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Characterization and application of violet stimulated luminescence signals of quartz for dating of fluvial sediments in Amazonia

Grant number: 19/04059-6
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): October 01, 2019
Effective date (End): February 28, 2022
Field of knowledge:Physical Sciences and Mathematics - Geosciences
Principal Investigator:André Oliveira Sawakuchi
Grantee:Pontien Niyonzima
Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Neogene and Quaternary evolution of the Amazonian river system has been linked to climate, sea level and tectonic changes and they operate in different timescales from few thousands to millions of years. So far, absolute ages for the Amazonian fluvial record (siliciclastic sediments) are restricted to the Holocene and Late Pleistocene, hardening the correlation with long term climate, sea level or tectonic changes. Different types of Optically Stimulated Luminescence (OSL) techniques were applied to determine ages for the Amazonian fluvial sedimentary record, but available luminescence dating techniques are not suitable to obtain sediment deposition ages beyond the late-mid Pleistocene (~500 ka). Thus, new luminescence dating methods have to be developed and tested to constrain the age of sedimentary units in Amazonia beyond the late Pleistocene. This is critical to improve the understanding about the landscape history of Amazonia and evaluate its role for biota diversification. In this context, the dosimetric potential of Violet Stimulated Luminescence (VSL) of quartz has been explored as a means to extend the dating age range to cover the full Quaternary. Despite the encouraging results showing desirable dosimetric signal characteristics, it is still needed that the proposed protocols require to be further improved, and samples from different geological settings need to be investigated, as the VSL properties could vary among quartz from different geological settings. This PhD research project will contribute to improve the geochronological methods for age determination of sediments in the hundred thousand years to few million years timescale, possibly covering the whole Quaternary period. This contribution will be achieved by studying of VSL signals in quartz representative of South American sediments and develop and test VSL dating protocols to be used in dating of Amazonian sediments beyond the OSL dating limit (>150-250 ka). The target sedimentary units for VSL dating will be the Içá, Solimões and Novo Remanso Formations, as well as their correlative units in eastern Amazonia. The ages of these sedimentary units are critical to understand the landscape changes giving origin to the transcontinental Amazon River and its tributaries, which represent the world´s largest fluvial system. (AU)