Influence of bedrock lithology, slope morphology, sedimentary charactheristics and eluvium cover on slope deformations in Jizerské hory Mts.

STOR T.; MOREIRAS S.M.; MARTINEK K.

Congreso; Mikulov Anthropology Meeting; 2015

During geological maping between 2008 and 2014 in Jizerské hory Mts. we recognized different types of slope accumulations here landslides. Their character and behaivour depend mainly on slope steepness, presence of tectonic structures or discontinuties, thickness of eluvium and thickness of sedimentary cover and as well on type of a bedrock lithology. Areas with fresh granite bedrock are more prone to rockfall and rock avalanche deposits; while weathered granitic outcroppings tend to leader debris flows/slides. Normally a thick layer of elluvium is identified in the last case being unstable water satured on deep relief. Outcroppingswhich are formed by metamorfic rocks (orthogneiss, phyllites, metamorfic schists) are associated withdebris flows and landslides with more fine-grained sedimentary infill and ?gentle? surface morphology. We compared 12 different accumulations. Tectonic structures and intensity of rock discontinuities have positive influence on generating potencial collapses. As well As we can see in Smědavská hora slopes and Oldřichov col area,water saturation of bedrock contributes to formation of debris flow accumulations more than rockfall and rock avalanche deposits. Despite the fact that weathering residue layer occur mainly on flat plateau and gently inclined slopes up to 5° with thickness up to a first few metres which grow up with altitude, few decimetres layer of eluvium on steeper slopes play important role to origin slope deposits potential and formation of debris flow in present. We compared 26 points by hand wells and artificial outcrops. Although we suppose influence of a releasing of horizontal stress which was imposed by continental glaciation retreat phase, on formation of slope deposits on northern slopes of Jizerské hory Mts., many questions are still not answered.