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

西摩岛早期丹尼期软体动物群从 KT 大规模灭绝事件中恢复

• 批准号: 9814533
• 负责人: William Zinsmeister
• 金额: $ 11万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814533&HistoricalAwards=false
• 关键词: Recovery; Early; Danian; Molluscan; Faunas

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.

该奖项由极地方案办公室南极地质和地球物理方案提供，支持研究南极西摩岛岩石中记录的第三纪大规模灭绝后动物群恢复的研究。大多数关于白垩纪末期大灭绝事件的争论都集中在撞击事件的有效性和直接后果上。人们一致认为，白垩纪末发生了一次重大的撞击事件。然而，对于这是否是唯一的原因，还是在地球生物圈长期处于压力之下的时候出现的“压垮骆驼的稻草”，仍然有相当多的讨论。直到最近，在KT辩论中，生物圈的边界事件后恢复一直被蒙上阴影。在20世纪80年代末和90年代初的一些论文讨论了KT边界事件后恢复模式的性质。这些研究的重点是墨西哥湾沿岸地区沿着的复原情况，该地区非常接近尤卡坦半岛的撞击地点。墨西哥湾沿岸的恢复模式的特点是最初的贫瘠区，其次是一个物种贫乏的组合幸存的类群和机会主义的物种开花，并最终重建和多样化的底栖生物群落。墨西哥湾沿岸沿着的恢复已成为古新世早期全球恢复的典范。最近一项关于北方欧洲、北方非洲和巴基斯坦-北方印度软体动物群恢复的全球简编研究发现，没有证据表明墨西哥湾沿岸以外出现机会性恢复性水华。许多作者指出，天气区域或全球纲要提供了重要的洞察KT大灭绝后的事件，但他们可能会掩盖重要的恢复过程，可能是显而易见的，只有在详细的研究局部部分。为了提高我们对边界事件后恢复的理解，有必要对墨西哥湾沿岸地区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，包含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。西摩岛上的层序位于南半球高纬度地区，距离希克苏鲁布撞击地点约7000公里，它将为远离撞击事件的地区海洋群落的恢复提供重要的见解。西摩岛层序特别重要，不仅因为边界暴露的地理范围（约7公里），而且它还包含了马斯特里赫特阶（6600 - 7400万年前）和古近纪（2300 - 6600万年前）期间事件的广泛记录（1600米的地层）。这个为期两年的项目的目标是完成对从洛佩斯德贝尔托达诺和索布拉尔地层的达尼阶（6300万至6600万年前）收集的软体动物的分类研究。对达尼亚动物群的描述将完成对西摩岛从马斯特里赫特阶到始新世（3600万至5700万年前）的软体动物群的分类描述。 西摩岛动物群提供了一个机会，研究动物群的灭绝，生存和恢复在一个地区远离影响事件，并将提供一个重要的数据集与其他地区的全球综合后KT大规模灭绝恢复的比较。