OSL age determinations of Pleistocene fluvial deposits in Central Amazonia

Anais da Academia Brasileira de Ciências

Emílio A.a. Soares²  Sonia H. Tatumi¹  Claudio Riccomini¹ 

[1] ,Universidade Federal do Amazonas Departamento de Geociências Manaus AM ,Brasil

关键词: crystal luminescence dating;    Quaternary;    fluvial terraces;    Central Amazonia;    datação por luminescência de cristais;    Quaternário;    terraços fluviais;    Amazônia Central;   

DOI  :  10.1590/S0001-37652010000300017

来源: SciELO

【 摘 要 】

Absolute dating methods have been used in chronological studies of geological processes and sedimentary units of Quaternary age in Central Amazonia, Brazil. Although radiocarbon dating has been very useful in archaeological research and soil studies, the temporal interval of this method is inefficient in evaluating the sedimentation aspects and geological events from the beginning of the Quaternary in the Amazon basin. The use of crystal luminescence dating has been one of the most promising tool for determining the absolute dating of Quaternary deposits in the Amazonian region. Optically stimulated luminescence (OSL) dating, following the MAR and SAR protocols, in a tectonic-sedimentary study of Quaternary fluvial deposits in the confluence area of the Negro and Solimões rivers, indicated ages from 1.3 (Holocene) to about 67.4 kyears (Late Pleistocene) for these sediments. Low radioactive isotope concentrations were found about 2ppm for 235U and 238U; 5ppm for 232Th; and the 40K concentrations were almost zero. A comparison was made between MAR and SAR protocols taking into account the fluvial depositional process.

【 授权许可】

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