Collaborative Research: Calibrating the end-Ediacaran Extinction with U-Pb Geochronology & Chemostratigraphy at a New Precambrian-Cambrian Boundary Site in Namibia & South

合作研究：用 U-Pb 地质年代学校准埃迪卡拉末期灭绝

• 批准号: 1827669
• 负责人: Emily Smith
• 金额: $ 30.43万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1827669&HistoricalAwards=false
• 关键词: Collaborative; Research; Calibrating; end; Ediacaran

The first appearance and rapid diversification of complex, multicellular animals at the dawn of the Cambrian (~540 million years ago) is conceivably the single most significant episode in the evolution of life on Earth, as it laid out the initial blueprints for the vast majority of life forms that exist today. Understanding the driving mechanisms of the Cambrian 'explosion' have been challenging because life forms that dominated the preceding period, the Ediacaran, have a sparse fossil record. In addition, the marine sedimentary rocks that preserve the Ediacaran-Cambrian transition are now scattered across the continents, hampering an unequivocal reconstruction of life and the environment at this crucial junction of the geologic history. This study focuses on key outcrops of the Ediacaran-Cambrian marine deposits with spectacular fossils and high potential for precise isotopic dating in a previously unexplored region near the Namibia-South Africa border. The results will provide new insights into the rates of paleoenvironmental and ocean chemical change during this critical time interval. In addition to public presentations and scholarly publications, a comprehensive program of educational, training, and outreach activities are planned.This project employs an integrated program of field mapping, sedimentology, chemo- and bio-stratigraphy on newly discovered marine carbonate-rich and fossiliferous Ediacaran-Cambrian sections on either side of the Orange River in Namibia and South Africa with abundant intercalated ash beds suitable to U-Pb geochronology. It will provide a high-resolution record that will help to unravel the mode and rates of biotic and coeval environmental changes at the close of the Proterozoic. The results will be a major step forward in testing the hypothesis that there were globally synchronous environmental perturbations that were genetically associated with biotic turnover across the Ediacaran-Cambrian boundary, and will lead to a better understanding of the driving mechanisms of the Cambrian radiation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

复杂的多细胞动物在寒武纪初期（约 5.4 亿年前）首次出现并迅速多样化，可以想象是地球生命进化过程中最重要的一个事件，因为它为绝大多数生命奠定了最初的蓝图。今天存在的生命形式。了解寒武纪“爆发”的驱动机制一直具有挑战性，因为主导前一时期埃迪卡拉纪的生命形式的化石记录很少。此外，保存埃迪卡拉纪-寒武纪过渡期的海洋沉积岩现在分散在各个大陆上，阻碍了在地质历史的这个关键交汇处对生命和环境进行明确的重建。这项研究的重点是埃迪卡拉纪-寒武纪海洋沉积物的主要露头，其中有壮观的化石，并且在纳米比亚-南非边境附近先前未勘探的地区进行精确同位素测年的巨大潜力。研究结果将为了解这一关键时间间隔内古环境和海洋化学变化的速率提供新的见解。除了公开演讲和学术出版物外，还计划开展全面的教育、培训和外展活动计划。该项目对新发现的海洋富含碳酸盐和化石的区域采用了实地测绘、沉积学、化学和生物地层学综合计划。纳米比亚和南非奥兰治河两岸的埃迪卡拉系-寒武纪地段具有丰富的夹灰层，适合 U-Pb 地质年代学。它将提供高分辨率记录，有助于揭示元古代末期生物和同时代环境变化的模式和速率。这些结果将是检验这一假设的重要一步，即存在全球同步的环境扰动，这些扰动在遗传上与埃迪卡拉纪-寒武纪边界的生物周转有关，并将导致人们更好地了解寒武纪辐射的驱动机制。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Preservation of erniettomorph fossils in clay-rich siliciclastic deposits from the Ediacaran Wood Canyon Formation, Nevada

• DOI: 10.1098/rsfs.2020.0012
• 发表时间: 2020-06
• 期刊: Interface Focus
• 影响因子: 4.4
• 作者: J. G. Hall;Emily F. Smith;Nobumichi Tamura;S. Fakra;Tanja Bosak

Pushing the boundary: A calibrated Ediacaran-Cambrian stratigraphic record from the Nama Group in northwestern Republic of South Africa

• DOI: 10.1016/j.epsl.2022.117396
• 发表时间: 2022-02
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: L. Nelson;J. Ramezani;J. Almond;S. Darroch;W. Taylor;D. Brenner;Ryan Furey;Madison Turner;E. F. Smith

The trace fossil record of the Nama Group, Namibia: Exploring the terminal Ediacaran roots of the Cambrian explosion

• DOI: 10.1016/j.earscirev.2020.103435
• 发表时间: 2021-01-01
• 期刊: EARTH-SCIENCE REVIEWS
• 影响因子: 12.1
• 作者: Darroch, Simon A. F.;Cribb, Alison T.;Laflamme, Marc
• 通讯作者: Laflamme, Marc

A link between rift-related volcanism and end-Ediacaran extinction? Integrated chemostratigraphy, biostratigraphy, and U-Pb geochronology from Sonora, Mexico

• DOI: 10.1130/g47972.1
• 发表时间: 2021-02-01
• 期刊: GEOLOGY
• 影响因子: 5.8
• 作者: Hodgin, Eben B.;Nelson, Lyle L.;Smith, Emily F.
• 通讯作者: Smith, Emily F.

Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

• DOI: 10.1038/s41467-019-13882-z
• 发表时间: 2020-01
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: J. Schiffbauer;T. Selly;Sarah M. Jacquet;R. Merz;L. Nelson;Michael Strange;Yaoping Cai;E. F. Smith-E.-F.-S