Recognition of insufficient bleaching by small aliquots of quartz for reconstructing soil erosion in Greece

Optical dating of sediments requires sufficient bleaching of the material to be dated. Using single aliquot techniques, the statistical parameter of the coefficient of variation v in combination with the reduction of mineral grains per aliquot enables the detection of insufficiently bleached samples. This was empirically tested on quartz extracts from the Greek study area, which were artificially bleached, differently dosed and then mixed to simulate insufficiently bleached samples. The single aliquot regenerative dose protocol was applied. The test measurements show that for the studied quartz material, the detection of insufficient bleaching is possible if small aliquots of 200-500 grains and a threshold value of v = 10% are used. The technique was applied to the age determination of colluvial and alluvial/torrential deposits from the study area, the Basin of Phlious in Greece. The optically stimulated luminescence age data allow reconstruction of the history of Holocene soil erosion, which essentially started in the 7th millennium BC, simultaneous with the onset of agricultural activities in the early Neolithic. (C) 2003 Elsevier Science Ltd. All rights reserved.