Quartz luminescence sensitization in brazilian biomes and its application in Cenozoic Amazonian terrestrial surface process reconstruction

• Grant number: 24/00916-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: July 01, 2024
• End date: July 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: André Oliveira Sawakuchi
• Grantee: William Mozart Henrichs
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 18/23899-2 - Trans-Amazon Drilling Project: origin and evolution of the forests, climate, and hydrology of the South American tropics, AP.PFPMCG.TEM

Abstract

The goal of the project is to examine how thermoluminescence (TL) and optically stimulated luminescence (OSL) can be applied to evaluate the natural sensitization processes of quartz in sedimentary systems and soils. With their relationship to thermal events (like burning) and solar exposure (like sediment transport and bioturbation), the TL (peak at 110 ºC) and OSL (fast component) sensitivities of quartz have become more and more used in sediment provenance studies. This opens the door to the development of proxies of terrestrial surface processes applied to the sedimentary record. Nevertheless, the relative significance and differences between solar and thermal sensitization still not clear. The present study hypothesize that the sensitization of quartz grains in soil profiles is determined by burn-induced heating, while the cumulative sensitization over time is determined by the denudation rate.Considering this scenario, the goals of this research are as follows: i) carry out experiments to mimic the thermal and optical sensitization of quartz grains from soil profiles; ii) evaluate the variation in quartz's TL and OSL sensitivity in soil profiles from the Amazon, Atlantic Forest, Cerrado, and Caatinga biomes, which display different patterns of natural fires; iii) measure the TL and OSL sensitivities of quartz in a drilling core (925 m) from the Acre Basin that was obtained as part of the Trans-Amazon Drilling Project (TADP). The intent is to improve proxies to trace sediments from various climatic and vegetation contexts, that regulate the frequency and intensity of natural fires, and reconstruct environmental changes in western Amazonia during the Neogene and Quaternary, including the frequency of paleofires.