Age and Composition of the East Antarctic Shield by Isotopic Analysis of Granite and Glacial Till

智力优势：由于广阔的冰盖和稀少的遥感数据，前寒武纪东南极盾(EAS)的地质在很大程度上仍未得到勘探，信息仅限于非洲、印度和澳大利亚部分的沿海露头。东南极岩石圈具有全球重要性：作为最大的连贯前寒武纪地幔之一，包括早至3.8Ga的岩石，在全球地壳增长中发挥了重要作用；它是罗迪尼亚和冈瓦那超大陆组装的关键部分；它是地球的基底？S主要的冰盖，包括许多冰下湖泊，并影响其热状态和机械稳定性；它与南非、印度和澳大利亚以前毗邻的大陆块的大地构造组合表明，它可能拥有重要的矿产资源。该项目将增加对横贯南极山脉()之下和毗邻的西部东亚地区岩石圈的年龄和组成的了解，利用U-Pb年龄和早古生代花岗岩类和更新世冰川中锆石的Hf和O同位素分析。早古生代罗斯造山带的花岗岩代表了一套面积广泛的大陆边缘弧系，可以提供有关其熔融和/或穿过的EAS地壳的直接信息。穿过的主要出口冰川头部的冰川冰层中夹带着大量火成岩和变质岩性的岩石碎屑，提供了东亚近岸基底的侵蚀样品。这些材料中的锆石将提供有关年龄和继承性(U-Pb)、地壳与地幔起源(氧同位素)以及地壳来源和演化(Hf同位素)的数据。这些数据整合在山脉的一个重要部分，将有助于确定更广泛的地壳省份，这些省份可以与地球物理数据相关联，并用于检验地壳组装的模型。更广泛的影响：这个项目将为本科生和研究生提供一个研究机会。本科生将作为研究助理参与样品准备、成像和分析程序，并进行自己的独立研究。这个项目的两个主要要素将构成UMD两名研究生的硕士论文项目的基础。通过这个项目，他们将对岩石学、同位素地球化学和分析方法有很好的了解。这项工作的更广泛的科学影响是，它将有助于更好地了解之下和邻近的东南极岩石圈的起源和演化，这将对更广泛的地球科学界和冰川界具有价值。此外，由于对过去的超大陆、冰层下的S以及全球变暖对冰盖稳定性的影响有强烈的好奇心，东南极地质知识继续引起公众的兴趣。

Intellectual Merit: Because of extensive ice cover and sparse remote-sensing data, the geology of the Precambrian East Antarctic Shield (EAS) remains largely unexplored with information limited to coastal outcrops from the African, Indian and Australian sectors. The East Antarctic lithosphere is globally important: as one of the largest coherent Precambrian shields, including rocks as old as ~3.8 Ga, it played an important role in global crustal growth; it is a key piece in assembly of the Rodinia and Gondwana supercontinents; it is the substrate to Earth?s major ice cap, including numerous sub-glacial lakes, and influences its thermal state and mechanical stability; and its geotectonic association with formerly adjacent continental blocks in South Africa, India and Australia suggest that it might harbor important mineral resources. This project will increase understanding of the age and composition of the western EAS lithosphere underlying and adjacent to the Transantarctic Mountains (TAM) using U-Pb ages, and Hf- and O-isotope analysis of zircon in early Paleozoic granitoids and Pleistocene glacial tills. TAM granites of the early Paleozoic Ross Orogen represent an areally extensive continental-margin arc suite that can provide direct information about the EAS crust from which it melted and/or through which it passed. Large rock clasts of igneous and metamorphic lithologies entrained in glacial tills at the head of major outlet glaciers traversing the TAM provide eroded samples of the proximal EAS basement. Zircons in these materials will provide data about age and inheritance (U-Pb), crustal vs. mantle origin (O isotopes), and crustal sources and evolution (Hf isotopes). Integrated along a significant part of the TAM, these data will help define broader crustal provinces that can be correlated with geophysical data and used to test models of crustal assembly. Broader impacts: This project will provide a research opportunity for undergraduate and graduate students. Undergraduates will be involved as Research Assistants in sample preparation, imaging, and analytical procedures, and conducting their own independent research. The two main elements of this project will form the basis of MS thesis projects for two graduate students at UMD. Through this project they will gain a good understanding of petrology, isotope geochemistry, and analytical methods. The broader scientific impacts of this work are that it will help develop a better understanding of the origin and evolution of East Antarctic lithosphere underlying and adjacent to the TAM, which will be of value to the broader earth science and glaciological community. Furthermore, knowledge of East Antarctic geology is of continuing interest to the general public because of strong curiosity about past supercontinents, what?s under the ice, and the impact of global warming on ice-sheet stability.