Central Irish sulphur isotope data in the light of the rift geological-metallogenic model

Abstract

The current state of central Irish sedimentary-exhalative metallogenetic theory is summarily reviewed. There is disagreement concerning the significance of primary sulphur in the genesis of the Tynagh/Silvermines ore deposits, the most popular view being that seawater sulphate, via biogenic reduction processes provided the bulk of the sulphur. It is shown that the extreme physico-chemical environmental conditions envisaged in a model which associates sulphide genesis with rifting may provide a framework wherein inorganic fractionation processses in primary sulphurous fluids may have contributed to a greater extent than currently recognised in producing the measured isotope distribution patterns at Tynagh and Silvermines. It is also noted that if catastrophic sulphide genesis on the scale of the Irish model were an historically recurring global event it might assist towards an explanation of the known isotopic history of the whole world ocean.