SPINELE CHROMOWE Z ZACHODNIEJ CZĘŚCI MASYWU GOGOŁÓW–JORDANÓW, POŁUDNIOWO-ZACHODNIA POLSKA

Abstract

THE CHROMIAN SPINELS OF THE GOGOŁÓW–JORDANÓW MASSIF, SOUTHWESTERN POLAND

Abstract. The chromian spinel of the Gogołów–Jordanów Massif, southwestern Poland, is hosted by a serpentinized peridotite that builds a part of the Ślęża ophiolite complex. The chemical character of the chromian spinel indicates that the ophiolitic rocks were derived from depleted mantle peridotite of harzburgite and subordinate dunite compositions. The mantle rocks were initially formed at a mid-oceanic ridge and subsequently thrust at a supra-subduction zone. The chromian spinel frequently displays optical and geochemical zoning. Three zones can be identified from core to edge: inner core representing the original composition of the chromian spinel; narrow Cr-rich ferrichromit zone; and outer – magnetite zone. The chromian spinel zonation is interpreted to be a result of serpentinization rather than magmatic or metamorphic processes. Geochemical data obtained from the chromitite and chromian spinel have been shown in a table. Two trends were achieved considering the chromian spinel. The first trend shows redistribution of trivalent cations, where Cr₂O₃ and Al₂O₃ diminishes from the first zone up to the third zone and the second trend indicates Fe₂O₃ cations that increase from the first zone up to the third zone. Few Ni and Cu sulfide inclusions were found in the chromian spinel, too small to take EPMA data.