COLLABORATIVE RESEARCH: Subglacial Till Genesis and Ice Sheet Dynamics, Lake Michigan Lobe Area, Illinois

通过详细的野外工作和模拟， 伊利诺伊州的沉积物记录将被调查，以确定 沉积在边缘地区的冰下冰碛物的起源 劳伦蒂德冰盖的最后一面 巨大的同质的双微粒 传统上被解释为直到五月才收房 主要起源于冰下变形， 变形床 密歇根湖叶剖面重建 在伊利诺伊州和初步的实地研究冰川沉积物， 这与已经提出的变形床的证据相一致 在理论上。 方法将包括两个夏天的详细 对精心挑选地点进行沉积学和结构研究， 专注于区分冰下冰碛物， 未变形的，直到经历了内部变形， 广泛的冰下剪切作用到大应变。 进一步分析 将包括：（1）地质技术分析，以评估 冰碛物的流变参数;（2）沉积物的测定 末次冰期盛期的输送通量， 将这些数据进行比较，将从不同模型中获得的数据 冰川搬运;（3）密歇根湖的数值模拟 叶片冰碛系统。 这项研究的结果将有 对解释大规模、 中纬度地区的同质耕作单位，以及 了解和模拟劳伦蒂德冰的动力学 床单。

By detailed field work and modeling, the late Quaternary sediment record in Illinois will be investigated to determine the origin of subglacial tills that were deposited in the marginal area of the Laurentide Ice Sheet. Massive, homogenous diamictons that classically have been interpreted to be lodgement till may instead have originated primarily through subglacial deformation in a deforming bed. Reconstructions of the Lake Michigan Lobe profile in Illinois and preliminary field study of glacigenic sediment are consistent with evidence of a deforming bed that has been suggested on theoretical grounds. Methods will consist of two summers of detailed sedimentological and structural study of carefully selected sites, focusing on differentiating subglacial till that is relatively undeformed from till that has experienced internal deformation by pervasive subglacial shearing to large strains. Further analysis will consist of: (1) geotechincal analyses in order to evaluate rheological parameters of the till; (2) determining sediment transport fluxes during the maximum of the last glaciation and comparing those data will data derived from different models of glacial transport; and (3) numerical modeling of the Lake Michigan Lobe ice-till system. The results of this research will have significant implications for interpreting the origin of massive, homogenous till units in mid-latitude regions, as well as for understanding and modeling the dynamics of the Laurentide Ice Sheet.