RII Track-4: Using Novel Applications of Luminescence Techniques to Evaluate Channel Mobility and Bedrock Valley Development

Kansas State University, Manhattan KS

Investigators

Abstract

Nontechnical Description By eroding and depositing sediment, river systems record past changes in climate, hydrology, vegetation, and tectonic processes on the Earth's surface. While vertical erosion into bedrock landscapes has been extensively studied, there is little consensus on how rivers erode laterally in bedrock landscapes. It is crucial to establish the duration of lateral widening intervals that create bedrock valleys in order to understand how changes in river dynamics shape the Earth's surface. Through a collaboration with the Desert Research Institute (DRI), the PI will learn luminescence dating techniques that will allow her to establish the timing of lateral erosion intervals and apply these techniques to infer transport history of sediments. Determining the timing of past and current river incision is important for predicting the effect of ongoing landscape change on humans who live and work near rivers in Kansas, the PI's home state. The PI's home institution, Kansas State University, will benefit from the professional development of the PI, her extended collaborative network with DRI, and the incorporation of dating techniques in research and teaching to demonstrate how local rivers change on decadal and centennial time scales that humans must be prepared to adapt to. Technical Description The processes that control vertical incision in bedrock rivers are widely studied and well characterized; however, the fundamental processes that control lateral erosion have not been quantified in the laboratory or in the field. Field data that describes past channel mobility and defines absolute time constraints on the length of lateral erosion intervals are vital for better understanding the conditions that result in wide bedrock valleys. Analysis of luminescence properties is a key tool for dating fluvial deposits to determine periods of lateral erosion and vertical incision. It also has the potential to illuminate transport processes, such as channel mobility, during periods of sediment deposition. Research conducted during this project has the potential to transform our understanding about the processes and timing of the evolution of bedrock valley systems. Two main project objectives support the overarching goals: (1) learning single-grain luminescence techniques to date the depositional age of sediments with complex transport histories; (2) interpreting luminescence properties as a proxy for fluvial processes, such as channel mobility. Using luminescence techniques to interpret geomorphic processes is an emerging application that has the potential to give insight beyond dating. When this project is complete, the geomorphology community will be closer to interpreting luminescence properties as proxies of transport processes to assess past channel mobility from sediment deposited in association with periods of bedrock valley formation and ultimately a new way of interpreting a wealth of measured, but previously unexamined data. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.