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Defining a chronological framework for the Middle Stone Age in West Africa: Comparison of methods and models for OSL ages at Ounjougou (Mali)

Published inQuaternary geochronology, vol. 29, p. 80-96
Publication date2015
Abstract

Ounjougou is the name of a large complex of archaeological sites, that were extensively studied between 1997 and 2008 by the international team of the “Human settlement and palaeoenvironment in West Africa” project. This complex is important because well stratified Palaeolithic sites in West Africa are rare, and because it covers a long period of time (most of the Upper Pleistocene and Holocene) and exhibits a wide set of technical cultures. Therefore, for the first time it is possible to propose a chronological framework for the human settlement in this region that can be related to other technical cultures in Africa and to palaeoenvironmental data. The purpose of this paper is to present the OSL dating results obtained from 57 sediment samples that led to this framework. Measurements were first performed between 2004 and 2006 in Oxford (School of Geography), using micro-aliquots (2e10 grains) OSL and ICP-MS for determination of equivalent doses and beta-dose rates, respectively (gamma dose rates being deduced from field gamma spectrometry). More recently, new measurements were done on 28 samples of this former set at the IRAMAT-CRP2A laboratory in Bordeaux, where “true” single quartz grain OSL and high resolution gamma spectrom- etry measurements were performed. Both sets of results are, for all but two samples, statistically consistent with each other. A consistent chrono-stratigraphic framework can thus be deduced, covering the Upper Pleistocene. It suggests that the region was regularly visited during this time interval and more particularly during Marine Isotope Stage 3, when groups with different technical cultures followed each other relatively rapidly.

Keywords
  • Palaeolithic
  • West Africa
  • OSL
  • Single grain
  • Small aliquots
  • Bioturbation
Citation (ISO format)
TRIBOLO, C. et al. Defining a chronological framework for the Middle Stone Age in West Africa: Comparison of methods and models for OSL ages at Ounjougou (Mali). In: Quaternary geochronology, 2015, vol. 29, p. 80–96. doi: 10.1016/j.quageo.2015.05.013
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ISSN of the journal1871-1014
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