Collaborative Research: Probing the Role of Rock Type in the Evolution of Glacial Landscapes

该项目将调查岩石类型对冰川侵蚀的作用。虽然了解了冰川侵蚀的过程，但这项研究的意义在于解决岩石类型和岩体破裂程度对侵蚀速度和模式的控制。侵蚀速率控制着泥沙向河流和海洋的输送，而侵蚀模式决定了被冰川侵蚀的山脉的地形结构和高度。在阿拉斯加山脉壮观的基恰特纳山脉和德纳利地块的花岗岩核和变质围岩中暴露的对比岩石类型的侵蚀速率将使用三种尖端方法来完成：冰川顶壁和侧壁剖面中的磷灰石中的4He/3He，现代崩塌和内侧冰雹中的宇宙成因放射性核素浓度，以及出口溪流沉积物中的ND。现代和十年尺度的冰川速度将使用GPS和对存档的航空照片进行分析来记录。结果将使用冰川、冰川侵蚀的山谷和剩余岩石内不断演变的热场的数值模型来综合。布罗德影响虽然长期以来人们已经认识到岩石类型应该通过各种地貌过程影响侵蚀速度，但这项研究在关注岩石类型的作用方面将是新颖的，并应突出目前可用于解决这些问题的工具包。这项研究将是一名博士生的重点，并将为初级PI正在开发的新的4He/3He方法提供另一个试验台。这项研究的成果将被纳入大学课程，以及在大学和公共场所的公开演讲中，包括国家公园，在这些公园里，冰川过程占据主导地位，形成了供公众重现的景观。

This project will investigate the role of rock type on glacial erosion. While the processes of glacial erosion are understood, the significance of this research lies in addressing the control of both the type of rock and the degree of fracturing of the rock mass on the rates and patterns of erosion. Erosion rates control sediment delivery to rivers and oceans, while erosion patterns dictate both the topographic architecture and the heights of mountain ranges being attacked by glaciers. Determination of erosion rates in contrasting rock types, exposed in the granitic cores and metamorphic country rocks of the spectacular Kichatna Range and Denali Massif of the Alaska Range, will be accomplished using three cutting-edge methods: 4He/3He in apatites from glacial headwall and sidewall profiles, cosmogenic radionuclide concentrations in modern rockfall and medial moraines, and Nd in the sediments of outlet streams. Modern and decadal scale glacial speeds will be documented using GPS and analysis of archived air photographs. The results will be synthesized using numerical models of the glaciers, the valleys they erode, and the evolving thermal field within the remaining rock.Broader impactsWhile it has long been acknowledged that rock type should influence the rates of erosion by a variety of geomorphic processes, this research will be novel in its focus on the role of rock type, and should highlight the toolkit now available to address such issues. The research will be the focus of one PhD student, and will provide another testbed for the new 4He/3He method being developed by the junior PI. The results of the research will be incorporated in college courses, and in public talks at both university and public venues, including national parks in which glacial processes have dominated in the producing the landscapes in which the public recreates.