Determining late Quaternary variations in paleoerosion rates across the Amazon River basin using cosmogenic nuclides in fluvial sediments

• Grant number: 25/11996-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: January 10, 2026
• End date: January 09, 2027
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Fabiano do Nascimento Pupim
• Grantee: Anarda Luísa Sousa Simões
• Supervisor: Bodo Bookhagen
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University of Potsdam, Germany
• Associated to the scholarship: 23/16001-8 - The erosion and sediment flux response to late Quaternary hydroclimate change quantified using in situ cosmogenic nuclides and optically stimulated luminescence., BP.DR

Abstract

Late Quaternary hydroclimate changes, mainly in precipitation and river discharge, played an important role in the spatial and temporal development of the Amazonian lowlands. Detailed mechanisms behind these changes and how they shaped the landscape are still unclear, however they are fundamental to understanding the spatial distribution and evolutionary processes of the most diverse biota on the planet. In this context, we have proposed a doctoral project (FAPESP 2023/16001-8) to investigate the effects of the Late Quaternary hydroclimate changes in palaeo-erosion rates and sediment provenance from the eastern Andes to the Amazonian lowlands, coupling luminescence dating to erosion rates derived from terrestrial cosmogenic nuclides (TCN). Our first results indicate that at least three levels of fluvial terraces were formed and preserved during the late Quaternary in the upper (Juanjui region) and central (Iquitos and Coari region) Amazon River Basin, with optically stimulated luminescence ages that vary from 100 ka to the present. Moreover, a new sediment core collected near the mouth of the Amazon River preserves continuous sediments along the late Quaternary (<120 ka). Based on these sedimentary archives and OSL ages, this BEPE proposal will use 26Al and 10Be cosmogenic nuclides to reconstruct palaeo-erosion rates across time (late Quaternary) and space (source to sink) in the Amazon River Basin. The combination of OSL ages and cosmogenic nuclides derived paleo-erosion rates will allow us to test (i) whether variations in erosion rate may be correlated to past climate and (ii) if the transfer of sediments from source to sink is continuous or if part of the sediments are recycled during sediment routing. We expect to improve the understanding of the timing and mechanisms responsible for the landscape evolution of the Amazon fluvial system, providing insights on how past environmental changes affected the production (erosion) and transfer of sediments from mountains to foreland basins in tropical regions. This BEPE project will be developed at the University of Potsdam, Germany, under the supervision of Dr. Bodo Bookhagen.