Metamorphic vanadian-chromian silicate mineralization in carbon-rich amphibole schists from the Male Karpaty Mountains, Western Carpathians, Slovakia

Abstract

Mineralization, involving vanadian-chromian silicates, has been studied in Lower Paleozoic, carbon-rich amphibole schists with pyrite and pyrrhotite near Pezinok, southwest Slovakia. A detailed electron microprobe study has revealed the presence of V,Cr-rich garnet, clinozoisite, and muscovite, associated with amphiboles (magnesiohornblende, tremolite, actinolite, and edenite), diopside, and albite. The garnet contains 5-19 wt% V 2 O 3 , 5-11 wt% Cr 2 O 3 , and 2-13 wt% Al 2 O 3 (16-64 mol% goldmanite, 19-36 mol% uvarovite, and 9-59 mol% grossular end-members). The garnet is unzoned or shows V-rich cores and Al-rich rims, or irregular coarse oscillatory zoning with V, Cr, and Al, locally involving Ca and Mn as well. The V,Cr-rich clinozoisite to mukhinite and "chromian clinozoisite" contains 2-9.5 wt% V 2 O 3 and 1.5-11 wt% Cr 2 O 3 ; the muscovite contains 2.5-8 wt% V 2 O 3 and 0-7 wt% Cr 2 O 3 . The mineralization originated from primarily V-, Cr-, and C-rich mafic pyroclastic rocks, affected by volcano-exhalative processes. These rocks were weakly metamorphosed during early Hercynian regional metamorphism (M1), followed by late-Hercynian contact metamorphism (M2) with crystallization of V,Cr-rich silicates, diopside, amphiboles, phlogopite, titanite, albite, quartz, carbonate, pyrite, and pyrrhotite. The youngest Alpine(?) retrograde metamorphic event (M3) is connected with production of V,Cr-poor muscovite, clinochlore, clinozoisite, pumpellyite-(Mg), prehnite, quartz, and carbonates, under prehnite-pumpellite facies conditions.

Combustion Mineralogy and Petrology of Oil-Shale Slags in Lapanouse, Sévérac-le-Château, Aveyron, France

“…Retrogressive Cr-bearing andradite is known from the Jijal ultramafic complex in Pakistan (Jan et al, 1984). Retrogressive uvarovite is reported from amphibole schists of Slovakia (Uher et al, 2008). Retrogressive uvarovite is reported from amphibole schists of Slovakia (Uher et al, 2008).…”

Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobšiná, Slovakia

“…Chromium-bearing garnets are relatively rare and are associated with specific geological environments and geochemical conditions. In the Western Carpathians, only a few occurrences have been described, including Pezinok-Rybníček [73], Čierna Lehota [74], and Dobšiná [67].…”

Polymetamorphic greenschists with Al-rich green spinels (the Western Carpathian Mts.)

“…Higher Pressure-Temperature conditions of recrystallization (M 2 ), which are characteristic for contact-thermic processes, were observed on the whole pre-Carboniferous rock-sequence of the Malé Karpaty Mts. [7][8][9]. M 2 processes caused heating and recrystallization (dehydration) of original mineral sequence of [10].…”