Collaborative Research: East Antarctic Glacial Landscape Evolution (EAGLE): A Study using Combined Thermochronology, Geochronology and Provenance Analysis

合作研究：东南极冰川景观演化（EAGLE）：综合热年代学、地质年代学和起源分析的研究

• 批准号: 1443565
• 负责人: Sidney Hemming
• 金额: $ 26.69万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443565&HistoricalAwards=false
• 关键词: Collaborative; Research; East; Antarctic; Glacial

Antarctica is almost entirely covered by ice, in places over two miles thick. This ice hides a landscape that is less well known than the surface of Mars and represents one of Earth's last unexplored frontiers. Ice-penetrating radar images provide a remote glimpse of this landscape including ice-buried mountains larger than the European Alps and huge fjords twice as deep as the Grand Canyon. The goal of this project is to collect sediment samples derived from these landscapes to determine when and under what conditions these features formed. Specifically, the project seeks to understand the landscape in the context of the history and dynamics of the overlying ice sheet and past mountain-building episodes. This project accomplishes this goal by analyzing sand collected during previous sea-floor drilling expeditions off the coast of Antarctica. This sand was supplied from the continent interior by ancient rivers when it was ice-free over 34 million year ago, and later by glaciers. The project will also study bedrock samples from rare ice-free parts of the Transantarctic Mountains. The primary activity is to apply multiple advanced dating techniques to single mineral grains contained within this sand and rock. Different methods and minerals yield different dates that provide insight into how Antarctica?s landscape has eroded over the many tens of millions of years during which sand was deposited offshore. The dating techniques that are being developed and enhanced for this study have broad application in many branches of geoscience research and industry. The project makes cost-effective use of pre-existing sample collections housed at NSF facilities including the US Polar Rock Repository, the Gulf Coast Core Repository, and the Antarctic Marine Geology Research Facility. The project will contribute to the STEM training of two graduate and two undergraduate students, and includes collaboration among four US universities as well as international collaboration between the US and France. The project also supports outreach in the form of a two-week open workshop giving ten students the opportunity to visit the University of Arizona to conduct STEM-based analytical work and training on Antarctic-based projects. Results from both the project and workshop will be disseminated through presentations at professional meetings, peer-reviewed publications, and through public outreach and media.The main objective of this project is to reconstruct a chronology of East Antarctic subglacial landscape evolution to understand the tectonic and climatic forcing behind landscape modification, and how it has influenced past ice sheet inception and dynamics. Our approach focuses on acquiring a record of the cooling and erosion history contained in East Antarctic-derived detrital mineral grains and clasts in offshore sediments deposited both before and after the onset of Antarctic glaciation. Samples will be taken from existing drill core and marine sediment core material from offshore Wilkes Land (100°E-160°E) and the Ross Sea. Multiple geo- and thermo-chronometers will be employed to reconstruct source region cooling history including U-Pb, fission-track, and (U-Th)/He dating of zircon and apatite, and 40Ar/39Ar dating of hornblende, mica, and feldspar. This offshore record will be augmented and tested by applying the same methods to onshore bedrock samples in the Transantarctic Mountains obtained from the US Polar Rock Repository and through fieldwork. The onshore work will additionally address the debated incision history of the large glacial troughs that cut the range, now occupied by glaciers draining the East Antarctic Ice Sheet. This includes collection of samples from several age-elevation transects, apatite 4He/3He thermochronometry, and Pecube thermo-kinematic modeling. Acquiring an extensive geo- and thermo-chronologic database will also provide valuable new information on the poorly known ice-hidden geology and tectonics of subglacial East Antarctica that has implications for improving supercontinent reconstructions and understanding continental break-up.

南极洲几乎完全被冰覆盖，有些地方超过两英里厚。这些冰隐藏着一个比火星表面更不为人所知的景观，代表了地球上最后一个未被探索的边界之一。穿透冰层的雷达图像提供了对这一景观的远程一瞥，包括比欧洲阿尔卑斯山更大的冰封山脉和两倍于大峡谷深的巨大峡湾。 该项目的目标是收集来自这些景观的沉积物样本，以确定这些特征形成的时间和条件。 具体而言，该项目旨在了解覆盖冰盖和过去造山运动的历史和动态背景下的景观。 该项目通过分析以前在南极洲海岸进行海底钻探探险时收集的沙子来实现这一目标。这些沙子是由3400万年前无冰的古代河流从大陆内部提供的，后来又由冰川提供。该项目还将研究横贯南极山脉罕见的无冰部分的基岩样本。主要活动是将多种先进的测年技术应用于这些沙子和岩石中所含的单一矿物颗粒。不同的方法和矿物产生不同的日期，提供洞察如何南极洲？在数千万年的时间里，由于沙子沉积在近海，美国的地貌受到了侵蚀。为这项研究正在开发和改进的测年技术在地球科学研究和工业的许多分支中有广泛的应用。 该项目具有成本效益地利用了国家科学基金会设施中现有的样本收集，包括美国极地岩石储存库，墨西哥湾沿岸核心储存库和南极海洋地质研究设施。该项目将为两名研究生和两名本科生的STEM培训做出贡献，包括四所美国大学之间的合作以及美国和法国之间的国际合作。该项目还以为期两周的开放式研讨会的形式支持外展活动，让十名学生有机会访问亚利桑那大学，进行基于STEM的分析工作和基于舌的项目培训。该项目和讲习班的成果将通过专业会议上的介绍、同行评审的出版物以及通过公众宣传和媒体传播，该项目的主要目标是重建东南极冰下地貌演变年表，以了解地貌改变背后的构造和气候作用力，以及它如何影响过去冰盖的形成和动态。我们的方法的重点是获取记录的冷却和侵蚀的历史中所包含的东舌派生碎屑矿物颗粒和碎屑在近海沉积物中沉积的南极冰川作用开始之前和之后。将从威尔克斯地近海（100°E-160°E）和罗斯海现有的岩心和海洋沉积物岩心材料中取样。将采用多种地质和热计时器重建源区冷却历史，包括锆石和磷灰石的U-Pb、裂变径迹和（U-Th）/He定年，以及角闪石、云母和长石的40 Ar/39 Ar定年。通过将相同的方法应用于从美国极地岩石储存库获得的跨南极山脉的陆上基岩样品和通过实地工作，将对该海上记录进行增强和测试。陆上工作还将解决切割范围的大型冰川槽的有争议的切割历史，现在被冰川排出南极洲东部冰盖所占据。这包括收集样品从几个年龄海拔断面，磷灰石4 He/3 He thermochronometry，和Pecube热动力学建模。获得广泛的地质和热年代学数据库还将提供关于鲜为人知的冰下东南极洲的冰藏地质和构造的宝贵新信息，这对改善超大陆重建和了解大陆分裂具有影响。