Neogene-Quaternary response of the Novohradske hory Mts. (Czech Republic) fluvial systems to tectonics - Analyses of morphotectonics, stream-length index and structural geology
Abstract
Based on comparison of morphotectonic analysis results with the SL index analysis, airborne geophysical measurements and field geological and structural data, possible Miocene to Holocene development of the landscape relief of Novohradske Mts. (southern Moldanubian Zone; Bohemian Massif) with a significant contribution of active faulting is interpreted. We suppose a polyphase reactivation of pre-existing faults under (a) the Miocene-Pliocene stress-field (regional similar to NNW-SSE extension) as (oblique) normal faults trending similar to SW-NE to similar to NW-SE were responsible for the subsidence of the Trebon Basin and Kaplice Furrow and (b) the Pliocene to Holocene stress-field (Shmax = 146.) when horizontal in the similar to NNW-SSE direction with possible activity of the prevailing similar to NNE-SSW trending faults as a sinistral strike-slips or weak reverse oblique-slip movement.
The second set of subvertical similar to WNW-ESE faults was predominantly reactivated in a dextral strike-slip regime or as gentle reverse oblique-slip faults. These Miocene to Holocene events reflect the coupling between the East-Alpine-Carpathian segment and its northern foreland, mainly due to northward motion of the African and the Arabian lithospheric plates.
The core of the Novohradske hory Mts. experienced a significant uplift compared to the neighboring areas of the Kaplice Furrow and the rebo.n Basin. The most significant uplift has been found near Rychnov nad Malsi, and on the tectonic border between the Kaplice Furrow and the Bukovsky hrbet Ridge.
This uplift took place during the late Pliocene and Pleistocene, after the sedimentation of lacustrine sediments in the Kaplice Furrow. Although the combination of GIS, morphotectonic and geophysical analyses with validation by field structural data does not provide the final proof of young tectonic activity, we conclude that there is strong indication of Neogene-Quaternary reactivation of several faults in the Novohradske Hory Mts.
Based on similar morphological features, it can be supposed that many areas in the Alpine Foreland and Bohemian Massif underwent similar tectonic evolution during the Miocene to Holocene era.