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

Autor(es)

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

• Tipo de documento: Artigo Científico
• Fonte: QUATERNARY GEOCHRONOLOGY; v. 36, p. 28-37, SEP 2016.
• Citações Web of Science: 1

Resumo

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)

• Processo FAPESP: 09/53988-8 - EMU: aquisição de sistema de datação por luminescência e de microamostrador de precisão, para o estudo de mudanças ambientais no Quaternário
• Beneficiário: Paulo César Fonseca Giannini
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 12/50260-6 - Estruturação e evolução da biota amazônica e seu ambiente: uma abordagem integrativa
• Beneficiário: Lúcia Garcez Lohmann
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
• Processo FAPESP: 14/23334-4 - Reconstrução de mudanças no sistema fluvial da Amazônia durante o Cenozoico tardio (<5 Ma) por meio da integração de análises por luminescência opticamente estimulada (OSL) e nuclídeos cosmogênicos (TCN).
• Beneficiário: Fabiano do Nascimento Pupim
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado