Collaborative Research: Pleistocene East Antarctic Ice Sheet History as Recorded in Sediment Provenance and Chronology of High-elevation TAM Moraines

智力优点拟议的工作将调查的变化，随着时间的推移，在成分变化的冰碛物在两个同心序列的更新世冰碛位于南极洲东部出口冰川的头附近的跨南极山脉（TAM）。这项工作的年代框架将产生从突出的冰碛脊的巨石宇宙成因暴露年龄。PI假设，直到组成的变化可能表明冰流方向的变化或原始源区的组成的变化，而冰碛的年龄提供了一个长期的冰盖动力学的陆地观点。这两个结果对于旨在重建东南极冰盖并评估其在全球气候系统中的作用及其对全球海平面上升的潜在影响的模拟实验至关重要。随着时间的推移，直到成分的变化也允许从罗斯海和南大洋的沉积物岩心更准确的解释。此外，一些东南极出口冰川头部的冰碛暴露已被证明含有来自东南极基岩的冰下物质，这提供了一个透过冰层观察东南极洲的窗口？难以接近的基岩。直到样品将收集两个保存完好的序列冰碛峰在山。豪（斯科特冰川的头）和山。阿切尔纳（Beardmore和尼姆罗德冰川之间）。冰川冰碛物中的每个粒度级都提供了潜在的有价值的信息，PI将测量碎屑和砂级的岩相学、压碎的2 mm级的定量X射线衍射、粉砂/粘土级的元素丰度以及砂级中碎屑锆石的U/Pb。数据收集将依赖于该地区以前使用的既定方法，PI还将探索评估其疗效的新方法。在为物源研究取样的同一冰碛峰上，PI将取样进行宇宙成因表面暴露分析，以提供物源随时间变化的地点的年表框架。更广泛的影响拟议的研究涉及研究生和本科生的培训，在一系列不同的实验室方法。学生和PI将向社区和校园团体做演讲，并接受当地新闻媒体的采访。拟议的工作还建立了IUPUI和LDEO科学家之间的新的，潜在的长期合作，并将一个新的PI（卡普兰）带入南极地球科学领域。

Intellectual Merit The proposed work will investigate changes in the compositional variation of glacial tills over time across two concentric sequences of Pleistocene moraines located adjacent to the heads of East Antarctic outlet glaciers in the Transantarctic Mountains (TAM). The chronologic framework for this work will be generated from cosmogenic exposure ages of boulders on prominent morainal ridges. The PIs hypothesize that variations in till composition may indicate a change in ice flow direction or a change in the composition of the original source area, while ages of the moraines provide a long-term terrestrial perspective on ice sheet dynamics. Both results are vital for modeling experiments that aim to reconstruct the East Antarctic Ice Sheet and assess its role in the global climate system and its potential impact on global sea level rise. The variation of till compositions through time also allows for a more accurate interpretation of sediment cores from the Ross Sea and the Southern Ocean. Additionally, till exposures at the head of some East Antarctic outlet glaciers have been shown to contain subglacial material derived from East Antarctic bedrock, providing a window through the ice to view East Antarctica?s inaccessible bedrock. Till samples will be collected from two well-preserved sequences of moraine crests at Mt. Howe (head of Scott Glacier) and Mt. Achernar (between Beardmore and Nimrod Glaciers). Each size fraction in glacial till provides potentially valuable information, and the PIs will measure the petrography of the clast and sand fractions, quantitative X-ray diffraction on the crushed 2mm fraction, elemental abundance of the silt/clay fraction, and U/Pb of detrital zircons in the sand fraction. Data collection will rely on established methods previously used in this region and the PIs will also explore new methods to assess their efficacy. On the same moraines crests sampled for provenance studies, the PIs will sample for cosmogenic surface exposure analyses to provide a chronologic framework at the sites for provenance changes through time. Broader Impact The proposed research involves graduate and undergraduate training in a diverse array of laboratory methods. Students and PIs will be make presentations to community and campus groups, as well as conduct interviews with local news outlets. The proposed work also establishes a new, potentially long-term, collaboration between scientists at IUPUI and LDEO and brings a new PI (Kaplan) into the field of Antarctic Earth Sciences.