Collaborative Research: The Pleistocene Erosion History of Glaciated Alpine Valleys Interrogated by Apatite 4He/3He Thermochronometry

这项研究将重建两个伟大的沿海中纬度山脉-不列颠哥伦比亚省的海岸山脉和新西兰的南阿尔卑斯山(菲奥德兰地区)内的侵蚀和地貌产生的详细历史。深而宽阔的高山峡谷是第四纪冰川最壮观的遗产之一。然而，关于这些山谷的侵蚀和起伏发展的总规模和时间和空间模式的具体信息很少。然而，这些山谷的侵蚀和起伏发展是形成主要山脉的侵蚀、气候和构造耦合系统演变的核心。在几百万年的时间尺度和不到2公里的挖掘厚度上获得关于这种山谷发育的定量信息，将是对解决晚新生代向冰川气候的转变是否伴随着山谷切割率增加和地貌产生增加的问题的重大贡献。这项研究将是一种非常有前途的新的地球化学工具--磷灰石4He/3He热年代学的首次系统应用。这项技术从根本上不同于传统的热计时方法，因为它对独特的低温很敏感，并且能够从单一矿物颗粒得出冷却历史。将检查结果与全球气候变化历史的联系，以及沿流域网络纵轴的特征变化模式。这项研究将确定一种新的地球化学技术的实用性，该技术有可能在地表过程研究和构造学中广泛应用。该项目将构成初级PI研究计划的重要组成部分，并将是他的新的惰性气体热计时实验室设施的首批科学应用之一。这项拟议的工作将构成研究生博士研究和培训的重要组成部分，并将作为本科课程的案例研究。

This research will reconstruct detailed histories of erosion and relief generation at locations within two great coastal mid-latitude mountain ranges, the Coast Mountains of British Columbia and the Southern Alps (Fiordlands region) of New Zealand. Deep and broadly scoured alpine valleys are one of the most spectacular legacies of Quaternary glaciation. However, very little specific information is available about the total magnitudes and the temporal and spatial patterns of erosion and relief development in these valleys. Yet erosion and relief development of these valleys is central to the evolution of the coupled system of erosion, climate, and tectonics that shapes major mountain ranges. Acquiring quantitative information about such valley development over timescales of a few million years and exhumation thicknesses of less than 2 km will be a major contribution toward resolving the question of whether the late Cenozoic transition to glacial climate was accompanied by increased valley incision rates and increased relief generation. This research will be the first systematic application of a very promising new geochemical tool, apatite 4He/3He thermochronometry. This technique is fundamentally different from conventional thermochronometric methods in its sensitivity to uniquely low temperatures and its ability to derive cooling histories from single mineral grains. Results will be examined for connections to the history of global climate change and for characteristic patterns of variation along the longitudinal axes of valley networks. The research will establish the usefulness of a new geochemical technique that has the potential for widespread applications in surface process studies and tectonics. The project will constitute an important part of the research program for a junior PI, and will be one of the first scientific applications of his new noble gas thermochronometry laboratory facility. The proposed work will constitute an important part of a graduate student's doctoral research and training, and will be used as a case study in undergraduate classes.