SGER: Terrestrial in situ Cosmogenic Nuclides (TCN), Grain Size, and the Processes of Erosion

知识优势：利用地球原位宇宙形成核素（TCN）已经成为一种量化地貌形成过程和计算侵蚀率的有力技术。冲积沉积物中的TCN浓度可能取决于所取样的冲积颗粒大小。这导致在计算正确的侵蚀速率方面存在问题，但在确定特定山坡和河道的风化和运输过程方面也存在未充分利用的潜力。本研究将利用TCN量化岩石向风土转化的山坡过程、风土向河道的搬运过程以及搬运过程中的粒度减小过程。考虑到这项技术正在被不同的地球科学家群体广泛接受，它既及时又有吸引力。华盛顿州西部的奥林匹克山脉和爱达荷州东部的莱姆希山脉是不同的，但以前研究得很充分的环境，用于探索变化的气候、构造和岩石类型对粒度- TCN浓度关系的影响。更广泛的影响：该研究将对如何估计冲积沉积物的全流域侵蚀速率，确定山坡侵蚀的过程、空间分布和速率，以及在长期景观演变数值模型中分配各种侵蚀过程具有直接和重要的意义。该研究结果将对奥运会研究区域的水道沉积物输送和流域生态系统管理产生重要影响，这些区域受到运动捕鱼、美洲原住民捕鱼和伐木的强烈使用压力。莱姆希山脉研究将转变为一个地质野外营地项目，这是一个开创性的尝试，将过程地貌学整合到夏季野外项目中，而夏季野外项目在很大程度上是构造-构造制图练习的领域。将支持博士候选人帕特里克·贝尔蒙特的学术培训。

Intellectual Merit: Use of terrestrial in situ cosmogenic nuclides (TCN) have emerged as a powerful technique to quantify landform-shaping processes and calculate rates of erosion. TCN concentrations in alluvial sediments can depend on the alluvial grain size sampled. This leads to problems in calculating the correct erosion rate, but also holds an underutilized potential for identifying specific hillslope and channel weathering and transport processes. This research will use TCN to quantify the hillslope processes of rock transformation into regolith, the transportation of the regolith to the channel, and grain size reduction during transport. It is both timely and attractive given that the technique is enjoying widespread acceptance by a diverse community of geoscientists. The Olympic Mountains of western Washington State and the Lemhi Range in eastern Idaho serve as diverse, but previously well-studied settings to explore the effects of variable climate, tectonics, and rock type on the grain size - TCN concentration relationship.Broader Impacts: The study will have immediate and important implications for how to estimate basin-wide erosion rates from alluvial sediment, identify the processes, spatial distribution, and rates of hillslope erosion, and apportion the various processes of erosion in numeric long term landscape evolution models. The results will have important implications for the delivery of sediment to channels and ecosystem management of the watersheds in the Olympics study area that have strong use pressures of sport fishing, Native American fish harvesting, and logging. The Lemhi Range study will be transformed into a geology field camp project which is a pioneering attempt to integrate process geomorphology into summer field programs that have largely been the domain of structure-tectonic mapping exercises. The academic training of a Ph.D. candidate, Patrick Belmont, will be supported.