Struktury szkieletowe w leukogranicie izerskim okolic Kopańca i Małej Kamienicy

Abstract

SKELETAL STRUCTURES IN THE IZERA LEUCOGRANITE, IN THE VICINITES OF KOPANIEC AND MAŁA KAMIENICASummaryA number of test pits have been made in the vicinities of Kopaniec and Mała Kamienica (Figs. 1, 2), within the Świeradów Zdrój unit, on the northern slope of the Izera Mts. (Lower Silesia). The main background of the geological structure of the region in study is that of the Izera leucogranite (mainly quartz and albite) that, according to K. Smulikowski (H. Teisseyre, K. Smulikowski, J. Oberc. 1957), was formed due to the influence of sodium, boron and fluorine upon the Izera gneisses.Fragments of older rocks of Proterozoic age (Fig. 3), such as micaceous schists, amphibolite schists, biotite quartzites, quartz laminae (during the pre-granitization period quartz occurred within the micaceous schists as sheet veins of secretion origin), Izera gneiss, leucogranites and granite-gneiss are found to occur with in leucogranites. Measurements of foliation planes of these rocks demonstrate a NW–SE direction and steep dips towards NE and SW (Fig. 4). B – lineation (B1eA, B2eA – early Assyntian) in these rocks dips mainly towards NW and SE (Fig. 5).Due to their orientation, both types of mesoscopic structures may be correlated with analogous structures round beyond the area of leucogranite occurrence. Thus, the isolated fragments of the older rocks may be thought to represent autochthonous (skeletal) enclaves. Hence, we may assume that the leucogranites are here autochtonous and are formed in situ, at the cost of gneisses, granite-gneisses and leucogranites. Whether they have been formed of micaceous schists and amphibolites that constitute enclaves within their body, it can be explained only by means of detailed petrographic and  geochemic examinations. Most probably, the schists undergo granitization. Gneisses formed in this way are, after removal of iron, are an object of homogenization, and with the inflow of boron, fluorine (?) and sodium pass into leucogranite. This in turn was formed under static conditions immediately after the young Assynthian movements. Leucogranite here considered represents a post-kinematic rock there.