Collaborative Research: EAR Climate: Earth-System Responses to the Penultimate Icehouse-Greenhouse Transition

大约3亿年前，随着地球气候在冰期和间冰期之间交替，高纬度地区的大型冰川和冰盖起伏不定，延续了数百万年的模式。然而，不久之后，冰川完全崩溃，地球系统从无冰状态摇摇晃晃地进入日益严峻的“温室”气候，这在很大程度上是由温室气体向大气中大规模和持续释放提供动力，最终导致地球历史上已知的最大规模的生命灭绝。这个项目将通过从当时的地球赤道地区，即现在的美国中大陆(俄克拉何马州)恢复和研究一个2000米长的岩芯，来检验这种戏剧性转变的完整记录。主要目标是揭示这些极端环境变化的驱动力，揭示地球系统(地圈-大气层-生物圈的联系)在前所未有的剧变期间的基本工作原理。除了国际合作者外，该项目还将涉及俄克拉荷马州和其他地区的美国原住民青年、教育家、科学家、艺术家和诗人。该项目旨在阐明古环境、生物地球化学循环以及地球和生命演化的关键时期二叠纪期间陆地生物圈对气候强迫的响应。将在阿纳达科盆地(俄克拉荷马州)钻探岩心，阿纳达科盆地是一个深陆相盆地，保存着赤道盘古大陆二叠纪的全球独特和地层完整的档案。保存完好的近海到大陆的过渡被一系列红层、古黄土/灰尘、湖泊和蒸发岩沉积所覆盖，这些沉积共同记录了晚古生代冰河时代的消亡和日益加剧的温室气候，最终导致了地球历史上最严重的大规模灭绝。该项目将通过整合U-Pb地质年代学、天体年代学、磁性地层学和生物地层学来建立高分辨率年代地层学框架。由此产生的框架将作为后续研究的脚手架，旨在测试假设，重点是气候、造山和生物变化之间的相互关系，在一个以明显的地球系统剧变为特征的时期。这项研究解决了与地球过去和未来有关的重大问题，因为它将阐明各种机制联系，例如，大气尘埃、气候、山脉和正在经历从冷到热气候转变的地球生物圈之间的联系。由于尘埃在地球系统中的作用已知的重要性，但极大的不确定性，对这些联系的探索将可测量地扩大对整个显生界地球系统行为的了解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

About 300 million years ago, large glaciers and ice sheets at high latitudes waxed and waned as Earth’s climate alternated between glacial and interglacial states, continuing a pattern that had persisted for several millions of years. Shortly thereafter, however, the glaciers collapsed entirely, and the Earth system lurched beyond an ice-free state into an increasingly severe “hothouse” climate, powered in large part by a massive and sustained release of greenhouse gases into the atmosphere, ultimately culminating in the largest extinction of life known in Earth history. This project will examine a complete record of this dramatic transition by recovering and studying a 2000 m-long rock core from what was, at that time, the equatorial region of the planet, which is now the US midcontinent (Oklahoma). The principal goal is to uncover the driving forces for these extreme environmental changes, shedding light on the fundamental workings of the Earth system (geosphere-atmosphere-biosphere connections) during an interval of unprecedented upheaval. This project involves many students and early-career researchers across twelve US research institutions, in addition to international collaborators, and additionally will engage Native American youth, educators, scientists, artists and poets in Oklahoma and beyond.This project seeks to elucidate paleoenvironments, biogeochemical cycling, and responses of the terrestrial biosphere to climate forcing during the Permian Period, a critical time in the evolution of Earth and life. A drill core will be taken in the Anadarko Basin (Oklahoma), which is a deep continental basin that preserves a globally unique and stratigraphically complete archive of the continental Permian in equatorial Pangaea. A well-preserved paralic-to-continental transition is overlain by a succession of red-bed, paleo-loess/dust, lacustrine, and evaporite deposits that collectively record the demise of the Late Paleozoic Ice Age and an intensifying greenhouse climate, culminating in the most severe mass extinction in Earth history. The project will establish a high-resolution chronostratigraphic framework by integrating U-Pb geochronology, astrochronology, magnetostratigraphy, and biostratigraphy. The resulting framework will serve as the scaffolding for subsequent research designed to test hypotheses focused on the interrelationships among climatic, orogenic, and biotic changes during an interval characterized by pronounced Earth-system upheavals. This research addresses major questions relevant to both Earth’s past and its future, as it will elucidate various mechanistic linkages, e.g. among atmospheric dust, climate, mountains, and the biosphere on an Earth experiencing a cold-to-hot climate transition. Owing to the known importance but great uncertainty of the role of dust in the Earth system, exploration of these links will measurably expand the knowledge of Earth system behavior across the Phanerozoic.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.