ZŁOTO W ŻYŁACH KWARCOWO-SIARCZKOWYCH Z WIERCENIA DB-4 (REJON DOLINY BĘDKOWSKIEJ, POŁUDNIOWA POLSKA)

Abstract

GOLD IN QUARTZ-SULPHIDE VEINLETS FROM DB-4 DRILLHOLE (BĘDKOWSKA VALLEY, SOUTHERN POLAND)Abstract. Recent Polish Geological Institute investigations of the DB-4 drillhole cores from Będkowska Valley (southern part of Małopolska block) documented occurrence of gold in grey-greenish and brown Ediacaran metasedimentary rocks. Elevated concentrations of gold (up to 15 ppm) have been revealed in isolated samples from several intervals, mostly at depths of 253.0 and 584.5 m. Numerous quartz veinlets (up to 10 cm thick), quartz-sulphide and carbonate veinlets occur within those intervals. Gold-bearing mineralization coexists with pyrite and sphalerite veinings and impregnations in association with galena, chalcopyrite and minor arsenopyrite. Gold and electrum occur in a form of inclusions in pyrite, sphalerite-galena veinlets (which crosscut pyrite), and as fine-grained exsolutions(<0.1 mm in size) in quartz. Electrum is characterized by variable contents of silver, in a range from 19.7 to 46.9 wt %. In DB-4 profile, gold shows a positive correlation with arsenic, lead, copper, and zinc. Gold-hosted rocks display silification, epidotization, chloritization and calcitization. Granodiorite intrusion in the vicinity of drillhole and numerous intrusion-related Upper Carboniferous-Lower Permian dacite, diabase and andesite dikes which cut across the Ediacaran structurally-deformed metasediments implies that the formation of gold-bearing mineralization may relate to evolution of late-Variscan postmagmatic hydrothermal processes in zones affected by magmatic and tectonic activity.