COSMOGENIC NUCLIDES APPROACH TO CONSTRAIN PALEO-EROSION RATES IN THE NORTHEWESTERN AMAZON.

• Grant number: 24/08072-5
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: August 26, 2024
• End date: August 25, 2025
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Fabiano do Nascimento Pupim
• Grantee: Caio Breda
• 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: 21/14947-6 - Paleogeographic reconstruction of northwestern Amazonian fluvial systems during the Pliocene and Quaternary, BP.DR

Abstract

The late Cenozoic (<23 Ma) is characterized by significant and well-documented environmental changes on all continents. During this period, the uplift of the Andes and climatic variations played a fundamental role in the evolution of the physical aspects of the Amazonia landscape, promoting its rich biodiversity. This doctorate project investigates the paleogeographic evolution of the Caquetá and Guaviare rivers, which are the main agents that molded the landscape of the northwestern Amazonia during the last 5 Ma. Our first results indicate that the Caquetá and Guaviare rivers, although geographically close (~300 km) but separated by the exhumation of the Vaupés Arch, were exposed to different climatic and tectonic conditions during the late Quaternary. These results were based on morphosedimentary maps, facies analysis, and luminescence dating, limiting our investigation to 150 ka. Thus, several open questions remain due to the lack of chronological data and the quantification of surface processes along the Quaternary and Pliocene. Thus, the aim of this Research Internships Abroad (BEPE) is to use in situ cosmogenic nuclides (10Be and 26Al) to (i) extend the age range of the sedimentary deposits up to the Pliocene and (ii) investigate how paleo-erosion erosion rates responded to tectonic and climate changes through time and space. The expected results will allow us to improve the understanding of the timing and mechanisms responsible for the landscape evolution of the Caquetá and Guaviare fluvial systems, in the northwestern Amazonia. Moreover, our results can shed new light on how past environmental changes affected the production (erosion) and transfer of sediments from mountains to foreland basins in tropical regions. The cosmogenic nuclide analyses will be carried out at the University of Potsdam, Germany, under the supervision of Dr. Bodo Bookhagen.