Ice Sheet Configuration and Erosion Patterns in the Northern Swedish Mountains from Cosmogenic Radionuclides

瑞典北部山区的冰盖构造和宇宙放射性核素侵蚀模式

• 批准号: 9818162
• 负责人: Jonathan Harbor
• 金额: $ 17.82万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-15 至 2003-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9818162&HistoricalAwards=false
• 关键词: Ice; Sheet; Configuration; Erosion; Patterns

Unrealistic simulation of ice sheet inception and decay in mountainous regions, uncertainties in reconstructing ice surface profiles, and common failure to consider landscape development under ice sheets all contribute to major limitations for successful use of ice sheet models in climate research. For example, trimlines and weathering differences have been interpreted as indicators of former ice sheet height, but recent mapping in Scandinavia suggests that such features may reflect internal thermal boundaries between wet-(warm)-based erosive ice and dry-(cold) based-non-erosive ice, leading to very different interpretations of ice sheet thickness and height. The Principal Investigators will attempt to resolve conflicting glacial landform interpretations for parts of the Fennoscandian ice sheet. Geomorphologic and stratigraphic evidence indicates the Norwegian-Swedish mountains are an important area for understanding Fennoscandian ice sheet inception and decay. Glacial morphology in this mountain range reflects cirque glacier, valley glacier, and ice sheet erosion at different times and with various intensities over the past six million years. The oldest preserved surface is a potential reference horizon against which glacial erosion can be computed to enhance our understanding of ice sheet dynamics. This is critical groundwork for enhanced model simulations of the glacial cycle, which would test for general circulation models in predicting climate.This work will be accomplished by measuring multiple cosmogenic radionuclides in samples collected from rock surfaces in distinct, recently mapped, geomorphic regions. The results will test existing hypotheses of ice sheet configuration and provide new information for debates over the age of "preglacial" surfaces that appear to have survived repeated ice sheet overriding. The height of the Weichselian ice sheet and the spatial patterns of basal thermal regimes and associated glacial erosion of the Fennoscandian ice sheet will be studied. Insight into landscape development and basal thermal regimes will provide new boundary conditions for Fennoscandian ice sheet modeling being undertaken by Swedish scientists. The Principal Investigators will field test whether a surface has experienced lengthy ice burial with a new application of cosmogenic radionuclides. To be successful, the Principal Investigators will collect samples from sites within landscapes of different types of glacial histories. The Swedish Natural Science Research Council has funded the Principal Investigators' Swedish counterparts for similar work and the two groups will work collaboratively on this project. Recognition of suitable landscape features relies on high quality mapping of mountain geomorphology which is a primary area of expertise of the Paleoglaciology Group at the University of Stockholm. Purdue University facility and facilities will provide expertise and analytical capabilities in glacial geomorphology and applications of cosmogenic radionuclide techniques.

不切实际的模拟冰盖的开始和衰减在山区，不确定性在重建冰表面的轮廓，并普遍未能考虑冰盖下的景观发展，都有助于在气候研究中成功使用冰盖模式的主要限制。 例如，纵倾线和风化差异被解释为前冰盖高度的指标，但最近在斯堪的纳维亚半岛的测绘表明，这些特征可能反映了湿（暖）基侵蚀性冰和干（冷）基非侵蚀性冰之间的内部热边界，导致对冰盖厚度和高度的非常不同的解释。 主要研究人员将试图解决芬诺斯坎迪亚冰盖部分地区相互矛盾的冰川地貌解释。 地貌和地层学证据表明，挪威-瑞典山脉是了解芬诺斯堪的纳维亚冰盖形成和衰退的重要地区。 这条山脉的冰川形态反映了过去600万年来不同时间和不同强度的冰斗冰川、山谷冰川和冰盖侵蚀。 最古老的保存表面是一个潜在的参考地平线上的冰川侵蚀可以计算，以提高我们对冰盖动力学的理解。 这是加强冰川循环模型模拟的关键基础，将测试大气环流模型预测气候，这项工作将通过测量从最近绘制的不同地貌区域的岩石表面收集的样品中的多种宇宙成因放射性核素来完成。 这些结果将检验现有的冰盖构造假设，并为关于“冰前”表面年龄的辩论提供新的信息，这些表面似乎在冰盖的反复覆盖下幸存下来。 将研究Weichselian冰盖的高度和Fennoscandian冰盖的基本热制度和相关的冰川侵蚀的空间格局。 深入了解景观的发展和基础热制度将提供新的边界条件Fennoscandian冰盖建模正在进行的瑞典科学家。 主要研究人员将实地测试一个表面是否经历了漫长的冰埋与宇宙成因放射性核素的新应用。为了取得成功，主要研究人员将从不同类型的冰川历史景观中收集样本。 瑞典自然科学研究理事会为主要研究者的瑞典同行进行类似工作提供了资金，两个小组将在该项目上合作。 识别合适的地貌特征有赖于高质量的山区地貌制图，这是斯德哥尔摩大学古冰川学小组的主要专门知识领域。 普渡大学的设施将提供冰川地貌学和宇宙成因放射性核素技术应用方面的专门知识和分析能力。