COLLABORATIVE RESEARCH: Cosmogenic Nuclide Chronology of Bedrock Weathering Zones in Fennoscandia and Implications for the History of the Fennoscandian Ice Sheet

合作研究：芬诺斯坎迪亚基岩风化带的宇宙成因核素年代学及其对芬诺斯坎迪亚冰盖历史的影响

• 批准号: 9726185
• 负责人: Scott Lehman
• 金额: $ 5.01万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9726185&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Cosmogenic; Nuclide; Chronology

9726185 Lehman The goal of the proposed work is to constrain models of the Fennoscandian ice sheet (FIS) during the last glacial maximum (LGM) and subsequent deglaciation by applying techniques of surface exposure chronology using cosmogenic nuclides. A large body of field work in the high mountains of Norway documents high altitude glacial trimlines and areas of deeply weathered bedrock that have a regionally consistent configuration, suggesting that they may demark the vertical limit of the FIS. However, profiles based on the spatial distribution of these features differ significantly from profiles of ice sheet elevation derived from various numerical and conceptual ice sheet reconstructions (for example, ICE-4G and CLIMAP). Although it is clear that one of the two general approaches to reconstructing the FIS is flawed, it is difficult to say which one, primarily because the geomorphic features under debate have not been dated. Our prior work in the mountains of western Norway demonstrate that such dating is, indeed, feasible. The proposed work will produce the first numerical chronology for these features, thereby permitting us to assess the validity of various ice sheet reconstructions for the region, and, by inference, in North America (e.g. for the Laurentide ice sheet). As the CLIMAP and ICE-4G reconstructions have been widely adopted as boundary conditions in simulations of LGM climate using atmospheric general circulation models, our studies will also bear on the efficacy of those modeling results and related assessments of climate sensitivity. In addition, the proposed work will address a fundamental problem in glacial geology that of interpretation of weathering zones in formerly glaciated regions of the Northern Hemisphere.

小行星9726185 拟议的工作的目标是约束模型的芬诺斯堪的纳维亚冰盖（FIS）在末次冰期最大（LGM）和随后的冰川消退应用技术的表面暴露年代学使用宇宙成因核素。 在挪威高山的大量实地工作记录了高海拔冰川纵倾线和具有区域一致配置的深度风化基岩区域，这表明它们可能区分FIS的垂直界限。 然而，这些功能的空间分布的基础上的配置文件显着不同的配置文件的冰盖海拔来自各种数值和概念冰盖重建（例如，ICE-4G和CLIMAP）。 虽然很明显，重建FIS的两种一般方法之一是有缺陷的，但很难说是哪一种，主要是因为争论中的地貌特征尚未确定日期。 我们先前在挪威西部山区的工作表明，这种测年法确实可行。 拟议中的工作将产生这些功能的第一个数字年表，从而使我们能够评估该地区的各种冰盖重建的有效性，并通过推理，在北美（例如，Laurentide冰盖）。 由于CLIMAP和ICE-4G重建已被广泛采用作为边界条件，在使用大气环流模式模拟LGM气候，我们的研究也将承担这些模拟结果的有效性和气候敏感性的相关评估。 此外，拟议的工作将解决冰川地质学中的一个基本问题，即解释北方半球以前的冰川地区的风化带。