Transport times and ages of Quaternary fine-grained terrestrial sediments using U series isotopes

该项目将评估碎屑沉积物的铀同位素比值，以衡量基岩被风化还原为细小颗粒所需的时间，并作为沉积物运输和沉积。这种方法可能会为研究和理解沉积物、产生沉积物的过程以及沉积过程如何依赖气候和构造开辟新的途径。将结合同位素测量对控制良好的环境中的自然沉积物进行详细的物理和化学特征分析。野外工作包括从湖泊、黄土沉积物、溪流和冲积扇中收集陆地沉积物样本。这项工作旨在进一步评估该方法，并调查泥沙运移时间随气候和沉积环境的变化。铀系列同位素和宇宙成因核素(Be-10和Al-26)的组合可以提供有关土壤生成、侵蚀、运移和储存的时间尺度的信息，并可能使重要类型的大陆沉积矿床获得年代。学术价值：这项研究将有助于理解沉积学和地貌演化的基本方面。该协会在地球化学研究方面有28年的经验，有广泛的出版记录，并培养了20多名博士生，他们后来在学术界、政府和私营行业取得了成功。加州大学伯克利分校长期支持高级科学研究，并为研究和研究生教育提供充足的设施、支持人员和基础设施。更广泛的影响：这项研究对地质学和环境研究具有广泛的适用性。它需要在质谱学、分析和核化学方面的知识和培训，因此是一个很好的进修场所。这笔资金将帮助支持一个研究设施，在过去15年中，该设施使22名研究生(10名女性)、10名博士后研究员(5名女性)以及20多名来访者、本科生和合作者受益。

This project will evaluate uranium isotope ratios of clastic sediments as a measure of thetime required for bedrock to be reduced to small grains by weathering, and thentransported and deposited as sediment. The method may open up new ways of studying andunderstanding sediments, the processes that produce them, and how sedimentary processesare dependent on climate and tectonics. Detailed physical and chemical characterizationof natural sediment from well-controlled environments will be combined with isotopicmeasurements. Fieldwork consists of collecting samples of terrestrial sediment fromlakes, loess deposits, streams, and alluvial fans. The work is designed to furtherevaluate the approach and also investigate variations in sediment transport time as afunction of climate and depositional environment. The combination of U-series isotopesand cosmogenic nuclides (Be-10 and Al-26) may yield information about timescales of soilgeneration, erosion, transport, and storage, and may allow important types of continentalsedimentary deposits to be dated. Intellectual merit: The research will contribute tounderstanding of fundamental aspects of sedimentology and landscape evolution. The PI has28 years experience in geochemical research, an extensive publication record, and hastrained more than twenty Ph.D. students who have gone on to successful careers inacademia, government, and private industry. U.C. Berkeley has a long record of support ofadvanced scientific research, and provides ample facilities, support personnel, andinfrastructure for research and graduate education. Broader Impacts: The research hasbroad applicability to geology and environmental studies. It requires knowledge andtraining in mass spectrometry, analytical and nuclear chemistry, and hence is an excellentvenue for advanced education. The funding will help support a research facility that, inthe previous 15 years, has benefited 22 graduate students (10 women) 10 postdoctoralfellows (5 women), plus more than 20 visitors, undergraduates and collaborators.