Evaluating isothermal thermoluminescence and thermally transferred optically stimulated luminescence for dating of Pleistocene sediments in Amazonia |
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| Institution: | 1. IRAMAT-CRP2A (Institut de recherche sur les Archéomatériaux, Centre de Recherche en Physique Appliquée à l''Archéologie), UMR 5060 CNRS – Université Bordeaux Montaigne, Maison de l''Archéologie, F-33607 Pessac Cedex, France;2. Pôle d''archéométrie – Institut Français d''Archéologie Orientale, 37 rue al-Cheikh Aly Youssef B.P. Qasr el-Ayni 1152, 11441 Le Caire, Egypt;3. PACEA (de la Préhistoire à l''Actuel: Cultures, Environnement, Anthropologie), UMR 5199 CNRS – Université de Bordeaux, Avenue des Facultés, F-33405 Talence Cedex, France;4. Centre National de Préhistoire, Ministère de la Culture et de la Communication, F-24 000 Périgueux, France;5. Ministère de la Culture et de la Communication, Direction Régionale des Affaires Culturelles de Rhône-Alpes, CREPS, route de Salavas, F-07150 Vallon-Pont-d''Arc, France;6. Laboratoire de géologie de Lyon: Terre, planètes et environnement (LGL-TPE), UMR 5276 CNRS – Université Lyon 1, F-69622 Villeurbanne Cedex, France;1. Laboratory of Luminescence Dating, Institute of Nanoscience and Nanotechnology, National Centre for Scientific Research, N.C.S.R. “Demokritos”, Athens, 153 10, Greece;2. Department of Geophysics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan;1. Institute of Liberal Education, Kangwon National University, Chunchon, Kangwon-Do 200–701, Republic of Korea;2. Department of Physics, Kangwon National University, Chunchon, Kangwon-Do 200–701, Republic of Korea |
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| 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 ∼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. |
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| Keywords: | Luminescence dating TT-OSL ITL Amazonia paleogeography |
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