Uwagi o orientacji i genezie ciosu w skałach kredowych niecki śródsudeckiej
Abstract
Remarks on the origin and orientation of joints in the Upper Cretaceous rocks of the Intrasudetic Basin
Abstract
Results are presented of measurements of joints in the Youngest Cretaceous sandstones and underlying marls of the Intrasudetic basin. The joint orientation was presented on Schmidt stereographic projections and on rose diagrams. Two genetically different joint systems have been differentiated: (a) primary joints, which form a regional system of similar orientation in the whole investigated area, and (b) secondary joints, the orientation of which and frequency of occurrence depends on local tectonic causes. In the author's opinion the views concerning tectonic origin of joints perpendicular to the true bedding and showing constant orientation in the whole area of the Intrasudetic basin are difficult to elucidate. The attempts to explain it by fault- or fold tectonics are difficult to accept. No explanation of the primary joint is presented but, in the author's opinion, it is older than the tectonic movements that have caused the deformation of the Cretaceous cover in the Intrasudetic basin. Other cause should be looked for to elucidate this problem.