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

这个项目将研究岩石类型对冰川侵蚀的作用。在了解冰川侵蚀过程的同时，本研究的意义在于解决岩石类型和岩体破碎程度对侵蚀速率和模式的控制问题。侵蚀速率控制着沉积物向河流和海洋的输送，而侵蚀模式决定了地形结构和受到冰川侵蚀的山脉的高度。在阿拉斯加山脉壮观的基查特纳山脉和迪纳利山脉的花岗岩岩心和变质岩石中，对比岩石类型的侵蚀速率的测定将使用三种前沿方法来完成：冰川顶壁和侧壁剖面中磷灰石中的4He/3He，现代岩崩和中部冰碛中的宇宙成因放射性核素浓度，以及出口河流沉积物中的Nd。现代和年代际尺度的冰川速度将利用GPS和对存档的航空照片的分析进行记录。研究结果将利用冰川、它们所侵蚀的山谷以及剩余岩石中不断演变的热场的数值模型进行综合。更广泛的影响虽然人们早就认识到岩石类型应该通过各种地貌过程影响侵蚀速率，但这项研究将是新颖的，因为它关注岩石类型的作用，并且应该突出现在可用的工具包来解决这些问题。该研究将成为一名博士生的研究重点，并将为初级PI正在开发的新的4He/3He方法提供另一个测试平台。研究结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，包括冰川过程主导的国家公园，在这些公园中，公众可以在其中休闲娱乐。

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.