Cosmogenic Nuclide Chronology of Weathering Zones and Ice Sheet Limits in Northern Labrador: A Pilot Study

该提案要求为一项试点研究提供资金，该研究将宇宙形成核素暴露年龄应用于拉布拉多北部托恩加特山脉的冰川沉积物，这些沉积物是由劳伦泰德冰盖东部边缘沉积的。这一冰碛和漂流序列代表了至少两个连续的托恩加特山脉有限冰期，是研究北美风化带的“类型区”。尽管经过了一个多世纪的研究，这个经典的不同风化的冰川沉积物序列的年代学仍然非常不确定。此外，该地区的冰川史是重建Laurentide冰盖过去历史的关键组成部分，Laurentide冰盖对末次冰期全球气候产生了重大影响。将收集用于测量宇宙成因10Be和其他宇宙成因核素的样品，以评估该地区进行暴露测年研究的适用性。初步的10Be数据将用于创建该地区的绝对暴露年龄年表，并评估先前绘制的矿床和相关矿床的相关性。提出的工作及其可能的扩展的潜在结果包括：在一个地区的一个大部分未定年的冰川序列的绝对年代学，这对于重建末次盛冰期（LGM）劳伦泰德冰盖的边缘至关重要。与lgm前larentide冰盖推进相关的冰川沉积物和冰盖限制的年龄限制。亚北极/北极地区岩石表面侵蚀速率和风化历史的制约因素。

This proposal requests funds for a pilot study applying cosmogenic nuclide exposure ages to glacial deposits in the Torngat Mountains, northern Labrador, that were deposited by the eastern margin of the Laurentide Ice Sheet. This sequence of moraines and drift represents at least two successively limited glaciations of the Torngat Mountains and is a "type area" for study of weathering zones in North America. Despite over a century of study, the chronology of this classic sequence of differentially weathered glacial deposits is highly uncertain. Furthermore, the glacial history of this region is a key component in reconstructing the past history of the Laurentide Ice Sheet, which exerted a major influence on global climate during the last glacial period. Samples for measurement of cosmogenic 10Be and other cosmogenic nuclides will be collected to evaluate the suitability of this region for exposure dating studies. The preliminary 10Be data will be used to create an absolute exposure age chronology for the region, and to evaluate the correlation of previously mapped and correlated deposits. Potential results of the proposed work and its possible extensions include: An absolute chronology for a largely undated glacial sequence in an area that is crucial for reconstructing the margins of the Laurentide Ice Sheet at the last glacial maximum (LGM). Age constraints for glacial deposits and ice sheet limits related to pre-LGM Laurentide Ice Sheet advances in Labrador. Constraints on erosion rates and weathering history of rock surfaces in sub-Arctic/Arctic regions.