Late Quaternary Activity of the Sudetic Marginal Fault in the Czech Republic: A signal of Ice Loading?
Abstract
The study area is situated in the north-eastern part of the Bohemian Massif in central Europe and comprises the SE part of the NW-SE trending Sudetic Marginal Fault (SMF) with pronounced mountain front. Fourteen new trenches were excavated at the locality Bila Voda combined with geoelectric profiles (ERT) to study 3D distribution of the truncated alluvial fan on the NE block and to find the ""feeder channel"" as the source of the deposits.
We consider a small drainage of about 30-45 m to the southeast of the fan apex as the feeder channel. It gives us left-lateral slip for the ~25 ka alluvial fan, corresponding to a long-term slip rate of ~1.5 mm/yr.
As the Holocene deposits do not show significant displacement, most of the recorded slip took place during late Pleistocene with slip rate 1.8 to 2.8 mm/yr. The acceleration of slip rate was probably due to ice-loading/deglaciation of the Weichselian ice-sheet, which had its margin about 150 km from the locality at ~20 ka.