Ancient landscape-active Surfaces: Periglacial Hyperinflation in soils of Beacon Valley, Antarctica

知识价值：该项目将通过测量在南极洲比肯谷采集的两个独特的永久冻土岩心中石英砂中的宇宙成因核素，获得有关南极长期气候和景观演变的新信息。这两个岩心已经在5.5米和30.6米深的冰固化、富含沙子的永久冻土中钻出，目前在华盛顿大学冷藏。这些岩心被认为记录了沙子的单调堆积，这些沙子被吹到比肯山谷下游，并随着时间的推移而膨胀。人们认为，积累的速度和任何积累的中断都部分地反映了泰勒冰川的前进和后退。在5.5米深的岩心中，对石英砂中宇宙产生的铍（10Be）和铝（26Al）的初步测量表明，在过去的100万年里，石英砂一直以2.5米/迈尔的速度增长。此外，在此之前，下灯塔谷很可能被泰勒冰川覆盖（从大气中屏蔽，因此没有或非常低的宇宙核素在石英中产生），从1到3.5 Myr BP。这些初步测量还表明，30.6米的地核可能提供了超过1000万年的记录。重点是在30.6米的永久冻土层核心中对核心进行全面表征和宇宙成因核素（包括宇宙成因氖）的分析，以发展沙子的埋藏历史，并可能记录泰勒冰川的盛衰。这将允许对我们目前对麦克默多干谷（MDV）地表动力学和气候历史的理解进行新的测试，这些理解是基于数百万年来在地表积累和膨胀的风成沙的年代地层。这是一个新的地表膨胀过程，其程度尚未得到很好的记录，并有可能发展成一个连续的地表埋藏和冰川扩张的历史。该项目将为了解干谷的气候历史提供一个新的代理，并将测试比肯谷永久冻土演变的模型。更广泛的影响：麦克默多干谷的景观历史很重要，因为那里的地质沉积物包含了南极洲最丰富的陆地记录。通过测试这些沉积物的当前年龄模型，我们将提高对南极洲的了解。美国在全球气候变化中的作用。本项目将培养地球化学、地质年代学、冰川与冰缘地质学各1名研究生和1名本科生。他们将实质性地参与研究，并期望他们发展自己的原创想法。这项工作的结果将被纳入本科和研究生的教学课程，将发表在同行评审的文献中，并将公布数据。

Intellectual Merit: This project will yield new information on the long term Antarctic climate and landscape evolution from measurements of cosmogenic nuclides in quartz sand from two unique permafrost cores collected in Beacon Valley, Antarctica. The two cores have already been drilled in ice-cemented, sand-rich permafrost at 5.5 and 30.6 meters depth, and are currently in cold storage at the University of Washington. The cores are believed to record the monotonic accumulation of sand that has been blown into lower Beacon Valley and inflated the surface over time. The rate of accumulation and any hiatus in the accumulation are believed to reflect in part the advance and retreat of the Taylor Glacier. Preliminary measurements of cosmogenically-produced beryllium (10Be) and aluminum (26Al) in quartz sand in the 5.5 meter depth core reveal that it has been accreting at a rate of 2.5 meter/Myr for the past million years. Furthermore, prior to that time, lower Beacon Valley was most likely covered (shielded from the atmosphere thereby having no or very low production of cosmogenic nuclides in quartz) by Taylor Glacier from 1 to 3.5 Myr BP. These preliminary measurements also suggest that the 30.6 meter core may provide a record of over 10 million years. The emphasis is the full characterization of the core and analysis of cosmogenic nuclides (including cosmogenic neon) in the 30.6 meter permafrost core to develop a burial history of the sands and potentially a record the waxing and waning of the Taylor Glacier. This will allow new tests of our current understanding of surface dynamics and climate history in the McMurdo Dry Valleys (MDV) based on the dated stratigraphy of eolian sand that has been accumulating and inflating the surface for millions of years. This is a new process of surface inflation whose extent has not been well documented, and holds the potential to develop a continuous history of surface burial and glacial expansion. This project will provide a new proxy for understanding the climatic history of the Dry Valleys and will test models for the evolution of permafrost in Beacon Valley.Broader impacts: The landscape history of the McMurdo Dry Valleys is important because geological deposits there comprise the richest terrestrial record available from Antarctica. By testing the current age model for these deposits, we will improve understanding of Antarctica?s role in global climate change. This project will train one graduate and one undergraduate student in geochemistry, geochronology, and glacial and periglacial geology. They will participate substantively in the research and are expected to develop their own original ideas. Results from this work will be incorporated into undergraduate and graduate teaching curricula, will be published in the peer reviewed literature, and the data will be made public.