Contrasting Pb isotopes of Archaean and Palaeoproterozoic sulphide mineralisation, Disko Bugt, central West Greenland |
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| Authors: | H Stendal |
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| Institution: | (1) Geological Survey of Denmark and Greenland (GEUS), Thoravej 8, DK-2400 Copenhagen NV, Denmark Phone: +45 38142208; Fax: +45 38142220 E-mail: hst@geus.dk, DK |
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| Abstract: | Sulphide separates from mineralisation in Archaean and Palaeoproterozoic host rocks of the Disko Bugt area, central West
Greenland, have been analysed for trace elements and Pb isotopes. Isotopic compositions of lead from sulphide separates of
Archaean supracrustal rocks show wide variations. Archaean semi-massive sulphides and sulphides separated from felsic metavolcanites
yield an errorchron age of 2821 +77/−82, with a model μ1 value of 7.36; this is comparable to the estimated age of the supracrustal rocks. The two most prominent mineralised sites,
the Andersen and Eqip prospects, have their own unique Pb isotope pattern; the Andersen prospect is considered to represent
the result of an upper crust of Palaeoproterozoic process. The sulphide separates of Palaeoproterozoic epigenetic mineralisation
hosted in shear and fault zones in the supracrustal rocks has a common origin, e.g. linked to a metamorphic peak and/or hydrothermal
alteration. Gold-bearing samples indicate a local origin for associated sulphides; no regional processes seem to be involved
in the formation of the gold occurrences.
Received: 17 March 1997 / Accepted: 8 July 1997 |
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