KVARTÉRNÍ SEDIMENTY NA SEVERNÍM PŘEDHRADÍ LOKALITY POHANSKO U BŘECLAVI

Sedimentological study on the Northern bailey of the fortified site Pohansko allows identification of 9th lithofacies and 2 facies associations. The lower facies association is interpreted as an infill of fluvial channels (mostly mid-channel dunes) with two cycles of filling. The fluvial channels were relatively shallow and broad (high width/depth channel ratio) and they point to braided fluvial style and channel migration. The upper fluvial association reflects significant change of the fluvial style. The sedimentary infill of the upper fluvial association is interpreted as deposits of levee and overbank deposits. Results of the OSL dating for the sample of lower facies association provide an age of 13.5 ky. Such age can be correlated with the Upper Pleistocene Allerød Interstadial (13.7‒12.9 ky BP), i.e. relatively warmer phase of the Weichselian late glacial. Data of OSL dating for two samples from the upper facies association were 11.8 ky and 10.3 ky BP. The upper age can be correlated with Younger Dryas (12.9‒11.7 ky BP) whereas the lower one to Preboreal. The deposition of the upper facies associations are therefore interpreted as Uppermost Pleistocene to Early Holocene in age.