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

智慧的优点：使用陆地原位宇宙成因核素(TCN)已成为量化地形形成过程和计算侵蚀速率的一种强有力的技术。冲积沉积物中TCN的浓度可能取决于取样的冲积颗粒大小。这导致在计算正确的侵蚀速率时出现问题，但在识别特定的山坡和河道风化和输送过程方面也具有未得到充分利用的潜力。这项研究将利用TCN来量化岩石转化为风化层的山坡过程、风化层向渠道的输送以及颗粒在运输过程中的减小。考虑到这项技术正在被不同的地球科学家社区广泛接受，这既是及时的，也是有吸引力的。华盛顿州西部的奥林匹克山脉和爱达荷州东部的Lemhi山脉是多样化的，但之前已经很好地研究了气候、构造和岩石类型变化对粒度-TCN浓度关系的影响。广泛影响：这项研究将对如何从冲积沉积物估计盆地范围的侵蚀速率，确定坡面侵蚀的过程、空间分布和速率，以及在数字长期景观演化模型中分配各种侵蚀过程具有直接和重要的意义。研究结果将对奥林匹克研究区的河流泥沙输送和流域的生态系统管理具有重要意义，这些流域有很大的使用压力，如休闲捕鱼、美洲原住民捕鱼和伐木。Lemhi山脉研究将转变为地质野外营地项目，这是将过程地貌学整合到夏季野外项目中的一次开创性尝试，夏季野外项目在很大程度上一直是构造-构造制图工作的领域。对博士生帕特里克·贝尔蒙特的学术培训将得到支持。

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.