Wyniki badań minerałów ciężkich skał węglanowych cechsztynu obniżenia nadbałtyckiego

Abstract

RESULTS OF EXAMINATION OF HEAVY MINERALS IN THE ZECHSTEIN CARBONATE ROCKS OF THE PERI-BALTIC SYNECLISESummaryCore samples of 9 bore holes situated within the Peri-Baltic syneclise, i.e. Prabuty IG-l, Olsztyn IG-2, Pasłęk IG-l, Kętrzyn IG-2, Klewno 1, Kętrzyn IG-l, Bartoszyce IG-l, Gołdap IG-l, have been a basis to examine mineral composition of heavy fraction of the Zechstein carbonate horizons. The mineral composition of the heavy fraction (Figs. 1–8) illustrates a quantitatively varying inflow of fragmental material and points to a diversified shore line of the basin during the sedimentation of the individual Zechstein stages. It is possible that the original range of the basin of Werra cyclothem was considerably greater than the present-day extent of this stage. The allogenic minerals of carbonate rocks of this stage (horizon 2) prove that at that time rocks of Krynki, Wojnów, and Czarna Hańcza series, as well as granitoids and sedimentary rocks older than Zechstein were at least partly exposed and eroded in the central part of the Mazury-Suwałki elevation (Fig. 9).A rejuvenation of the erosional profile within the area of the Mazury-Suwałki elevation, and a displacement of the shore line northwards and north-westwards (Fig. 10) are reflected in the mineral composition of heavy fractions in the near-top portion of the carbonate rocks of the Werra cycothem (horizon 4). At that time denudation comprises predominantly the Ełk intrusion rich in egyrin. A considerable inflow of detrital material is noted in the heavy fraction at the near-top portion of the carbonate rocks of the Stassfurt cyclothem (horizon 6). The basin was alimented also with the porphyraceous granites and with the metamorphic rocks ascertained by means of geophysical methods in the western part of the Mazury-Suwałki elevation (Fig. 11). The carbonate deposits of the Leine cyclothem within the Peri-Baltic cyclothem were intensely destroyed, mainly due to the activity of the pre-Triassic erosion (Fig. 12). There are preserved only rocks of the zone remote from the sea shore, in which the heavy fraction is markedly enriched in chlorite.