Recovery of Early Danian Molluscan Faunas on Seymour Island from KT Mass Extinction Event

该奖项由极地方案办公室的南极地质和地球物理方案提供，支持研究白垩纪-第三纪(KT)大灭绝后的动物群恢复，记录在南极西摩岛的岩石中。关于白垩纪末期的大灭绝事件的争论大多集中在撞击事件的有效性和直接后果上。人们普遍认为，白垩纪末期曾发生过一次重大的撞击事件。然而，在地球生物圈长期处于压力之下的时候，究竟是唯一的原因，还是“压垮骆驼的那根稻草”，仍然有相当大的讨论。直到最近，生物圈边界事件后的恢复一直笼罩在KT辩论的阴影之下。20世纪80年代末的S和90年代初的S的一些论文讨论了KT边界事件后恢复模式的性质。这些研究的重点是靠近尤卡坦半岛撞击地点的墨西哥湾沿岸地区的恢复情况。墨西哥湾沿岸恢复模式的特点是最初是一个贫瘠的区域，随后是物种稀少的存活类群和机会性物种大量繁殖，最后是海底群落的重建和多样化。墨西哥湾沿岸的复苏已成为古新世早期全球复苏的典范。在最近一项关于从北欧、北非和巴基斯坦-印度北部恢复软体动物动物群的全球概要研究中，发现没有证据表明墨西哥湾沿岸以外的地区出现了机会主义的恢复。许多作者指出，天气、区域或全球概要对KT大灭绝后发生的事件提供了重要的洞察，但它们可能掩盖了重要的恢复过程，而这些过程可能只在对局部部分的详细研究中才明显。为了加强我们对边界事件后恢复的了解，有必要对墨西哥湾沿岸以外的边界剖面进行更详细的地层学和分类学研究。西摩岛位于南极半岛的东北端，拥有已知的最完整的暴露良好的KT边界序列之一，也是南半球唯一的中陆架边界事件记录。位于南部高纬度地区，距离希克苏鲁伯撞击现场约7000公里，西摩岛上的序列将为远离撞击事件的地区海洋生物的恢复提供重要的洞察。西摩尔岛层序具有特别重要的意义，不仅因为边界暴露的地理范围(约7公里)，而且还包含马斯特里赫特(66-7400万年前)和古近纪(2300万-6600万年前)期间事件的广泛记录(1600米地层)。这个为期两年的项目的目标是完成从洛佩兹-德贝尔托达诺和索布拉尔组的大年(6300-6600万年前)收集的软体动物的分类研究。大年动物群的描述将完成对西摩岛从马斯特里赫斯到始新世(36-5700万年前)软体动物动物群的分类描述。西摩岛动物群为研究远离撞击事件的地区的动物灭绝、存活和恢复提供了机会，并将为KT大规模灭绝后恢复的全球合成提供一个重要的数据集，以便与其他地区进行比较。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports research to study faunal recovery following the Cretaceous-Tertiary (KT) mass extinction as recorded in rocks of Seymour Island, Antarctica. Most of the debate about the mass extinction event at the end of the Cretaceous has focused on the validity and the immediate consequences of the impact event. A consensus has emerged that there was a major impact event at the end of the Cretaceous. However, there is still considerable discussion as to whether it was the sole cause or "the straw that broke the camels back" coming at time when the Earth's biosphere was under prolonged period of stress. Overshadowed in the KT debate until recently has been the post boundary-event recovery of the biosphere. A number of papers in the late 1980's and early 1990's have discussed the nature of recovery patterns following the KT boundary event. These studies have focused on the recovery along of the Gulf Coast region, which was in close proximity to the impact site on the Yucatan Peninsula. The Gulf Coast recovery pattern was characterized by an initial barren zone, followed by a species-poor assemblage of surviving taxa and opportunistic blooms of species, and eventually to a rebuilding and diversification of the benthic communities. The recovery along the Gulf Coast has become a model for global recovery during the early Paleocene. In a recent global compendium study of the recovery of molluscan faunas from northern Europe, northern Africa and Pakistan-northern India, it was found that there was no evidence of opportunistic recovery blooms outside the Gulf Coast. Various authors have noted that synoptic regional or global compendia provide important insight into events following the KT mass extinction, but they may obscure important recovery processes that may be apparent only in detailed studies of local sections. To enhance our understanding of post boundary-event recovery, there is a need for additional detailed stratigraphic and taxonomic studies of boundary sections outside of the Gulf Coast region.Seymour Island, located on the northeast tip of the Antarctic Peninsula, contains one of the most complete well-exposed KT boundary sequences known and the only mid-shelf record of boundary events in the Southern Hemisphere. Located in the high southern latitudes, about 7000 km from the Chicxulub impact site, the sequence on Seymour Island will provide important insight into the recovery of marine communities in regions remote from the impact event. The Seymour Island sequence is of particular importance, not only because of the geographic extent of the exposure of the boundary (about 7 km), but it also contains an extensive record (1600 m of strata) of events during the Maastrichtian (66-74 million years ago) and Paleogene (23-66 million years ago). The goal of this two-year project is to complete the taxonomic study of the molluscs collected from the Danian (63-66 million years ago) of the Lopez de Bertodano and Sobral formations. The description of the Danian fauna will complete the taxonomic description of the molluscan faunas from the Maastrichtian to the Eocene (36-57 million years ago) on Seymour Island. The Seymour Island fauna provides an opportunity to examine faunal extinction, survival, and recovery in a region remote from the impact event and will provide an important data set for comparison with other regions for global syntheses of post KT mass extinction recovery.