International Research Fellowship Program: Determining Bedrock Incision Rates using Cosmogenic Isotope \3He\ Analysis to Chronologically Constrain the Wetland Development Cycle in

Keen-Zebert Amanda K, Fayetteville AR

Investigators

Abstract

0754345 Keen-Zebert The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four month research fellowship by Dr. Amanda Keen-Zebert to work with Dr. Stephen Tooth at the University of Wales, Aberystwyth in the UK. Wetlands are a focus of conservation efforts worldwide. However, geomorphological wetland research has been limited. In the Highveld of South Africa, the relationship between alluvial and bedrock river processes has consequences on the stability of wetlands that are an important water resource in a subhumid to semiarid area. The researchers in this project are investigating the long term development and sedimentological factors that effect wetland development and stability in South Africa. The researchers are adding a chronological element to a conceptual model of wetland development in the region that suggests that the progression from exhumation to breeching of dolerite intrusions into less resistant sedimentary rock controls the cycle of wetland development. By determining the bedrock incision rates through the dolerite intrusions using cosmogenic isotope analysis (CIA) and the timing of floodplain development through optically stimulated luminescence (OSL), it is possible to add long term chronological constraint to the conceptual model of wetland development. The improvement of the model will increase the understanding of river development in southern Africa, as well as the understanding of alluvial bedrock rivers and the interaction between alluvial and bedrock processes. Current wetland rehabilitation efforts in southern Africa are directed at human causes of degradation. If the degradation of these wetlands is structurally geomorphic in nature, then management strategies need adjustment. The information gained in this study will benefit wetland conservation and rehabilitation programs in South Africa.