Collaborative Research: Linking Marine and Terrestrial Sedimentary Evidence for Plio-pleistocene Variability of Weddell Embayment and Antarctic Peninsula Glaciation

南极冰盖和冰川融化和崩塌导致未来海平面上升的可能性令人担忧。通过研究冰盖在过去气候中的表现，特别是在与现在相似或更温暖的条件下，我们可以增进对南极冰盖和海洋之间水如何交换的理解。在这个项目中，研究小组将结合南极半岛附近地点冰川变化的海洋和陆地证据，并辅之以关于环境变化的时间尺度和化石证据的详细工作，记录地球从温暖的上新世过渡到更新世冰河时代期间南极洲的反应。一个重要的目标是测试随着地球最近的冰河时代的加剧，南极洲的冰川是否与北半球的冰川同时发生变化，或者对南半球的区域气候强迫做出反应。来自七个美国机构的 11 名研究人员以及阿根廷合作者将研究国际海洋发现计划的新沉积岩芯，以及该计划的遗留岩芯和詹姆斯罗斯岛的陆地露头。该小组采用垂直整合的研究计划，允许高中、本科生、研究生、博士后和教师在同一项目上合作。这种结构利用了近同行指导和强大的协作研究网络的发展的优势，同时允许所有参与者拥有项目的不同部分。该团队的所有成员都坚定地致力于吸引来自代表性不足群体的研究人员，并将通过现有渠道以及共同创建的项目来做到这一点，该项目将不同学生的观点集中在有关海平面上升和气候变化的对话中。拟议的研究旨在了解北半球和南半球冰川与气候变化之间的阶段性，作为了解驱动因素和遥相关的一种手段。过去南极冰川作用的动力学可以使用来自冰川部分的独特同位素地球化学和矿物学指纹来研究，这些指纹与地层序列的严格约束时间模型相关。拟议的工作将通过耦合生物地层学和磁性地层学工作进一步完善地层背景。冰山崩解的规模和冰山路径将通过冰筏碎屑的通量、地球化学和矿物学特征以及 40Ar/39Ar 和 U-Pb 地质年代学来揭示。这些溯源器将确定南极洲冰盖的哪些部分更容易崩塌，并且这些事件的时间和节奏将通过其地层背景来揭示。此外，该团队将与阿根廷合作者合作，通过研究詹姆斯罗斯岛上夹有火山流的冰川记录，将海洋和陆地记录联系起来。这些新的约束将与最先进的冰盖模型相结合，将冰动力学的变化与其根本原因联系起来。总之，这些严格的地层限制、地球化学特征和冰盖模型模拟将提供一种方法来与全球气候变化记录进行比较，了解其主要驱动因素，并阐明南极冰盖在从上新世到更新世的重大全球气候转变中的作用。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。

The potential for future sea level rise from melting and collapse of Antarctic ice sheets and glaciers is concerning. We can improve our understanding of how water is exchanged between Antarctic ice sheets and the ocean by studying how ice sheets behaved in past climates, especially conditions that were similar to or warmer than those at present. For this project, the research team will document Antarctica’s response across an interval when Earth transitioned from the warm Pliocene into the Pleistocene ice ages by combining marine and land evidence for glacier variations from sites near the Antarctic Peninsula, complimented by detailed work on timescales and fossil evidence for environmental change. An important goal is to test whether Antarctica’s glaciers changed at the same time as glaciers in the Northern Hemisphere as Earth's most recent Ice Age intensified, or alternatively responded to regional climate forcing in the Southern Hemisphere. Eleven investigators from seven US institutions, as well as Argentine collaborators, will study new sediment cores from the International Ocean Discovery Program, as well as legacy cores from that program and on-land outcrops on James Ross Island. The group embraces a vertically integrated research program that allows high school, undergraduate, graduate, post-docs and faculty to work together on the same projects. This structure leverages the benefits of near-peer mentoring and the development of a robust collaborative research network while allowing all participants to take ownership of different parts of the project. All members of the team are firmly committed to attracting researchers from under-represented groups and will do this through existing channels as well as via co-creating programming that centers the perspectives of diverse students in conversations about sea-level rise and climate change.The proposed research seeks to understand phasing between Northern and Southern Hemisphere glacier and climate changes, as a means to understand drivers and teleconnections. The dynamics of past Antarctic glaciation can be studied using the unique isotope geochemical and mineralogic fingerprints from glacial sectors tied to a well-constrained time model for the stratigraphic successions. The proposed work would further refine the stratigraphic context through coupled biostratigraphic and magnetostratigraphic work. The magnitude of iceberg calving and paths of icebergs will be revealed using the flux, geochemical and mineralogic signatures, and 40Ar/39Ar and U-Pb geochronology of ice-rafted detritus. These provenance tracers will establish which sectors of Antarctica’s ice sheets are more vulnerable to collapse, and the timing and pacing of these events will be revealed by their stratigraphic context. Additionally, the team will work with Argentine collaborators to connect the marine and terrestrial records by studying glacier records intercalated with volcanic flows on James Ross Island. These new constraints will be integrated with a state of the art ice-sheet model to link changes in ice dynamics with their underlying causes. Together, these tight stratigraphic constraints, geochemical signatures, and ice-sheet model simulations will provide a means to compare to the global records of climate change, understand their primary drivers, and elucidate the role of the Antarctic ice sheet in a major, global climatic shift from the Pliocene into the Pleistocene.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.