Doctoral Dissertation Research: Late Pleistocene Glaciation in Southeastern Alaska: Assessing the Sensitivity of a Marine-Terminating Ice Sheet to Changing Environmental Conditions

博士论文研究：阿拉斯加东南部更新世晚期冰川作用：评估海洋终止冰盖对环境条件变化的敏感性

• 批准号: 1657065
• 负责人: Jason Briner
• 金额: $ 1.6万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1657065&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Late; Pleistocene

This doctoral dissertation research project will integrate glacial geology, detailed ice-margin mapping, and high-resolution geochronology to assess the influence of climate and topography on the extent and retreat of a marine margin of the Cordilleran Ice Sheet is southeastern Alaska. This project will provide new insights into the processes that control the stability of marine ice-sheet margins. It will yield a direct chronology of a western Cordilleran Ice Sheet retreat along a marine margin, thereby facilitating reconstructions of this part of the ice sheet and adding to knowledge about the spatial and temporal relationships among climate, topography, and ice-sheet extent. This project will generate new insights into the processes that control the stability of marine ice sheet margins and provide empirical constraints to improve predictive models of the ice sheet-climate system. In addition, the project will provide direct evidence of ice-free conditions in previously proposed coastal ice-free areas along the Pacific Rim of North America that will have important implications for analyses of human migrations into the Americas. Project results will be incorporated into an outreach program conducted in concert with the Buffalo Museum of Science that synthesizes current research in geography, paleoclimatology, anthropology, and paleontology to educate the public about the causes and consequences of changing environmental conditions. 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.Marine ice-sheet margins, including those in present-day Greenland and Antarctica, are thought to be highly sensitive to climatic variation, but the effects of environmental change on marine ice sheet margins are still poorly understood. During the Last Glacial Maximum (roughly 26,000 to 19,000 years ago), the Cordilleran Ice Sheet covered much of western North America, stretching from southern Alaska to the Pacific Northwest of the U.S. Relatively little is known about Cordilleran Ice Sheet behavior during this time period, particularly along the west coast where it terminated in the ocean. This project will focus on three sets of research questions concerning the behavior of the western Cordilleran Ice Sheet during and following the Last Glacial Maximum: (1) How extensive was the Cordilleran Ice Sheet in southeastern Alaska during the Last Glacial Maximum, and did any areas of southeastern Alaska remain ice-free? This question will be addressed using cosmogenic exposure dating of the beryllium-10 isotope bedrock and boulder surfaces in previously proposed ice-free areas. Together with detailed mapping of the paleo-ice margin from publicly available topographic data and aerial imagery, exposure ages from these locations will allow the doctoral student to reconstruct the maximum extent of the western Cordilleran Ice Sheet. (2) What was the timing and pace of retreat of the western Cordilleran Ice Sheet? Cosmogenic beryllium-10 dating of rock surfaces along coast-to-inland transects will be used to resolve this question, which has implications for basic understanding of the sensitivity of marine-terminating ice sheets to climate change. (3) What environmental factors, such as ocean warming, atmospheric warming, and sea-level rise, influenced ice-sheet retreat? The retreat chronology developed in this study will be correlated with existing climate and sea-level records to test the hypothesis that ocean warming was the primary factor influencing marine ice-sheet collapse in southeastern Alaska.

该博士学位论文研究项目将整合冰川地质，详细的冰块映射以及高分辨率的地质学，以评估气候和地形在Cordilleran冰盖海洋边缘的范围和撤退的影响下，是阿拉斯加东南部。 该项目将为控制海洋冰盖边缘稳定性的过程提供新的见解。 它将产生沿海洋边缘的西部山脉冰盖撤退的直接年代，从而促进了这部分冰盖的重建，并增加了有关气候，地形和冰状范围之间的空间和时间关系的知识。 该项目将对控制海洋冰盖边缘稳定性的过程产生新的见解，并提供经验约束，以改善冰原气候系统的预测模型。 此外，该项目将在北美太平洋沿线的先前提议的无沿冰冰区域提供无冰条件的直接证据，这将对人类移民到美洲的分析具有重要意义。 项目结果将纳入与布法罗科学博物馆共同开展的外展计划中，该计划综合了当前的地理，古气候学，人类学和古生物学研究，以教育公众关于不断变化的环境条件的原因和后果。 作为博士学位论文研究改进奖，该奖项还将提供支持，使有前途的学生能够建立强大的独立研究职业。包括当今格陵兰和南极洲的海上冰页边缘，人们认为对气候变化非常敏感，但是环境变化对海洋冰盖边缘的影响仍然很糟糕。 在最后的冰川最大值（大约26,000至19，000年前）中，Cordilleran冰盖覆盖了北美西部的大部分地区，从阿拉斯加南部到美国的西北太平洋延伸，关于这段时期内的山脉冰盖行为，尤其是在西海岸，尤其是在海洋中终止的西海岸。 该项目将重点介绍有关最后一次冰川最大冰川期间和之后的西部山脉冰盖行为的三组研究问题：（1）在最后一次冰川最大的最大冰川期间，阿拉斯加东南部的Cordilleran冰盖有多广泛，而阿拉斯加东南部的任何地区都始终没有冰冰？该问题将使用先前提议的无冰区域的铍-10同位素基岩和巨石表面的宇宙基因曝光日期来解决。 再加上从公开的地形数据和航空影像中对古冰的详细映射，这些位置的接触年龄将使博士生可以重建西部山脉冰盖的最大程度。 （2）西部科迪勒冰盖的静修时间和速度是什么？ 沿海地区沿岩石表面的宇宙基因氏芽孢杆菌10将用于解决这个问题，这对海洋终止冰盖对气候变化的敏感性具有基本理解有影响。 （3）哪些环境因素（例如海洋变暖，大气变暖和海平面上升）影响了冰盖撤退？ 在这项研究中开发的撤退年表将与现有的气候和海平面记录相关，以检验以下假设：海洋变暖是影响阿拉斯加东南部海洋冰盖崩溃的主要因素。