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Paleoerosion rates and sediment flux along the Amazon fluvial system in response to Andean tectonism and regional climate regimes during the late Neogene and Pleistocene

Grant number: 23/16031-4
Support Opportunities:Scholarships in Brazil - Doctorate
Effective date (Start): February 01, 2024
Effective date (End): January 31, 2027
Field of knowledge:Physical Sciences and Mathematics - Geosciences - Geology
Principal Investigator:Fabiano do Nascimento Pupim
Grantee:Carolina Barbosa Leite da Cruz
Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:22/03007-5 - From sand grains to mountain chains: linking recent Andean orogenesis and climate changes to the assembly of lowland Amazonia (PAALE), AP.PNGP.PI

Abstract

The effect of late Cenozoic climate changes and mountain building events on sediment flux derived from the eastern Andes has a critical role for terrestrial and aquatic ecosystems because it shapes the distribution of non-flooding (terra firme) and seasonally flooding (várzea and igapó) areas in lowland Amazonia, and controls the supply of nutrients to freshwater and marine ecosystems. The existing thermochronological and paleo-altimetry datasets suggest that the Andean surface uplift and long-term erosion rates were spatially and temporally variable from the Oligocene to Miocene. However, the uplift and erosion rates from the late Miocene to the Late Pleistocene remain elusive due to poor sedimentary records and the fact that the available thermochronological techniques do not allow resolving erosion rates at the millennial timescale. Thus, missing essential time windows of landscape and biotic change. Terrestrial (in situ) cosmogenic nuclides (TCN) have been shown to be a robust metric for recovering erosion rates that integrate the millennial timescale. Here, we will (i) investigate the effects of the Andean tectonism and regional climate changes on paleoerosion rates and sediment provenance from the eastern Andes to its foreland basins in Amazonia during the late Neogene and Pleistocene, and (ii) assess how these erosion and provenance signals propagate along with the Amazon fluvial system, since the Andes until the river mouth. Therefore, we will use TCN and luminescence techniques to: (1) determine the burial ages of sediment deposits since 5 Ma; (2) constraining paleoerosion rates and sediment provenance in well-dated deposits (up to 10 Ma) to estimate Andean erosion rates and Amazonian lowland sediment input and propagation through time and space; (3) confronting the spatiotemporal erosional histories with prior data on Andean uplift and long-term climatic shifts to interpreting possible causal mechanisms of landscape changes in the Amazonian lowlands.

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