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

• Grant number: 25/08240-8
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: August 01, 2025
• End date: January 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Dailson José Bertassoli Junior
• Grantee: Lara Poliny Nogueira da Silva
• Supervisor: Alfredo Martinez Garcia
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Max Planck Society, Mainz, Germany
• Associated to the scholarship: 24/00766-8 - A multiproxy approach to reconstruct hydrological changes in Eastern Amazonia during the late Holocene;, BP.MS

Abstract

The Amazon Basin, has become an increasingly important focus for paleoclimate reconstructions aimed at improving our understanding of long-term climate variability and its relevance to ongoing climate change. Organic molecular proxies have proven to be valuable tools for retrieving information about past climate oscillations. Among the various terrestrial climate archives, speleothems stand out due to their capacity to provide insights into past precipitation, temperature, and their potential for establishing robust chronological frameworks. In the Amazon Basin, speleothem-based studies using ¿18O isotopic records have significantly advanced our understanding of past hydroclimate variability. These studies have been particularly instrumental in deciphering the dynamics of the South American Monsoon System (SAMS) and identifying persistent east-west climate dipole patterns. However, despite the recognized potential of organic geochemical techniques, comprehensive reconstructions of paleotemperature using molecular organic proxies remain scarce in the region. This study aims to reconstruct Holocene paleotemperatures in the Amazon Basin through the analysis of organic compounds from speleothem records. We will employ the TEX86 index, a well-established organic molecular indicator of past temperatures, to generate new and independent paleotemperature reconstructions. The resulting data will be integrated with existing datasets from bibliography, and from sediment cores that we also collected in previous sample campaign, to enhance our understanding of atmospheric and hydrological conditions during the Holocene. This research will be conducted at the Max Planck Institute for Chemistry (MPIC), Germany, in collaboration with Dr. Martinez-Garcia that is a leading expert in the development and application of a wide range of geochemical techniques, including the use of organic biomarkers and stable isotopes (H, C, N, O). The integration of these methods is expected to yield more comprehensive and reliable paleoclimate reconstructions for the Amazon Basin.