Copper and other mineralization in metamorphosed red beds, West Carbery area, South West Cork, Ireland

• Main Author: Ni, Wen
• Published: University of Birmingham 1991
• Subjects: 622
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543607

More than 100 mineralized localities have been found in the west Carbery area. The stratiform mineralisations are mainly hosted in the top of the predominantly,red coloured Devonian West Cork Sandstone Formation. "Major" sulphide-quartz veins are mainly, hosted in the base of the overlying Devonian Coomhola Formation where green-grey colour is dominant. Apart from the dominant copper sulphides, gold, native bismuth, and a large variety of Cu, Bi, Sb, As and Pb bearing sulphosalts have been found in the vein type mineralisations. Two metamorphic stages metamorphism) have (burial metamorphism and tectonic been recognized. Textures and compositions of phyllosilicates, carbonate compositions and reflectance of carbonaceous materials (graphite) have been used to estimate the metamorphic temperature. The estimated peak metamorphic temperature is 350±25°C and pressure is likely to be -2 kbar on regional geological evidence. Fluid inclusion study and ore mineralogy suggest that "major veins" formed at a temperature of about 300o C.- The trapping pressure obtained from Group 2 subgroup· B inclusions of Ballycurnmisk Veins is about 2 kbar and from other inclusions is < 1kbar. Stable isotope study suggests that vein forming fluids are typical metamorphic fluids. Sulphur from stratiform localities was probably bacterially reduced and sulphur in the "major veins" may be. metamorphically modified from the same ultimate source.