Carajás Mineral Province - Example of metallogeny of a rift above a cratonic lithospheric keel

The Carajás Mineral Province (CMP) is located on the southeastern margin of the Amazonian Craton, in northern Brazil. It is the largest producer of high-grade iron ore and a major world supplier of copper, nickel, manganese and gold. This article presents the CMP as a product of oblique rift evolution (2.76–2.06 Ga) controlled by the Canaã and Cinzento strike slip system. The Carajás rift is hosted in the tonalite-trondhjemite-granodiorite (TTG)-greenstone Rio Maria terrains (3.0–2.85 Ga). It overlies a subcratonic lithospheric mantle (SCLM) keel as indicated by seismic tomography and is filled by the Carajás plutonic-volcanic sedimentary sequences (CPVSS) that host the CMP. The rifting stage (Grão Pará Group) began with intense tholeiitic fissure volcanism with basalt and rhyolite flows, coeval intrusions of alkali granites and mafic-ultramafic bodies, BIFs, shales and restricted tuff beds. The Azul and Águas Claras Formations consist mainly of shales and sandstones deposited during the sag stage. The calc-alkaline signature of the Grão Pará metavolcanic rocks was demonstrated to reflect the composition of the melted TTG basement. The high magnesium and platinum-group elements (PGE) contents of Puma and Onça mafic-ultramafic complexes indicate extensive partial fusion, conditions that are indicative of a plume origin. We are proposing that CMP's IOCG deposits were formed from saline carbonate fluids exsolved from deep-seated metasomatic mantellic magmas (MMM), channelled and concentrated along jogs and step-overs in strike-slip fault systems in the Carajás rift.