Abstract
FIELD relationships and geochronological data have shown that the metamorphosed supracrustal rocks of the Isua area are the oldest known components of the Archaean complex of West Greenland1–4. Rb–Sr, U–Pb and Pb/Pb ages in the range ∼ 3,700–3,800 Myr have been reported from various units within the Isua supracrustals5–9. One of us (P.W.U.A.) has recently discovered occurrences of sulphide mineralisation, including galena, within the Isua supracrustals. Here we describe these occurrences and report Pb isotopic analyses for several galenas, one of which is uniquely unradiogenic for a terrestrial rock in both 206Pb/204Pb and 207Pb/204Pb ratios. Until now the least radiogenic ore leads came from the Barberton Mountain Land of southern Africa (see refs 10, 11) and from the Pilhara Goldfield region of Western Australia12. The least radiogenic rock leads have been reported from the ∼ 3,600–3,700-Myr-old Amîtsoq gneisses of West Greenland13–15.
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APPEL, P., MOORBATH, S. & TAYLOR, P. Least radiogenic terrestrial lead from Isua, West Greenland. Nature 272, 524–526 (1978). https://doi.org/10.1038/272524a0
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DOI: https://doi.org/10.1038/272524a0
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