Clément Gariépy, Denis Verner, Ronald Doig; Dating Archean metamorphic minerals southeast of the Grenville front, western Quebec, using Pb isotopes. Geology ; 18 (11): 1078–1081. doi: https://doi.org/10.1130/0091-7613(1990)018<1078:DAMMSO>2.3.CO;2
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Pb-isotope ratios of high-grade metamorphic minerals such as K-feldspar, biotite, magnetite, apatite, sillimanite, and garnet define collinear arrays on 207Pb/204Pb vs. 206Pb/204Pb diagrams. The samples are from a zone extending 35 km southeast of the Grenville front; the dates are interpreted to reflect peak granulite conditions during an Archean metamorphic event having a minimum age of 2.65 Ga. The gneiss was derived from preexisting crustal precursors and was barely affected by the Grenvillian event, a milder perturbation followed by rapid uplift.