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

外星人的撞击在塑造这个星球上生命的进化方面发挥了重要作用。2016年，发现了一次撞击事件的证据，该事件与5600万年前在古新世-始新世(P-E)边界发生的一次重大气候事件重合。证据包括从撞击现场抛出的特有的玻璃球体和受冲击的矿物颗粒(称为抛射物)。在P-E边界发生地外撞击的第一个确凿证据提出了许多问题，如源陨石坑的潜在位置、散布区域的范围和物质的确切年龄。该项目将通过对P-E边界完整的已知地点的沉积物进行广泛搜索，并通过对物质进行放射性测年，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，并伴随着5-8摄氏度的全球变暖。了解这一事件周围的条件很重要，因为它是对我们当前人为碳排放和气候变化的最佳地质模拟，而且无论触发机制如何，它都为我们提供了未来可能发生的事情的路线图。这段时间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边界撞击事件的情况将极大地促进我们对过去5600万年来生命和气候演变的科学理解。该项目的更广泛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。这项研究建立在大西洋沿岸平原P-E边界的外星人撞击喷射物和佛罗里达州布莱克鼻部沉积物的最新发现基础上。喷出物质是在标志着全球P-E边界的负碳同位素漂移(CIE)开始时发现的。这项研究的研究方法类似于寻找白垩纪-古近纪(K-PG)边界撞击坑，最终导致发现了希克苏鲁布撞击地点。该项目旨在为P-E边界提供第一个放射性测年和潜在的全球基准标记。预期成果包括：1)P-E影响区域的散布场图和位置；2)使用40Ar/39Ar方法确定P-E边界的辐射年龄；3)建立P-E喷发作为精确的时间视界和对比工具；以及4)未来研究的框架(A)处理P-E影响和P-E气候扰动之间的任何因果联系，以及(B)评估P-E生物和气候变化与全球观测的CIE的精确时间。在P-E边界发生的气候和生物变化是巨大的；例如，最终导致人类的灵长类谱系在这一边界出现，深海变化导致底栖海洋微型动物大规模灭绝。因此，如果外星撞击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就是至关重要的观察。

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.