Modeling Geomorphological and Cosmogenic-Nuclide Constraints on the Volume of the Quebec-Labradorean Sector of the Last Laurentide Ice Sheet

首席研究员将继续进行一项持续的、长期的、合作的研究，研究发生在劳伦泰德冰盖（LIS）东部沿海高地外围的高度可分离的不同风化的基岩表面的意义。该项目将侧重于1)利用地球宇宙成因核素和地貌数据确定基岩表面的暴露和埋藏历史；2)将这些数据与冰覆盖和冰流的地质证据结合起来，形成新的模型，以确定美国魁北克-拉布拉多兰地区的几何形状。重点将放在风化最严重的地区，这些地区在整个20世纪都集中在“努纳塔克争议”中。该项目有三个主要组成部分：1)通过测量暴露在宇宙辐射下的岩石中的10Be和26A1来获得时间限制；2)根据地质和地貌现场证据解释年代证据，以解决三个世纪以来的争议问题；3)利用对地表地质边界条件和沿东部边缘的垂直和横向限制敏感的正逆冰盖模型组合，建立新的地面真实几何。这项研究的结果将对当前和未来的地幔流变学研究产生直接影响，将为检验现有和广泛使用的冰盖模型的有效性提供一种机制，并将改进我们对海洋同位素记录的解释。一个真实的东大陆架模型，将有助于我们理解大陆架对北大西洋亚米兰科维奇气候和冰山漂流事件的影响。

The Principal Investigator will continue an ongoing, long-term, collaborative study of the significance of altitudinally separable differentially weathered bedrock surfaces that occur along the eastern coastal highland periphery of the Laurentide Ice Sheet (LIS). This project will focus on 1) determining the exposure and burial histories of bedrock surfaces, using terrestrial cosmogenic nuclides and geomorphic data; and 2) incorporating these data with geological evidence for ice cover and ice flow into new models for the geometry of the Quebec-Labradoran sector of the LIS. Emphasis will be placed on the most weathered terrains in regions that have focussed throughout the twentieth century in the 'nunatak controversy'.This project has three principal components: 1) obtaining chronological constraints by making measurements of 10Be and 26A1 in rock exposed to cosmic radiation; 2) interpreting chronological evidence in terms of the geological and geomorphological field evidence to address three century-old controversial questions; 3) developing a new ground-truthed geometry using a combination of forward and inverse ice sheet models that are sensitive to surface geological boundary conditions and vertical and lateral limits as pinned along the eastern margin.Results of this research will have direct implications on present and future studies of mantle rheology, will provide a mechanism to test the validity of existing and widely-used LIS ice sheet models, and will improve our interpretation of marine isotopic records. A ground-truthed model of the eastern LIS and will help our understanding of the LIS on sub-Milankovitch climate and iceberg rafting events in the north Atlantic.