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An Overview Of Anorthosite-Bearing Layered Intrusions In The Archaean Craton Of Southern West Greenland And The Superior Province Of Canada: Implications For Archaean Tectonics And The Origin Of Megacrystic Plagioclase, Ali Polat, Fred J. Longstaffe, Robert Frei

Earth Sciences Publications

Anorthosite-bearing layered intrusions are unique to the Archaean rock record and are abundant in the Archaean craton of southern West Greenland and the Superior Province of Canada. These layered intrusions consist mainly of ultramafic rocks, gabbros, leucogabbros and anorthosites, and typically contain high-Ca (>An₇₀) megacrystic (2–30 cm in diameter) plagioclase in anorthosite and leucogabbro units. They are spatially and temporally associated with basalt-dominated greenstone belts and are intruded by syn-to post-tectonic granitoid rocks. The layered intrusions, greenstone belts and granitoids all share the geochemical characteristics of Phanerozoic subduction zone magmas, suggesting that they formed mainly in a …