首都-乌恰平纪界线(CW事件)，另一个是二叠纪末期事件，恰好在二叠纪-三叠纪界线(PTB)之下，251迈尔之前。是什么导致了这场巨大的灾难？有很多观点被提出，但现在有两个主要的假说，西伯利亚火山作用和影响。一些人热情地收到了影响的证据，但这两份报告中的细节都受到了严厉批评。最被广泛接受的PTB灭绝模型是西伯利亚圈闭玄武岩在大约0.5Myr期间反复喷发后发生的一系列事件。火山喷发将各种气体排放到大气中，导致了严重的酸雨。酸雨杀死了陆地上的植物，土壤被剥离，摧毁了陆地上的栖息地。二氧化碳和全球变暖的加剧，是因为深海冻结储备的甲烷急剧释放，这些因素加在一起造成了失控的温室效应，那里的气温一直在上升。全球变暖也导致了海洋中的低氧条件。然后，这杀死了90%或更多的海洋和陆地上的生命。早些时候的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过来需要时间。在世界范围内，物种数量在早三叠世保持在较低水平，当时可能只有6英里。然而，恢复期要长于此，正如从早、中三叠世珊瑚礁和森林等主要生命模式的消失所表明的那样，时间跨度为15-20 Myr。到中三叠世结束时，俄罗斯演替中陆地上的生态系统尚未达到灭绝前的多样性，直到PTB事件发生后约25-30Myr，群落才明显恢复到灭绝前的多样性和复杂性。理解肺结核危机很重要，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、死水和物种的稳定丧失。回顾过去可能是预测未来可能发生的事情的一种有用方式。我们可以在俄罗斯的几十个地方接触到跨越CW和PTB边界的奇妙的摇滚部分。与我们的英国和俄罗斯科学家团队一起，我们希望解决一系列问题：陆地物种灭绝的时间和模式与海洋物种灭绝的时间和模式是如何匹配的？在陆地上能区分CW和P18事件吗？从岩石上读到的环境变化是什么？有什么证据支持和反对在三叠纪开始时提出的大规模植物杀戮和土壤冲刷？陆地上的生活是如何应对这两场危机的？生态系统崩溃的模式是什么？是否存在生态或分类选择性的证据？全球陆地生命损失率是多少，与海洋危机的规模相比又如何？在重建完全多样性和生态系统方面，早、中三叠世恢复的性质是什么？

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?