Neotectonic activity of Lubań Range (Gorce Mts.) based on morphometric indices

Abstract

The aim of this paper is to use a relative tectonic index (Iat) in order to evaluate tectonic activity in the intermediate mountain area of the Lubań Range. To estimate the tectonic activity in the study area, we analyzed 6 DEM derived geomorphic indices for 66 basins: the stream-gradient index (SL), asymmetry factor (Aß, basin shape ratio (B¡), hypsometric integral (Hi), valley floor width-valley height ratio (Vß and mountain-front sinuosity (Smß. These parameters were combined to obtain the relative tectonic activity index (Iat). According to Iat values, ca. 25% of the Lubań Range was classified as areas of relatively high tectonic activity and ca. 72% as moderately technically active. The Iat values suggest a higher relative tectonic activity in the western part of the range, since some morphometric indices, like HI and SL, indicate a higher rate oj tectonic uplift along the Dunajec Fault and normalfaults on the northern slopes oj the Luban Range. The rate ofthe tectonic uplift obtainedfrom the Iat values is similar to that derivedfrom river incision. Morphometric analysis as well asfield evidence ofactive tectonics, such as triangularfacets, suggest a high rate oftectonic uplift along the northern margins ofthe range and probably along the eastern slopes ofthe Lubań Range. The high relative tectonic activity on the southern slopes in the western part ofthe Lubań Range is probably related to active subsidence ofthe Nowy Targ Basin.