Terrestrial cosmogenic nuclides analysis to reconstruct changes in the Amazonian fluvial system in the late Cenozoic (<5 ma)

Abstract

The Amazon basin is the largest in the world and cradle to one of the most biodiverse ecosystems on Earth. Biogeographical studies have suggested that the evolution of the Amazonian river system played a critical role for species diversification. The main hypotheses suggest that modern Amazonian river system acquired its transcontinental W-E configuration during the Late Neogene due to changes in Andean tectonics. Nonetheless, there is no consensus as to the timing formation of the lowland Amazonia (from 11 to 2.5 Ma ago). This knowledge gap results from the lack of absolute ages for the Late Neogene and Quaternary fluvial sediments, and absence of proxies suitable for comparisons between ancient and modern fluvial system. Thus, this internship project aims to use cosmogenic nuclides (26Al and 10Be) to determine the age and paleo-erosion rates of Late Neogene (~5 Ma) fluvial sediments from Amazonia. It will be used to reconstruct the evolution of the major Amazonian rivers through space and time. Such a record will provide insight into the response of the Amazonian rivers to climate, sea level, and tectonic changes. Such records would be used to shed light on the challenging problems concerning how Amazonia developed its high biodiversity and current biogeographic provinces, and inform models that will be used to predict the future changes in the Amazonian ecosystem. The internship will be developed at the Imperial College London (UK), supervised by Dr. Dylan Rood. The motivation for this internship is learning (continued training) of analytical procedures, data analysis and interpretation of cosmogenic nuclides applied to dating of sedimentary deposits and quantification of erosion rates. (AU)