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

合作研究：冰下冰床成因和冰盖动力学，伊利诺伊州密歇根湖波瓣地区

• 批准号: 9204838
• 负责人: W. Johnson
• 金额: $ 8.12万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-07-01 至 1995-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9204838&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Subglacial; Till; Genesis

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.

通过详细的现场工作和建模，将研究伊利诺伊州的晚期沉积物记录，以确定沉积在Laurentide冰盖边际区域的冰川耕种的起源。 从经典上解释为直到可能的庞大的同质脉传，直到可能是主要是通过变形床中的冰下变形来起源的。 伊利诺伊州密歇根湖叶轮廓的重建以及冰原沉积物的初步现场研究与理论上建议的变形床的证据一致。 方法将包括两个详细的沉积学和结构研究的夏季，重点是区分冰山，直到与直到直到那样，这已经通过普遍的亚冰块剪切到大型菌株经历了内部变形。 进一步的分析将包括：（1）岩土分析以评估till的流变参数； （2）确定最后一次冰川期间的沉积物传输通量并比较这些数据将从不同的冰川传输模型得出的数据； （3）密歇根湖叶冰结系统的数值建模。 这项研究的结果将对解释中纬度区域的大规模，同质直至单位的起源以及理解和建模劳伦德郡冰盖的动力学有重要意义。