Doctoral Dissertation Research: Deciphering Spatially and Temporally Complex High-Latitude Landscapes

博士论文研究：解读时空复杂的高纬度景观

• 批准号: 1433878
• 负责人: Paul Bierman
• 金额: $ 1.59万
• 依托单位: University of Vermont & State Agricultural College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1433878&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Deciphering; Spatially

High-latitude landscapes in the Arctic and Antarctic contain evidence of how the world's largest glaciers and ice sheets have responded to past changes in climate, and they document how glaciers erode and transport sediments and nutrients. This doctoral dissertation research project will examine an area of northwestern Greenland as a natural laboratory that can be used to study high-latitude landscape evolution on timescales of tens to hundreds of thousands of years. The doctoral student will analyze two distinct units of glacial sediments that have been deposited in different but adjacent areas in the Thule region in order to determine how each of the sedimentary units has evolved over space and time and use these insights as a model for understanding landscape evolution and sediment transport in glaciated high-latitude regions, including locations in northern North America and other high-latitude landscapes where similar processes are functioning. The project will provide valuable new information about the timing of past episodes of ice sheet advance and retreat. It will help address the question of whether glacial ice has behaved as an agent of erosion, and it will enhance scientific understanding of the complex processes that shape high-latitude landscapes. Cosmogenic data will be made accessible to other researchers via the NOAA paleoclimatology database, and project findings will be disseminated through both scholarly and popular media in order to broaden the range of individuals who may benefit from the new insights and information that will be generated. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.The high-latitude landscapes that are the focus of this project are shaped by a cyclic pattern of glacial advance and retreat. During glacial periods, when ice sheets expand, the landscape can either be deeply eroded and sculpted by glacial ice (if the ice is at the melting point and liquid water is available) or preserved beneath non-erosive glacial ice (if the ice is below the melting point and frozen to the bed). During interglacial periods when ice sheets shrink, weathering modifies the landscape through movement of material by wind, water, and freeze-thaw action. Subsequent smaller ice advances may cover only part of the landscape, creating geographies where surfaces with different ages and histories are juxtaposed. The doctoral student will reconstruct the complex landscape history in the Thule region through the analysis of three rare isotopes: beryllium-10, aluminum-26, and carbon-14. These isotopes build up slowly in rock surfaces only when the rocks are exposed and not covered by glaciers. The analyses of the concentrations of these isotopes in rock surfaces will provide information about the age and exposure history of the landscape.

北极和南极的高纬度景观包含了世界上最大的冰川和冰盖如何对过去的气候变化做出反应的证据，它们记录了冰川如何侵蚀和运输沉积物和营养物质。这个博士论文研究项目将研究格陵兰岛西北部的一个地区，作为一个自然实验室，可以用来研究几万到几十万年时间尺度上的高纬度景观演变。博士生将分析两个不同的冰川沉积物单元，它们沉积在图勒地区不同但相邻的区域，以确定每个沉积单元是如何随着空间和时间的推移而演变的，并将这些见解作为理解冰川高纬度地区景观演变和沉积物运输的模型，包括北美北部和其他高纬度地区，那里的类似过程正在起作用。该项目将提供有关过去冰盖前进和后退时间的宝贵新信息。它将有助于解决冰川冰是否作为侵蚀因素的问题，并将加强对塑造高纬度景观的复杂过程的科学理解。宇宙起源数据将通过NOAA古气候学数据库提供给其他研究人员，项目结果将通过学术和大众媒体传播，以扩大可能从将产生的新见解和信息中受益的个人范围。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。高纬度的景观是这个项目的重点，是由冰川前进和后退的循环模式塑造的。在冰期，当冰盖扩张时，景观要么被冰川冰（如果冰在熔点并且有液态水可用）深深侵蚀和雕刻，要么被保存在非侵蚀性冰川冰（如果冰在熔点以下并冻结到床上）之下。在间冰期，当冰原收缩时，风化作用通过风、水和冻融作用的物质运动改变了景观。随后较小的冰的移动可能只覆盖了部分景观，形成了不同年龄和历史的表面并列的地理位置。该博士生将通过分析三种稀有同位素：铍-10、铝-26和碳-14，重建图勒地区复杂的景观历史。这些同位素只有在岩石暴露而没有被冰川覆盖时才会在岩石表面缓慢积累。对岩石表面这些同位素浓度的分析将提供有关景观年龄和暴露历史的信息。