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

9726185雷曼，拟议工作的目标是通过应用使用宇宙成因核素的地表暴露年代学技术，限制芬诺斯坎迪亚冰盖在最后一次冰盛期(LGM)和随后的冰川消融期间的模型。挪威高山上的大量野外工作记录了高海拔冰川修剪线和深度风化基岩区域，这些区域具有地区一致的配置，这表明它们可能标志着FIS的垂直界限。然而，基于这些特征的空间分布的剖面与由各种数值和概念性冰盖重建(例如ICE-4G和CLIMAP)得出的冰盖高度剖面有很大的不同。虽然重建金融信息系统的两种一般方法中的一种显然是有缺陷的，但很难说是哪一种，主要是因为辩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，这种测年确实是可行的。拟议的工作将为这些特征产生第一个数字年表，从而使我们能够评估该区域各种冰盖重建的有效性，并由此推断，在北美(例如，洛伦蒂冰盖)。由于CLIMAP和ICE-4G重建已经被广泛地用作大气环流模式模拟末次盛冰期气候的边界条件，我们的研究也将涉及到这些模拟结果的有效性和相关的气候敏感性评估。此外，拟议的工作将解决冰川地质学中的一个基本问题，即北半球以前冰川地区的风化带的解释。

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.