Plio-Pleistocene paleodrainage reconstruction using moldavite-bearing and morphostratigraphically related deposits (Southern Bohemia, Czech Republic)

Abstract

The area of Southern Bohemia between Novohradské hory Mountains and the Třeboň and Budějovice Basins – the Novohradské Foothills (in the south of the Czech Republic) is known for the occurrence of moldavites. These tektites are abundant in fluvial Koroseky sands and gravels. This study focuses on reconstructing the paleostreams, which deposited the moldavite-bearing sediments, and their relationship to present streams. Based on a review of the deposits' occurrences, a connection between moldavite-bearing sediments and deposits of the present watercourses, Vltava, Malše, Stropnice and Svinenský, is proposed. The link between moldavite-bearing deposits and the current streams were further supported by analyses of river geometry (longitudinal profiles, stream gradient) and terrain morphology (valley floor ratio, basin asymmetry). It is suggested that the moldavite-bearing deposits were sedimented during the Pliocene or Pleistocene by predecessors of the present streams. The occurrences of particular fluvial deposits and changes in terrain morphology and river geometry can be traces of changes in the river network and the dynamic evolution of local relief induced by tectonic activity during the Pliocene and Pleistocene.