In situ-produced 10 Be and 26 Al indirect dating of Elarmékora Earlier Stone Age artifacts: first attempt in a savannah forest mosaic in the middle Ogooué valley, Gabon
Résumé
Discovered in 1987 by R. Oslisly, Elarmékora is a high terrace that, today, is situated 175 m above the Ogooué River in the historical complex of Elarmékora, attached to the Lopé National Park in Gabon, a World Heritage site since 2007. The site yielded a small lithic assemblage, including mainly cobble artifacts embedded within the one-meter thick alluvial material. Based on geomorphological and palaeoclimatological criteria, the preliminary dating suggested an age of 400 ka. However, Elarmékora could be a key site for Atlantic Central Africa if this lithic industry can be dated absolutely. In 2018 and 2019, two field trips were organized to collect surface samples as well as samples in vertical depth profiles with the aim of measuring their in-situ produced cosmogenic nuclide (10 Be and 26 Al) content. Results suggest a surface abandonment between 730 and 620 ka ago representing a minimum age for the cobble artifacts. Concurrently, technological reappraisal of the artifacts suggests an atypical lithic industry which should, for the moment, be considered as "undiagnostic" Earlier Stone Age. This age bracketing may be compared with a similar age range obtained for prehistoric occupations in Angola using the same approach. This age will place Elarmékora among the oldest evidence for the presence of hominins in western Central Africa and raises the question of a "West Side Story" to early human dispersals in Africa.
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