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

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

This project will evaluate uranium isotope ratios of clastic sediments as a measure of the time required for bedrock to be reduced to small grains by weathering, and then transported and deposited as sediment. The method may open up new ways of studying and understanding sediments, the processes that produce them, and how sedimentary processes are dependent on climate and tectonics. Detailed physical and chemical characterization of natural sediment from well-controlled environments will be combined with isotopic measurements. Fieldwork consists of collecting samples of terrestrial sediment from lakes, loess deposits, streams, and alluvial fans. The work is designed to further evaluate the approach and also investigate variations in sediment transport time as a function of climate and depositional environment. The combination of U-series isotopes and cosmogenic nuclides (Be-10 and Al-26) may yield information about timescales of soil generation, erosion, transport, and storage, and may allow important types of continental sedimentary deposits to be dated. Intellectual merit: The research will contribute to understanding of fundamental aspects of sedimentology and landscape evolution. The PI has 28 years experience in geochemical research, an extensive publication record, and has trained more than twenty Ph.D. students who have gone on to successful careers in academia, government, and private industry. U.C. Berkeley has a long record of support of advanced scientific research, and provides ample facilities, support personnel, and infrastructure for research and graduate education. Broader Impacts: The research has broad applicability to geology and environmental studies. It requires knowledge and training in mass spectrometry, analytical and nuclear chemistry, and hence is an excellent venue for advanced education. The funding will help support a research facility that, in the previous 15 years, has benefited 22 graduate students (10 women) 10 postdoctoral fellows (5 women), plus more than 20 visitors, undergraduates and collaborators.