OSLdating of theMiddlePalaeolithicHotelCalifornia site,SierradeAtapuerca, north‐centralSpain

Abstract

In this study we present optically stimulated luminescence (OSL) dating results obtained at one of the most important open‐airMiddlePalaeolithic sites in theSierradeAtapuerca foothills –HotelCalifornia. We also assess the possibility of obtaining extended‐rangeOSLchronologies for a nearbyMiddlePleistocene fluvial deposit using several novel methods, namelyOSLdating of individual quartz ‘supergrains’, multi‐grain aliquot thermally transferredOSL(TT‐OSL) dating and the first application of a single‐grainTT‐OSLdating procedure. Four single‐grainOSLages constrain theMiddlePalaeolithic occupation ofHotelCalifornia to between 71±6 and 48±3 ka. TheHotelCalifornia single‐grain equivalent dose (De) distributions are highly overdispersed and contain several dose populations, which are probably attributable to post‐depositional sediment mixing, partial bleaching and intrinsic scatter. The reliability of multi‐grain aliquotOSLdating is compromised by the complex underlyingDedispersion affecting these samples, as well as by biasing multi‐grain averaging effects. Extended‐rangeOSLandTT‐OSLchronologies for the nearbyPicoRiver terrace are consistent with each other and with broad independent age control. These experimental approaches yield a weighted average age of 348±16 ka for terraceTA9of theArlanzónRiver sequence. Our results highlight the benefits of comparing ages obtained using severalOSLmethodologies to improve the robustness of luminescence chronologies. They also demonstrate the potential that single‐grainOSLtechniques offer for establishing improved age constraints on the many otherMiddlePalaeolithic sites found atAtapuerca and elsewhere across north‐centralSpain.