A review of lead and sulphur isotope investigations of Irish sediment-hosted base metal deposits with new data from the Keel, Ballinalack, Moyvoughly and Tatestown deposits.

Abstract

New Pb isotope data together with previously published data fall into two distinct clusters: to the S and E 206Pb/204Pb approx 18.23, 207Pb/204Pb approx 15.58, 208Pb/204Pb approx 38.09. To the N and W the corresponding ratios are: 17.98, 15.53 and 37.85, respectively. Additional data, however, suggest a single continuum of isotopic characteristics which appear to depend only on geographical location and not on style of mineralization. Sulphur isotope ratios are highly variable. The sulphur appears to have been derived from shallow and deep sources, while the lead is solely of lower crustal origin.-R.E.