Neotectonic mobility of the Roztocze region, Ukrainian part, Central Europe: insights from morphometric studies

The results of geological, geomorphic and hydrogeological research indicate spatially variable neotectonic activity of the Ukrainian part of the Roztocze region. This activity is confirmed by analysis of some geometric and morphometric coefficients (especially drainage basin elongation ratio, drainage basin circulatory ratio, drainage basin shape and lemniscate coefficient), which were calculated for 1646 drainage areas of the 3rd to 6th order, and morphometric linear coefficients (mountain-front sinuosity index and valley floor width-valley height ratio coefficient), which characterise the fault scarps. The south-western margin of the Rava Roztocze and Yaniv Roztocze regions, following NW-SE-trending faults, belongs to structures of the 1st or 2nd class of relative tectonic activity. On the other hand, in the north-eastern marginal zone in the Ukrainian part of the Roztocze region, a relatively active segment comprised between Maheriv and Zhashkiv shows a characteristic NW-SE orientation of valleys, controlled by a network of secondary sub-parallel faults. In the southern part of the analysed area, the Stavchanka River drainage basin related to the NW-striking fault zone, and the sub-parallel edge of the zone of the Vereshytsia-upper Mlynivka transverse depression are relatively active. Some relatively inactive areas are those of smaller drainage basins of the 3rd to 6th order, located within the zone of the main watershed between the Rata and Lubaczówka rivers in the Rava Roztocze region and the Zubra and Poltva rivers in the Lviv Roztocze region.