A multiproxy approach to reconstruct hydrological changes in Eastern Amazonia during the late Holocene;

• Grant number: 24/00766-8
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2024
• End date: February 28, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Dailson José Bertassoli Junior
• Grantee: Lara Poliny Nogueira da Silva
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/06440-1 - Wetland expansion in Amazonia during the late Holocene and its implications to the global methane budget, AP.GR

Abstract

Deciphering hydroclimatic imbalances in the Lower Amazon River Basin is challenging. Speleothem records show a consistent increase in precipitation over western Amazonia from the mid- to late Holocene, but other parts of the basin appear to have responded differently. Previous literature has regarded the contrasting difference in Amazonian precipitation as a dipole response to orbital-scale insolation variability. However, variations in eastern Amazonian speleothem records seem to be weakly correlated with precession cycles. To reconstruct regional hydroclimate variability in eastern Amazonia, we will investigate two sediment cores collected from the Tapajós Ria. We propose analyzing the hydrogen and stable carbon isotope compositions of long-chain n-alkanes to infer changes in paleoprecipitation and vegetation. Additionally, we will use major element distributions, luminescence sensitivity signals, and neodymium isotopes to reconstruct changes in the relative influx of Amazon River sediments into the Tapajós Ria.