Rozwój strukturalny łupków łyszczykowych Pasma Kamienieckiego między Czerniawą a Rębiszowem

Abstract

 Wykorzystując metody analizy strukturalnej przedstawiono etapy rozwoju tektonicznego łupków Pasma Kamienickiego. Wyróżniono trzy generacje struktur charakteryzujące trójfazowy rozwój tektoniczny łupków oraz wykazano, że główna foliacja, penetratywna na tym obszarze, jest pochodzenia metamorficznego, a ściślej – efektem metamorfizmu dynamicznego związanego z pierwszą fazą deformacji. Foliacja ta nie naśladuje warstwowania sedymentacyjnego, a przebiega przeciętnie pod kątem 50–700 w stosunku do pierwszych struktur planarnych. STRUCTURAL DEVELOPMENT OF MICACEOUS SCHISTS OF THE PASMO KAMIENIECKIE RANGE BETWEEN CZERNIAWA AND RĘBISZÓW Micaceous schists of the Pasmo Kamienickie Range belong to the Karkonosze-Izera Block. They are distributed in the form of a narrow, sub-latitudinal zone from Lazne Libverda in Czechoslovakia to Wojcieszyce. The recorded linear, fold and planar structures indicate three-phase tectonic development of these rocks.The oldest structure are represented by narrow intrafoliation folds, the relics of which may be found in most competent rocks, mainly quartzite schists. These forms are close to isoclinal folds with angle between limbs varying from a few to about a dozen degrees and characterized by marked dispersion of axes. The first phase of folding was connected with complete transposition of original sedimentary structures. Foliation S1, parallel to axial planes of folds f1, developed in micaceous schists. At present, this is the only penetrative plane in the schists of the Pasmo Kamienickie Range.It is dipping steeply northwards in the whole area whereas axes of the first folds are E–W oriented in the vicinities of Przecznica and Czerniawa and they dip at the angle of about 45° near Gierczyn.The second phase of deformations resulted in folding of crystallizational foliation S1. Mesostructures of that phase are represented by crenulation folds and genetically related crenulation cleavage developed as either of the discrete or zonal type. Similar folds with specific geometry (with antiforms developed in the class 3 of J. Ramsay (1967) and synforms displaying features of the class 1) have developed in massive, medium- to coarse-laminated micaceous-quartz schists. Other fold structures of that phase of deformations include disharmonious, chevron and zig-zag folds.Crystallitazional foliation S2 developed in axial planes of some types of folds f2, and its intersection with planes S1 resulted in origin of lineation 12. Mesofolds f2 and lineations are normal to large asymmetric folds with SSW vergence and axes dipping to E, ENE and, sometimes, W and they as a rule appear in crest parts of the latter.Small-scale asymmetric chevron folds belonging to the third generation of mesostructures appear in anisotropy planes S2, especially in places where zones of discrete crenulation cleavage are wide.They are characterized by highly regular axial planes oriented at low angle to the planes S2. The crenulation foliation displays lineation related to intersection of S2 and S3 as well as wrinkling parallel to it. The lineation and axes of crenulation folds are set at an angle of about a dozen degrees. The folds f3 and lineation 13 are dipping at low angle to ESE, E, ENE.Similarly as in other areas without stratigraphic record, it is nowadays impossible to date individual stages of deformations of schists in the Pasmo Kamienickie Range. On the basis of radiometric datings of micas from some Izera rocks (M. Borkowska and others, 1980) and with reference to our alternative interpretation of the time succession of individual generations of micas, it is assumed that the youngest stage of deformations of rocks in the Pasmo Kamienickie Range has taken place before the Middle Carboniferous.