Wiek osadów tarasu zalewowego i holocenski rozwój doliny rzeki Lubrzanki w rejonie Cedzyny w Górach Świętokrzyskich
Abstract
AGE OF FLOOD TERRACE DEPOSITS AND HOLOCENE DEVELOPMENT OF LUBRZANKA RIVER VALLEY, THE CEDZYNA REGION THE HOLY CROSS MOUNTAINS Summary Paper presents discussion about genesis of Holocene lithofacies infillings of Lubrzanka river valley, their stratigraphy and possible paleomorphology interpretations. Such studies were supplied with age dating 14C method) of tree trunks from valley deposits, outcroping in river banks near bridge in Cedzyna (fig. 1). The Lubrzanka alluvial complex of Holocene age covers erosional basement, cutted at the end of Vistulian and beginning of Holocene within glacial and glacifluvial deposits (fig. 2, 3). Its profile consists of gravel-boulder channel pavement (beds no 5 on fig. 2 and no 3 on fig. 3) at bottom, gravelly sands of meander belt (bed no 6 on fig. 2 and no 4 on fig. 3) and tree trunks covered with flood muds and sands of paleochannel infills (beds no 7, 8 on fig. 2 and no 5, 6 on fig. 3). Age data of tree trunks are: for samples from I outcrop - 1510±50 and 1650±50 mln BP and for II• outcrop - 1800± 50 mIn years BP. They suggest early Middle SubatIanticum period for their transport and respectively older and younger time of under- and overlaying deposits (fig. 4). Between Vistulian and Lower Holocene primary braided pre-Lubrzanka river changed to meandering type (fig. 4), forming erosion channel and sediment infill. The meandering phase of river development has lasted till Middle Subatlanticum (SA2 ). During early Middle Subatlanticum lateral channel migration has cutted at the base valley slopes and involved tree slides. In Middle SubatIanticum meanders have stabilized and floods have been more frequent, leaving muds, regarded as youngest, post-Middle Subatlanticum member of Holocene. Recently Lubrzanka river straIghtens its channel and rarely bar accumulation is visible.Issue
Section
Geochemia, mineralogia, petrologia
