Zonación mineralógica y evolución de los fluidos en el skarn Copina, provincia de Córdoba (64° 39? O; 31°30? S)

FRANCHINI, MARTA; RAÚL LIRA; JORGE SFRAGULLA

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 1998 vol. 53 p. 197 - 211

0004-4822

Skarn Zonation and Fluid Evolution in Copina, province of Córdoba, Argentina. Copina skarn occurs in the eastern contact zone of the Late Carboniferous-Early Devonian granitic Achala intrusive complex, in the Oriental Pampean Ranges of Argentina. It is hosted by wall rocks of the heterogeneous, Upper-Precambrian metamorphic basement and a pegmatite body. Five zones of skarn, successively, pyroxene zone, garnet zone, vesuvianite zone, quartz-vesuvianite zone and wollastonite broadly correspond with varying degrees of replacement of pegmatites, schist-amphibolites and calcic-magnesian marbles and they appear to pass laterally into one another. Pyroxene is Mg rich (Hd15-38; Jo0.5-5) and Mg/Fe ratio is always greater than 1. Garnet (Ad1-43; Py0.5-15) contains between 0,07 to 0,99 wt % fluorine, shows more compositional variations than pyroxene and Al/Fe is always greater than 1. Vesuvianite is iron poor and contains between 1 and 1.70 wt % fluorine. The fluid inclusion analyses in pyroxene, garnet, vesuvianite, wollastonite, epidote and quartz suggest that skarn formed between 420° and 140°C from fluids with moderate to low salinity (between 23 and 1 wt. % eq. NaCl). Temperature along the skarn section diminishes away from the pegmatite whereas saline concentrations are higher in more distal zones. Estimated pressures of the skarn formation from fluid inclusion data (