Brekcje w stratyfikowanych złożach rud cynku i ołowiu obszaru śląsko-krakowskiego

Abstract

BRECCIAS IN STRATIFIED ZINC AND LEAD ORE DEPOSITS IN THE SILESIAN-CRACOW AREASummaryThe present authors describe breccias found to occur the Silesian-Cracow zinc and lead ore deposits. According to the occurrence conditions, forms, composition of fragmental fraction, and kinds of cementing material the rocks here considered have been subdivided into: a – brecias of dolomite fragments with sulphide cement, occurring in sheet and nest forms, locally in larger assemblages, as a rule uncomfortably in relation to the adjacent rocks; b – dolomite ore breccias built of carbonate rock fragments and metallic ore fragments, with carbonate-clay cement; these breccias, usually occurring in the ner-fault zones, represent a type tectonic breccia; c – metallic ore breccias that consist of sulphide fragments, with dolomite-detrital cement they make nest-like forms. The knowledge of the character of these breccias and of their occurrence allowed both conditions and succession of their origin to be determined. Dolomite breccias that appear in sheet-like forms are, most probably, of diagenetic origin. They were formed almost contemporaneously with the main development phase of the deposit. Both dolomite and metallic ore breccias, found to occur in the nest-like forms were in all probability, produced due to karst processes and remobilization of ore minerals concentrated during the sedimentary phase of the deposits. The dolomite-metallic are breccia is of tectonic provenance. Its presence proves the posit-depositional nature of the disjunctive tectonics that developed within the previously existing deposits. The tectonics did not affect, however formation process of the mineral deposits considered.