Quaternary evolution of a Carpathian Foothills area: An example from the East Carpathians of Poland

Abstract

The East Carpathian Foothills of Poland witnessed two episodes of relief planation in the Pliocene, followed by formation of Early Pleistocene strath terraces preserved on flat-topped meander spurs in the San River valley at altitudes of 100-120 m above recent floodplains. In the following stages, intense erosion produced of a flight of strath terraces that are provisionally dated to the Narevian or Sanian-1 (Menapian or Elsterian-1; 75-80 m), Sanian-2 (Elsterian-2; 40-60 m), Odranian and Wartanian (Drenthe, Warthe; 20-30 m), and Vistulian (Weichse- lian; 8-16 m) times. During glacial stages, solifluction deposits mantled the feet of gentle slopes being coeval with fluvial deposition and accumulation of loesses and loess-like sediments on either side of the San River valley, particularly intense in the Weichselian. Interglacial warmings fostered downcutting of the pre-existing fluvial sediments as well as formation of fossil soils within loess sequences and deposition of peat in abandoned channels. In the Late Pleistocene and at the beginning of the Holocene, diversified tectonic movements took place leading to displacement of Weichselian and Holocene straths. During the Holocene, in turn, cut-and-fill terrace steps were shaped, organogenic sediments filled abandoned channels and oxbow lakes, and slopes became re-modelled by landslides and slopewash. The pattern of different types of relief, together with spatial distribution of topolineaments and some photolineaments in the eastern portion of the Polish Outer Carpathians, has been shaped due to mutual interactions between climatic, lithologic and tectonic factors. Well-pronounced topolineaments either follow fault-related zones of weakness, are associated with dense network of extensional cross-fold joints, or indicate recent reactiva-tion of some faults and/or joint sets