Abstract
Ediacaran magmatism represents one of the most prominent features of the Borborema Province (NE Brazil), with the Umarizal intrusive suite a classical example of an anorthosite - mangerite - charnockite - granite (AMCG) association. This study presents new geochemical and petrological data, discusses its magmatic evolution, and compares the outcomes with similar rocks of Western Africa. The Umarizal suite displays mineral associations that crystallizated under high temperature (<900 °C) and pressure (up to 8 kbar) and low oxygen fugacity conditions that favored the formation of fayalite, magnetite, hypersthene, Fe-hornblende and annite. This generated transitional alkaline to calc-alkaline A-type magmas, which have been emplaced at intermediate to upper crust. Based on our results, we concluded that the several lithological componentes of the Umarizal suite resulted from varying degrees of interaction of melts derived from granulite-facies protoliths with crustal materials. It is considered a late-to post-tectonic Brasiliano/Pan-African orogenic context for the emplacement of this AMCG association along extensional shear zones.
Published Version
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