Determining the geographical extent and radiometric age of the Paleocene-Eocene boundary ejecta strewn field

确定古新世-始新世边界喷射物散布场的地理范围和辐射年龄

• 批准号: 1737100
• 负责人: Morgan Schaller
• 金额: $ 35万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1737100&HistoricalAwards=false
• 关键词: Determining; geographical; extent; radiometric; age

Extraterrestrial impacts have played a substantial role in shaping the evolution of life on this planet. In 2016, evidence was discovered of an impact event that coincided with a major climatic event 56 million years ago at the Paleocene-Eocene (P-E) boundary. Evidence includes characteristic glass spherules and shocked mineral grains (known as ejecta) that were thrown from the impact site. The first solid evidence of an extraterrestrial impact at the P-E boundary raises many questions about the potential location of the source crater, the extent of the strewn field and exact age of the material. This project will determine the global geographic extent and the absolute age of the ejecta through an extensive search of sediments at known localities where the P-E boundary is complete and by radiometrically dating the material. The P-E climate event is marked by a rapid increase in atmospheric carbon accompanied by 5-8 degrees C global warming. It is important to understand the conditions surrounding this event because it is the best geologic analog to our current anthropogenic carbon release and climate change, and regardless of the triggering mechanism, gives us a roadmap for what to expect in the future. This time period also marks the origination of the primate lineage that ultimately resulted in the evolution of humans. Understanding the circumstances of the impact event at the P-E boundary will significantly advance our scientific understanding of the evolution of life and climate over the past 56 million years. Broader impacts of the project include the support of a postdoctoral scholar, several undergraduate students and two principal investigators, one of whom is early career. High school science teachers will also engage in the study during the summer.This research builds on recent findings of extraterrestrial impact ejecta at the P-E boundary in the Atlantic coastal plain and in sediments from the Blake Nose section offshore Florida. Ejecta material was found within the onset of the negative Carbon Isotope Excursion (CIE) that marks the P-E boundary globally. This study's research approach is similar to the search for the Cretaceous-Paleogene (K-Pg) boundary impact crater that eventually led to the discovery of the Chicxulub impact site. The project aims to provide the first radiometrically dated and potentially global fiducial marker for the P-E boundary. Anticipated results include: 1) strewn field map and location of P-E impact region; 2) radiometric age of P-E boundary using 40Ar/39Ar methods; 3) establishment of P-E ejecta as a precise temporal horizon and correlation tool; and 4) framework for future research (a) to address any causal linkages between the P-E impact and the P-E climate perturbation and (b) to assess the precise timing of the P-E biotic and climatic changes and the globally observed CIE. The climatic and biotic changes that occur at the P-E boundary are substantial; for instance, the primate lineage that eventually led to humans arose at this boundary, and deep ocean changes resulted in mass extinction in benthic marine microfauna. Hence, if an extraterrestrial impact played a role in this chapter of Earth History, the record and circumstances of such an event are crucial observations.

地外撞击在塑造这个星球上的生命进化方面发挥了重要作用。2016年，在古新世-始新世（P-E）边界发现了一次撞击事件的证据，该事件与5600万年前的一次重大气候事件相吻合。证据包括从撞击现场抛出的特征性玻璃小球和冲击矿物颗粒（称为喷出物）。在P-E边界的外星撞击的第一个确凿证据提出了许多关于源陨石坑的潜在位置，散布场的范围和材料的确切年龄的问题。该项目将通过广泛搜索P-E边界完整的已知地点的沉积物并通过放射性测定物质的年代来确定喷出物的全球地理范围和绝对年龄。 P-E气候事件的特点是大气碳迅速增加，伴随着5 - 8摄氏度的全球变暖。重要的是要了解围绕这一事件的条件，因为它是我们目前人为碳排放和气候变化的最佳地质模拟，无论触发机制如何，都为我们提供了未来预期的路线图。这一时期也标志着灵长类血统的起源，最终导致了人类的进化。了解P-E边界的撞击事件的情况将大大推进我们对过去5600万年来生命和气候演变的科学理解。该项目更广泛的影响包括一名博士后学者，几名本科生和两名主要研究人员的支持，其中一人是早期职业生涯。高中科学教师也将在夏季参与这项研究。这项研究建立在最近在大西洋沿海平原P-E边界和佛罗里达近海布莱克鼻段沉积物中发现的外星撞击喷出物的基础上。喷出物材料被发现在负碳同位素漂移（CIE）的开始，标志着全球P-E边界。这项研究的研究方法类似于最终导致发现希克苏鲁布撞击地点的寻找白垩纪-古近纪边界撞击坑。该项目旨在为P-E边界提供第一个辐射测年的、可能是全球性的基准标记。预期成果包括：结果表明：（1）P-E喷溢物分布图和P-E碰撞区位置，（2）P-E边界的~（40）Ar/~（39）Ar法测定年龄，（3）P-E喷溢物作为精确时间层位和对比工具的建立，（4）P-E喷溢物的同位素年龄和同位素年龄的测定，（5）P-E喷溢物的同位素年龄和同位素年龄的测定，（6）P-E喷溢物的同位素年龄和同位素年龄的测定，（7）P-E喷溢物的同位素年龄和同位素年龄的测定，（8）P-E喷溢物的同位素年龄和同位素年龄的测定，（9）P-E喷溢物的同位素年龄和同位素年龄的测定，（10）P-E喷溢物的同位素年龄和同位素年龄的测定，（10）P-E喷溢物的同位素年龄和同位素年龄的测定，（10）P-E喷溢物的同位素年龄和同位素年龄的测定，（10）P-E喷溢物的同位素年龄和同位素年龄的测定和4）未来研究的框架（a）解决P-E影响和P-E气候扰动之间的任何因果联系，（B）评估P-E气候扰动的精确时间。生物和气候变化以及全球观测到的CIE。在P-E边界发生的气候和生物变化是巨大的;例如，最终导致人类出现的灵长类谱系在这一边界出现，深海变化导致海底海洋微型动物群的大规模灭绝。因此，如果外星人的影响在地球历史的这一章中发挥了作用，那么这种事件的记录和环境是至关重要的观察。

项目成果

Widespread and intense wildfires at the Paleocene-Eocene boundary

古新世-始新世边界广泛而强烈的野火

• DOI: 10.7185/geochemlet.1906
• 发表时间: 2019
• 期刊: Geochemical Perspectives Letters
• 影响因子: 4.9
• 作者: Fung, M.K.;Schaller, M.F.;Hoff, C.M.;Katz, M.E.;Wright, J.D.
• 通讯作者: Wright, J.D.

Initial 40 Ar‐ 39 Ar Ages of the Paleocene‐Eocene Boundary Impact Spherules

古新世—始新世边界撞击球体的初始 40 Ar — 39 Ar 年龄

• DOI: 10.1029/2019gl082473
• 发表时间: 2019
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Schaller, Morgan F.;Turrin, Brent D.;Fung, Megan K.;Katz, Miriam E.;Swisher, Carl C.
• 通讯作者: Swisher, Carl C.

The extraterrestrial impact evidence at the Palaeocene–Eocene boundary and sequence of environmental change on the continental shelf

古新世—始新世边界的地外撞击证据及大陆架环境变化序列

• DOI: 10.1098/rsta.2017.0081
• 发表时间: 2018
• 期刊: Physical and Engineering Sciences
• 作者: Schaller, Morgan F.;Fung, Megan K.
• 通讯作者: Fung, Megan K.