Collaborative Research: Permian-Triassic Mass Extinction in Antarctica

该奖项由极地项目办公室的南极地质和地球物理项目提供，支持对南极洲河流沉积物的跨学科研究，以寻找二叠纪-三叠纪边界生物史上最大规模灭绝的原因。直到最近，这个边界一直难以定位，并且被认为在南极洲是明确不整合的。新的研究，特别是碳同位素化学地层学、古土壤和根迹作为古生态系统指标的研究，以及化石植物、爬行动物和花粉生物地层学的改进，现在表明可以确定边界的精确位置，并导致局部发现铱异常、震荡石英和含外星惰性气体的富勒烯。这些异常与一种独特的粘土角砾岩层有关，与南非和澳大利亚已知的地层相似，并被视为森林砍伐的证据。已经有来自南极洲和其他地方的大量证据表明，陆地上的大规模灭绝是突然的，与海洋的灭绝是同步的。现在的问题是，是什么导致了这样的死亡和破坏。这些和其他二叠纪-三叠纪边界剖面的碳同位素值非常低，很可能是甲烷包合物发生灾难性不稳定的原因。要从可能的储层中获得模型中所模拟的甲烷量，需要发生诸如火山撞击、洪水-玄武岩喷发或大陆架崩塌等灾难性事件，这些事件都独立地与大灭绝有关，并且有独立的证据。要想拆散这些不同的假设，就需要仔细地重新检查似乎代表二叠纪-三叠纪边界的地层，并寻找更有信息的序列，就像白垩纪-第三纪边界的情况一样。这项关于边界层和古土壤的地球化学和岩石学的合作研究（由Retallack负责），关于边界层间的碳同位素变化（由Jahren负责），以及关于富勒烯、铱和氦（由Becker负责）的合作研究，旨在测试这些关于南极洲二叠纪-三叠纪边界的想法，并阐明导致地球上最大规模物种灭绝的过程。这项研究的实地工作将在横贯南极山脉中部和维多利亚地南部进行，初步目标是检查跨界连续性的地层序列。地层连续性是工作成功的关键因素。如果现场工作表明足够连续的部分，完整的分析程序将遵循现场工作。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports an interdisciplinary study of fluvial sediments in Antarctica for evidence of what caused the greatest of all mass extinctions in the history of life at the Permian-Triassic boundary. This boundary was, until recently, difficult to locate and thought to be unequivocally disconformable in Antarctica. New studies, particularly of carbon isotopic chemostratigraphy and of paleosols and root traces as paleoecosystem indicators, together with improved fossil plant, reptile and pollen biostratigraphy, now suggest that the precise location of the boundary might be identified and have led to local discovery of iridium anomalies, shocked quartz, and fullerenes with extraterrestrial noble gases. These anomalies are associated with a distinctive claystone breccia bed, similar to strata known in South Africa and Australia, and taken as evidence of deforestation. There is already much evidence from Antarctica and elsewhere that the mass extinction on land was abrupt and synchronous with extinction in the ocean. The problem now is what led to such death and destruction. Carbon isotopic values are so low in these and other Permian-Triassic boundary sections that there was likely to have been some role for catastrophic destabilization of methane clathrates. Getting the modeled amount of methane out of likely reservoirs would require such catastrophic events as bolide impact, flood-basalt eruption or continental-shelf collapse, which have all independently been implicated in the mass extinction and for which there is independent evidence. Teasing apart these various hypotheses requires careful re-examination of beds that appear to represent the Permian-Triassic boundary, and search for more informative sequences, as was the case for the Cretaceous-Tertiary boundary. This collaborative research on geochemistry and petrography of boundary beds and paleosols (by Retallack), on carbon isotopic variation through the boundary interval (by Jahren), and on fullerenes, iridium and helium (by Becker) is designed to test these ideas about the Permian-Triassic boundary in Antarctica and to shed light on processes which contributed to this largest of mass extinctions on Earth. Fieldwork for this research will be conducted in the central Transantarctic Mountains and in Southern Victoria Land with an initial objective of examining the stratigraphic sequences for continuity across the boundary. Stratigraphic continuity is a critical element that must exist for the work to be successful. If fieldwork indicates sufficiently continuous sections, the full analytical program will follow fieldwork.