Petrography of sulphate rocks from the Brinev gypsum deposit (Pripyat Trough, Belarus)
A.A. Makhnach, G.D. Streltsova, L.F. Gulis, N.D. Mikhailov
E-mail: gstrel@ns.igs.ac.by
E-mail: gstrel@ns.igs.ac.by
The composition and textural and structural features of sulfate rocks that form producing horizons at the Brinev gypsum deposit have been studied. It has been determined that gypsum, carbonate and anhydrite contribute to the composition of sulfate rocks in various spatial quantitative proportions being responsible for a petrographic type and structure of the rock. It has been revealed that bedded and vein sulfate bodies include one or several textural varieties of calcium sulfate. Bedded bodies of three upper horizons are formed by aggregates of spar, alabastrine and sugar-like gypsum; aphanitic anhydrite occurs in the lower bed of the fourth horizon in addition to gypsum. Conformable and cross veinlets are filled with selenitic and sugar-like gypsum. Some peculiarities of localization, structure and texture of bedded and veinlet sulfates suggest the crystallization and blastic origin of gypsum textural varieties.
Rock fissuring is of atectonic and tectonic origin. The larger disjactive disturbances are of tectonic nature: intraformational breccias and small cross veinlets are due to mainly gypsum tectonics, and irregular variations of hypsometric levels of beds or their absence and extented cross gypsum bodies – to fault tectonics and leaching of salt deposits.