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

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应对过去气候变化的证据，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，可用于研究高纬度景观演化的时间尺度为数万至数十万年。 该博士生将分析沉积在图勒地区不同但相邻区域的两个不同的冰川沉积物单元，以确定每个沉积单元如何随时间和空间演变，并将这些见解作为理解景观演变和沉积物运输的模型。包括在北方北美和其它高纬度地区的位置，在那里类似的过程正在起作用。 该项目将提供有关过去冰盖进退时间的宝贵新信息。 它将有助于解决冰川冰是否是侵蚀的媒介的问题，并将加强对塑造高纬度景观的复杂过程的科学理解。 宇宙成因数据将通过诺阿古气候学数据库提供给其他研究人员，项目研究结果将通过学术和大众媒体传播，以扩大可能受益于新的见解和信息的个人范围。 作为博士论文研究改进奖，该奖项还将为有前途的学生提供支持，使其能够建立强大的独立研究事业。该项目的重点是高纬度景观，由冰川进退的循环模式塑造。 在冰川期，当冰盖扩张时，景观可以被冰川冰（如果冰处于熔点并且有液态水）深深侵蚀和雕刻，或者保存在非侵蚀性冰川冰下（如果冰低于熔点并冻结在床上）。 在间冰期，当冰盖收缩时，风化作用通过风、水和冻融作用引起的物质运动来改变景观。 随后较小的冰的进展可能只覆盖了部分景观，创造了不同年龄和历史的表面并置的地理位置。 博士生将通过三种稀有同位素的分析重建图勒地区复杂的景观历史：铍-10，铝-26和碳-14。 只有当岩石暴露在外而没有被冰川覆盖时，这些同位素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的年龄和暴露历史的信息。

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.