EVIDENCE FOR DIFFERENTIAL CRUSTAL UPLIFT BETWEEN THE NEIGHBOURING KAMIENICA AND OCHOTNICA RIVER VALLEYS IN THE POLISH OUTER WESTERN CARPATHIANS

Young tectonic movements in the Carpathians, both vertical and horizontal ones, display local variations. The Dunajec River valley is one of the areas where this differentiation has been documented best. New data on differentiated tectonic uplift, based on the study of changing elevations of five levels of fluvial strath terraces, were obtained in the lowermost reaches of two Dunajec's tributaries: Kamienica and Ochotnica. The results indicate a change in the rate of valley bottom incision during the Pleistocene. Initially, the rate of incision was higher in the Kamienica River valley during ca. 600-350 ka BP. Later, since ca. 130 ka BP until now, the proportion became reversed and the rate of incision was nearly twice as fast in the Ochomica River valley than in the Kamienica River valley. This is probably related to the mobility of the overthrust of the Krynica slice onto the Bystrica slice, both building the inner portion of the Magura Nappe. Reactivation of this thrust may be a result of neotectonic activity of large-scale faults situated at the depths of 5-20 km and possibly rooted in the Palaeozoic-Mesozoic basement.