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

这项提议要求为一项试点研究提供资金，将宇宙成因核素暴露年龄应用于拉布拉多北部Torngat山脉的冰川沉积物，这些沉积物是由Laurentide冰盖东缘沉积的。这一冰雹和漂移序列代表了托恩加特山脉至少两个连续的有限冰川，是研究北美风化带的典型地区。尽管经过了一个多世纪的研究，但这一典型的不同风化冰川沉积序列的年代学仍然非常不确定。此外，该地区的冰川历史是重建劳伦蒂冰盖过去历史的关键组成部分，劳伦蒂冰盖在上一次冰川时期对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，以评估该区域是否适合进行暴露测年研究。初步的10Be数据将被用来创建该地区的绝对暴露年龄年表，并评估以前绘制的地图和相关矿床的相关性。这项拟议工作及其可能扩展的潜在结果包括：一个地区的大部分未确定日期的冰川序列的绝对年代学，该地区对于重建最后一次冰川盛期(LGM)的劳伦蒂德冰盖边缘至关重要。冰川沉积的年龄限制和与拉布拉多LGM前Laurentide冰盖进展有关的冰盖限制。对亚北极/北极地区岩石表面侵蚀速度和风化历史的限制。

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.