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

学术价值拟议的工作将调查横跨南极山脉()与东南极出口冰川头部相邻的两个更新世冰川同心序列中冰盖成分随时间的变化情况。这项工作的年代学框架将根据突出的冰川脊上巨石的宇宙暴露年龄生成。PI假设冰层组成的变化可能表明冰流方向的变化或原始源区组成的变化，而冰雹的年龄则提供了对冰盖动力学的长期陆地视角。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。TIL组分随时间的变化也可以更准确地解释罗斯海和南大洋的沉积物岩心。此外，一些东南极出口冰川头部的裸露已被证明含有来自东南极基岩的冰下物质，这为透过冰层观看东南极-S难以接近的基岩提供了一个窗口。直到将从两个保存完好的冰河峰顶序列中收集样本。豪(斯科特冰川的负责人)和Mt.阿切尔纳(比尔德莫尔冰川和宁罗德冰川之间)。冰川冰川中的每个粒度组分提供了潜在的有价值的信息，PI将测量碎屑和砂组分的岩石学、粉碎的2 mm组分的定量X射线衍射、粉砂/粘土组分的元素丰度以及砂组分中碎屑锆石的U/Pb。数据收集将依赖以前在该区域使用的既定方法，私营部门还将探索新的方法来评估其效力。在同一批用于来源研究的冰雹峰顶上，生产者指数将抽样进行宇宙成因的表面暴露分析，以提供来源随时间变化的地点的年代学框架。更广泛的影响这项拟议的研究涉及对研究生和本科生进行各种实验室方法的培训。学生和PI将向社区和校园团体发表演讲，并接受当地新闻媒体的采访。这项拟议的工作还在IUPUI和LDEO的科学家之间建立了一种新的、可能长期的合作，并将一种新的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.