A STUDY OF THE CONTRIBUTION OF ISOTOPE GEOLOGY IN THE DEVELOPMENT OF EXPLORATION STRATEGY
The results of stable and lead isotope studies on several Irish metal deposits, many of them tungsten- bearing, indicate the following: item"(a)" There is an association with a particular and identifiable stratigraphic level on each side of Lapetus Ocean, i.e. in the Dalradian of West Ireland and the Lower Palaeozoic sequences of South-East Ireland. item"(b)" A wide spectrum of metals (Pb, Zn, Cu, W, Sn, Li, Mn, Sb, Au), although often not found together in the same place, have a common origin reflected in shared stratigraphic settings in the different terrains. item"(c)" Where metals are sited in veins or in granite, their pre-granite source is elsewhere but usually nearby in South-East and West Ireland. item"(d)" Meteoric water has played, at most, only a peripheral late-stage role in metal transport. item"(e)" There is a fundamental coherency in all of the Irish Palaeozoic lead deposits; the character of the lead involved varies with geography but not with time, indicating extraction from an evolving source. item"(f)" Metal deposition, as reflected in isotopic fractionation between coexisting minerals and by fluid inclusions, usually occurred at temperatures in excess of 300circC. item"(g)" In North-East Ireland, the development of Au- Sb-As veins at over 300circC can be separated from later lower-temperature base metal vein deposits.par The key to a successful search for metal deposits in the Irish Caledonides is likely to lie in a package of distinctive volcanogenic sediments deposited on the oceanic floor and intercalated into thicker continental margin sedimentary sequences on both its margins.
Bibliographic Reference: EUR 11628 EN (1988) FS, 103 PP., ECU 10, AVAILABILITY: EUROFFICE, LUXEMBOURG, POB 1003
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Record Number: 1989126111600 / Last updated on: 1989-06-01
Available languages: en