Evaluating isothermal thermoluminescence and thermally transferred optically stimulated luminescence for dating of Pleistocene sediments in Amazonia

Author(s)

Pupim, Fabiano do Nascimento ; Sawakuchi, Andre Oliveira ; Mineli, Thays Desire ; Nogueira, Luciana

• Document type: Journal article
• Source: QUATERNARY GEOCHRONOLOGY; v. 36, p. 28-37, SEP 2016.
• Web of Science Citations: 1

Abstract

The paleogeography of Amazonia lowlands during the Pleistocene remains hampered by the lack of reliable absolute ages to constrain sediment deposition in the hundred thousand to few million years timescales. Optically stimulated luminescence (OSL) dating applied to quartz has provided important chronological control for late Quaternary sediments, but the method is limited to the last similar to 150 ka. In order to extend the age range of luminescence dating, new signals from quartz have been investigated. This study tested the application of isothermal thermoluminescence (ITL) and thermally transferred optically stimulated luminescence (TT-OSL) signals of quartz for dating of fluvial terraces from eastern Amazonia. ITL and TT-OSL signals measured in a modern fluvial sediment sample have shown small residual doses (4 and 16 Gy), suggesting adequate bleached sediments for the target dose range (>150 Gy). This sample responded well to dose recovery test, which showed that the ITL and TT-OSL signals grow to higher doses compared to the doses estimated by the conventional OSL signal. The ITL signal saturated for doses significantly lower than doses reported in the literature. Most dating samples were beyond the ITL saturation doses and only TT-OSL signals were suitable to estimate equivalent doses. Burial ages ranging from 107 to 340 ka were estimated for the fluvial terraces in the lower Xingu River. The main ages uncertainties are related to dose rate changes through time. Despite the uncertainties, these ages should indicate a higher channel base level during the Middle Pleistocene followed by channel incision, possibly due to episodes of increased precipitation in the Xingu watershed. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 09/53988-8 - Acquisition of a luminescence dating system and a precision microsampler for the study of environmental changes in the Quaternary period
• Grantee: Paulo César Fonseca Giannini
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 12/50260-6 - Structure and evolution of the Amazonian biota and its environment: an integrative approach
• Grantee: Lúcia Garcez Lohmann
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 14/23334-4 - Coupling Optically Stimulated Luminescence (OSL) and Terrestrial Cosmogenic Nuclides (TCN) analysis to reconstruct changes in the Amazonian fluvial system in the Late Cenozoic (<5 Ma)
• Grantee: Fabiano do Nascimento Pupim
• Support Opportunities: Scholarships in Brazil - Post-Doctoral