Luminescence and radiocarbon dates from alluvial sediments, Podhale, Central Europe-A methods comparison

Optically stimulated luminescence (OSL) and radiocarbon (14C) techniques were employed to investigate the absolute ages of alluvial sediments in Podhale in the West Carpathians, southern Poland. This is an approach to (i) testing the credibility of the above dating methods by their reciprocal age control and (ii) further implications to regional geochronology and to dating campaigns of alluvial sequences elsewhere. Nine geological sections comprised of mineral and organic material were selected for the study. Our age determinations range from 26.9 to 2.27 ka, and are in good geochronological order. OSL age estimates show good agreement with independent ages from radiocarbon dating. However, in three alluvial successions the discrepancy between the resulting ages is considerable. We attribute the difference to the partial bleaching, and organic material redeposition. We also report on an age reversal of sediments in a single geological section. This might have been resulted from the alluviation-erosion scheme of meandering rivers over a millennial time-scale, i.e. the dominance of channel migration, point bar deposition (lateral accretion), and crosswise erosion. Finally, new geochronological data are provided abolishing sediment age assumptions based on uncertain chronostratigraphical approaches.

Automated summary

This study used optically stimulated luminescence (OSL) and radiocarbon (14C) techniques to investigate the absolute ages of alluvial sediments in Podhale, southern Poland. The results showed good agreement between OSL age estimates and independent ages from radiocarbon dating, with the exception of three alluvial successions. A phenomenon of age reversal in sediments was also observed in one geological section, which might be attributed to the alluviation-erosion scheme of meandering rivers over a millennial time-scale.