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