The genesis of Cu-bearing quartz veins by metamorphic remobilization from stratiform red bed deposits, SW County Cork, Ireland

Wen, N., Boyce, A.J. , Fallick, A.E., Ashworth, J.R. and Ixer, R.A. (1996) The genesis of Cu-bearing quartz veins by metamorphic remobilization from stratiform red bed deposits, SW County Cork, Ireland. Mineralogy and Petrology, 57(1-2), pp. 73-89. (doi: 10.1007/BF01161622)

Abstract

Polymetallicmajor veins of the West Carbery district (County Cork) are compared with the nearby stratiform-disseminated copper mineralization in metasedimentary rocks, containingminor veins (metamorphic quartz veins and veinlets). These stratiform deposits are hosted by non-marine Devonian sediments (Old Red Sandstone), metamorphosed in the Hercynian orogeny. In sulphides from the stratiform deposits and minor veins, isotopic compositions of sulphur (δ34S) range from − 21.00 to + 5.14%0, consistent with the vein sulphide being remobilized stratiform-disseminated sulphide, and the latter being of diagenetic bacteriogenic origin. Sulphate (barite), found in veins separate from the sulphides, has δ34S + 12.3 to + 15.7%0. consistent with groundwater origin. In minor-vein quartz, fluid inclusions have homogenization temperatures consistent with trapping under the estimated peak-metamorphic conditions (300–400°C, 1–3 kbar).

In the major veins, sulphide δ34S (−15.8 to −4.2 0) suggest remobilization of diagenetic sulphide. Oxygen and hydrogen isotopes suggest deposition from metamorphic fluids (calculated δ18OH2O approximately + 8 to + l3%0, measured range of δD −52.2 to −27.3%0). Immiscible C02-bearing fluids were trapped in the temperature range 280–350°C with fluid pressure < ca. 600 bar. The inferred pressure-temperature history is attributed to late-metamorphic uplift, with fluid pressures falling below lithostatic. The sulphide-bearing veins are interpreted as a small-scale example of redistribution of mineral deposits by metamorphic fluids.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Boyce, Professor Adrian and Fallick, Professor Anthony
• Authors: Wen, N., Boyce, A.J., Fallick, A.E., Ashworth, J.R., and Ixer, R.A.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Mineralogy and Petrology
• Publisher: Springer-Verlag
• ISSN: 0930-0708
• ISSN (Online): 1438-1168