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Notes: Abstract The epimetamorphic Devonian-Lower Carboniferous formations from the Romanian Carpathians, dated by palynological and K/Ar absolute age analyses are similar as regards their facies and ore development, to the Paleozoic formations of Silesia and Central Europe. Consequently, the Hercynian eugeosyncline was extended southwards over the Carpathian area, where its deposits have undergone a probably sudetic regional metamorphism under epizonal conditions. One might draw the conclusion that there exists a genetic unity between the Devonian-Lower Carboniferous basic magmatic products and the associated ores from the Carpathians and the Hercynian of Europe. In the Carpathians there may be distinguished two Hercynian metallogenetic provinces related to the eugeosyncline stage: a) an ore province characterized by volcanogene-sedimentary iron ore deposits connected with the Devonian Diabase-Spilite magmatism and b) an ore province represented by polymetallic sulfide ore deposits related to the Lower Carboniferous metarhyolites and metaquarzkeratophyres.

Notes: Abstract The Freda-Rebecca Mine is currently the largest gold producer in Zimbabwe. The ore deposit is hosted by two main shear systems crosscutting the Rebecca diorite and Bindura granodiorite (2.65 Ga) as well as Shamvaian metasediments, which are affected by contact metamorphism. Following the intrusion of the Bindura granodiorite, intensive hydrothermal alteration developed preferentially in the dioritic part of the igneous complex (Rebecca diorite). The hydrothermal alteration started with an extensive K-dominated hydrothermal metasomatism in the whole Rebecca diorite. It was followed by less penetrative hydrothermal alteration developed preferentially near shear zones and veinlets. Hydrothermal metasomatism caused microcline and biotite formation, prevailing in the Rebecca diorite. Two main stages of post-metasomatic hydrothermal alteration and mineralization were distinguished, based on spatial relationships between different minerals and some geochemical aspects. In the first stage, an actinolite-tourmaline-arsenopyrite mineralization formed, which is characterized by Ni-Co arsenopyrite associated with actinolite, tourmaline and quartz. The second, lower temperature stage gave a polyphase gold-rich mineralization that developed in four phases which are distinguished by different parageneses including: Phase 1. Actinolite, chlorite, clinozoisite/epidote, quartz, calcite, arsenopyrite, pyrite, pyrrhotite, chalcopyrite. Phase 2. Chlorite, epidote, calcite, gold, native Bi, Bi-Pb sulfides, galena, chalcopyrite, fahlore, pyrite, Fe-gersdorffite. Phase 3. Epidote, calcite, (Ni, Co, Fe) As S phases, Co-Fe-gersdorffite. Phase 4. Chlorite, calcite, quartz. The gold mineralization is exclusively associated with phase 2 and developed in three sulfide parageneses: – Gold + Bi-Pb sulfides + bismuth + chalcopyrite + galena, associated with chlorite (Au 1). – Gold + galena + pyrite, associated with calcite and chlorite (Au 2). – Gold + pyrite + Fe-gersdorffite, associated with epidote, chlorite and calcite (Au 3). The hydrothermal alteration and mineralization formed after the consolidation of the Rebecca diorite and Bindura granodiorite, most probably in the postmagmatic cooling stage. The mineralization was emplaced either synchronously or subsequently to the shear zones which crosscut the consolidated pluton. Not all shear zones are mineralized and different shear zones show different amounts of mineralization and hydrothermal alteration. Thus, it is suggested that during the cooling stage of the pluton and subsequent to the formation of the K-metasomatic zone (microcline + biotite), hydrothermal fluids preferentially followed just forming or pre-existing shear zones. It cannot be excluded that this process developed in a plutonic porphyry copper-like environment, in which the classically hydrothermal zonation did not form due to synchronous tectonic disturbance, which preferentially drives the hydrothermal flow along shear zones. Mineral parageneses and data from chlorite geothermometry indicate that the different stages and phases of hydrothermal alteration reflect cooling stages of the hydrothermal system, from 〉300 °C in the first stage to about 150 °C in the last phases.

Notes: Summary The stilpnomelane minerals in the epimetamorphic series of the Romanian Carpathians are divided into four genetic groups. Some ferrostilpnomelanes from metamorphic iron-, manganese- and sulfide-ores have been studied optically, chemically, by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, and IR absorption spectroscopy. Several conclusions on the chemical constitution and the widespread occurence of ferrostilpnomelane in the metamorphic ores of the Carpathians are given.

Notes: Zusammenfassung Ilvait wurde in den polymetamorphen Eisenerzen von Ruschita als Rekristallisationsprodukt einer hochtemperierten banatitischen Kontaktmetamorphose mit Siliziumzufuhr in Magnetitskarnen, die aus regionalmetamorphen, ursprünglich vulkanogen-(magmatogen-)sedimentären Eisenkarbonaterzen gebildet wurden, aufgefunden.