Thermoluminescence dates and palaeoenvironmental information of the late Quaternary sand deposits, Tierra de Pinares, Central Spain

A large amount of Quaternary palaeo-environmental evidence lies within the terrestrial aeolian sediments filling the Duero basin in central Spain. Previous work has identified a number of stratigraphical units although the absolute age and origin of some of these is equivocal. The uppermost unit, the focus of this paper, is a widely distributed sand which covers most of the Tierra de Pinares, north of Segovia. Detailed investigations of an exposure at Burgomillodo reveal over 35 m of laminated and cross-bedded sand from which seven thermoluminescence dates were obtained. The bedding structures indicate a northwesterly palaeowind direction, different from the present dominating westerly winds. Two phases of sand deposition are identified at the site with evidence of erosion and reactivation phases. An upper unit of ca. 7 ka during the warm-aridity of the Atlantic period and a lower unit between 12.5–11 ka coinciding with the cold-aridity of the Younger Dryas event. The latter, in which at least 25 m of sand were deposited at the site, is the dominant phase and is coincident with what has been identified elsewhere in Spain from biological data as a period which was both cold and dry. The Burgomillodos site, therefore, represents the first sedimentological evidence for this arid phase in the Younger Dryas in central Spain.