Niekruszcowe składniki żył mineralnych w skałach staropaleozoicznego podłoża okolicy Zawiercia-Wolbromia

Abstract

Głównymi składnikami żył mineralnych oraz metasomatycznie zmienionych skał z ich otoczenia są: kwarc, kalcyt, chloryty (ripidolity o zmiennej zawartości żelaza) oraz minerały rudne. Rzadziej występują: dolomit, kaolinit, przerosty illit/smektyt, serycyt, skalenie potasowe (adular o niskim stopniu uporządkowania struktury), epidoty o zmiennej zawartości żelaza (pistacyt-klinozoisyt) oraz siarczany wapnia (gips, sporadycznie anhydryt). Minerały te tworzą różnorodne asocjacje ukształtowane podczas 2 lub 3 etapów minerałotwórczych. Ich genezę autorzy wiążą częściowo z działalnością magmową w badanym obszarze, częściowo zaś z procesami egzogenicznymi.  NON-ORE COMPONENTS OF MINERAL VEINS IN LOWER PALEOZOIC BEDROCKIN THE ZAWIERCIE – WOLBROM AREA The studies on mineral veins in Lower Paleozoic rocks comprised 16 borehole columns from the vicinities of Wolbrom, Ogrodzieniec and Zawiercie (Fig. 1). The veins vary in thickness from some hundredths of mm to a few cm, in places forming irregular swellings. Their boundaries are either sharp or blurred, with gradual passage to surrounding rock. The veins were found to consist mainly of quartz, carbonates, chlorites and ore-minerals (which are out of scope of the studies), accompanied by kaolinite,  sericite, illite-smektite intergrowths, feldspars, minerals of the epidote-clinozoisite group and calcium sulfates (Table 1).Carbonates are represented by calcite and, sometimes, dolomite. Optical properties of chlorites correspond to those of ripidolites with varying content of iron. Feldspars display features of adularia with low degree of structural ordering. Epidotes are represented by members differing in content of iron: from typical pistacite to varieties close to clinozoisite. Mixed illite-smektite structures represent disordered illite-montmorillonite intergrowths with about 50% share of swelling packets. Calcium sulfates mainly include gypsum as anhydrite occurs sporadically.The above mentioned minerals form various associations, from two- to six-component ones in the veins (Table 2). Some of these associations are of the paragenesis type whereas the others represent products of 2 to 3 mineral-forming events (Fig. 12).Components of the studied veins are the products of a wide range of temperatures, from relatively high (origin of epidote and adularia) to fairly low (origin of gypsum). The origin of epidote, K-feldspars, chlorites and, partly, quartz, sericite and calcite as well as ore minerals should be related to igneous activity in the studied area, i.e. with juvenile water rich in silica, potassium, calcium, aluminum and iron.In turn, kaolinite, montmorillonite, calcium sulfates, dolomites, and the youngest generations of quartz and calcite presumably originated from descent of solutions, in result of action of weathering processes on Lower Paleozoic rocks, exposed and subjected to erosion in certain time span.The origin of mineral veins was often accompanied by metasomatic action of solutions on surrounding rock. In the proximity of veins, there are most often found traces of silification, chloritization and ca1citization. In some borehole columns, there were also found epidotization, mineralization with ore minerals, feldspatization, sericitization, dolomitization and argillization. Some of these processes (carbonatization, kaolinitization and sericitization) were also effecting earlier formed components of the veins.The traces of hydrothermal mineralization found in the studied Lower Paleozoic rocks give further support to regional nature of these phenomena in the basement of the Silesian-Cracow Monocline.