History of the East Antarctic Ice Sheet since the mid-Miocene: New Evidence from Provenance of Ice-rafted Debris

学术价值：PIS建议研究威尔克斯和奥罗拉冰下盆地地区上新世南极东部冰盖的稳定性和动力学。模型表明，这些低洼地区的冰盖对气候变暖最为敏感。这项研究很重要，因为很少有直接证据表明东南极冰盖的哪些部分在温暖的条件下变得不稳定。在一项初步研究中，PIs表明，核下部冰筏碎片(IRD)的同位素地球化学特征可以与大陆源区联系起来，表明冰盖的哪些部分到达海岸并崩解了携带IRD的冰山。他们的初步结果表明，在中新世晚期和上新世早期，威尔克斯陆地和阿德利陆地沿海地区的冰山有时会迅速排出。在这项研究中，PI将从南极东部外大陆隆起收集的IODP沉积岩芯中分析IRD。通过分析角闪石IRD颗粒的40Ar/39Ar年龄，锆石的U-Pb年龄，以及每个核的几个IRD富集层的细小部分的Sm-ND同位素，他们将能够对大陆源区进行指纹识别，这将指示南极东部的冰范围和动力学。PI还将在其中几个层上进行详细研究，以确定冰筏事件的解剖特征，并更好地了解冰破坏的机制。广泛影响：收集的数据将对广泛领域的科学家非常重要。该项目将涉及LDEO的一名本科生和一名暑期实习生，以及伦敦帝国理工学院的一名研究生。该项目将接触到尖端方法和国际研究团队。该项目的数据将存入在线数据库(SedDB)，所有结果和方法将通过在同行评议的期刊上发表文章和参加国际会议向科学界提供。

Intellectual Merit: The PIs propose to study the stability and dynamics of the East Antarctic ice sheet during the Pliocene in the area of the Wilkes and Aurora subglacial basins. Models indicate the ice sheet is most sensitive to warming in these low-lying areas. This study is important as there is very little direct evidence about which parts of the East Antarctic ice sheet became unstable under warm conditions. In a pilot study the PIs have shown that the isotopic geochemical signature of downcore ice-rafted debris (IRD) can be linked to continental source areas indicating which parts of the ice sheet reached the coast and calved IRD-bearing icebergs. Their initial results suggest rapid iceberg discharge from the Wilkes Land and Adélie Land coastal areas at times in the late Miocene and early Pliocene. In this study the PIs will analyze IRD from IODP sediment cores collected on the continental rise off East Antarctica. By analyzing 40Ar/39Ar ages of hornblende IRD grains, U-Pb ages of zircons, and Sm-Nd isotopes of the fine fraction of several IRD-rich layers for each core, they will be able to fingerprint continental source areas that will indicated ice extent and dynamics on East Antarctica. The PIs will also carry out detailed studies across a few of these layers to characterize the anatomy of the ice-rafting event and better understand the mechanism of ice destabilization.Broader impacts: The data collected will be important for scientists in a broad variety of fields. The project will involve one undergraduate student and one summer intern at LDEO, and a graduate student at Imperial College London. The project will expose to cutting edge methodologies as well as an international research team. Data from the project will be deposited in the online databases (SedDB) and all results and methods will be made available to the scientific community through publications in peer-reviewed journals and attendance at international conferences.