Mantle-derived Archaean monozodiorites and trachyandesites

The 2,680–2,750-Myr old1–5 intrusive granite–greenstone terranes6–8 in the Rainy Lake region, Ontario, and in, and adjacent to, the Vermilion District, Minnesota, of the Superior Province in North America, include a wide variety of volcanic and intrusive rocks with initial Pb, Sr and Nd isotope ratios close to those for the mantle4,5,9–12. The isotopic… CONTINUE READING