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

大约三亿年前，随着地球气候在冰川期和间冰期状态之间交替，高纬度地区的大型冰川和冰盖不断增减，延续了已经持续了数百万年的模式。然而不久之后，冰川完全崩塌，地球系统从无冰状态转向日益严峻的“温室”气候，这在很大程度上是由大量持续向大气中释放的温室气体推动的，最终导致了地球历史上已知的最大规模的生命灭绝。该项目将通过恢复和研究当时地球赤道地区（现在的美国中部大陆（俄克拉荷马州））的 2000 米长的岩芯来检查这一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，揭示地球系统在前所未有的剧变期间的基本运作方式（地圈-大气-生物圈连接）。该项目涉及美国十二个研究机构的许多学生和早期职业研究人员以及国际合作者，此外还将吸引俄克拉荷马州及其他地区的美国原住民青年、教育工作者、科学家、艺术家和诗人。该项目旨在阐明二叠纪时期（地球和生命进化的关键时期）的古环境、生物地球化学循环以及陆地生物圈对气候强迫的反应。钻探岩芯将在阿纳达科盆地（俄克拉荷马州）采集，该盆地是一个深层大陆盆地，在赤道盘古大陆中保存着全球独特且地层完整的大陆二叠纪档案。保存完好的陆陆过渡带被一系列红层、古黄土/尘埃、湖泊和蒸发岩沉积物覆盖，这些沉积物共同记录了晚古生代冰河时代的消亡和温室气候的加剧，最终导致地球历史上最严重的大规模灭绝。该项目将整合U-Pb地质年代学、天文年代学、磁性地层学和生物地层学，建立高分辨率年代地层框架。由此产生的框架将作为后续研究的框架，旨在检验以地球系统明显剧变为特征的时期内气候、造山和生物变化之间相互关系的假设。这项研究解决了与地球的过去和未来相关的主要问题，因为它将阐明各种机械联系，例如。正在经历从冷到热气候转变的地球上的大气尘埃、气候、山脉和生物圈。由于尘埃在地球系统中的作用的重要性众所周知，但具有很大的不确定性，对这些联系的探索将大大扩展对显生宙地球系统行为的了解。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。

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.