CALCLITHITES OF THE KROSNO ZONE IN THE EAST CARPATHIANS (UKRAINE)

Results of carbonates distribution in the flysch rocks of the Krosno Zone (Ukrainian Carpathians), which are composed mainly by interstratification of sandstones, argillites and aleurolites, and sporadically limestones, dolostones and marls as well as estimations of contents are analysed in this article. Carbonates are widely distributed in variable amounts in the rocks outcropped into the new Beskyd tunnel at the Carpathians watershed and surrounding area. Most high values of carbonates (up to 77,11 wt. %) as well as its lowest contents (a few per cent) were found in different sectors. According to X-ray powder diffraction observations on whole-rock samples carbonates are represented by calcite and dolomite. Dolomite is dominant phase and its total amount is about three times more than calcite. Two main different age morphological and mineralogical generations of carbonates are distinguished within the flysch rocks after petrographic studies and microbeam analyses. Early generation of the carbonates is represented by coarse grained detrital dolomite and finer calcite as cement. Late generation of big in size crystals of carbonates is main component of the carbonate, carbonate-quartz, and carbonate-sulphide druses and veins, which are distributed locally. Studied carbonate-bearing rocks are regarded as calclithites after the Folk's classification due to significant amounts of terrigenous carbonates. Carbonates from the initial flysch rocks have δ13C and δ18O values similar to those of the typical marine limestone carbonates and are limited in a relatively narrow field. It is additional evidence of local sources for the flysch formations rich in carbonates.