1.88 Ga Sao Gabriel AMCG association in the southernmost Uatuma-Anaud Domain: Petrological implications for post-collisional A-type magmatism in the Amazonian Craton

In the southernmost Uatuma-Anaua Domain, central Amazonian craton (Brazil), crop out 1.98 Ga basement inliers represented by (meta)leucosyenogranites and amphibolites (Igarape Canoas Suite), 1.90-1.89 Ga high-calc-alkaline granitoids (Agua Branca Suite), a 1.88-1.87 Ga alkali-calcic A-type volcano-plutonic system (Iricoume-Mapuera), Tonian SiO2-satured alkaline granitoids, 1.45-1.25 Ga orthoderived metamorphic rocks (Jauaperi Complex) and Orosirian-Upper Triassic mafic intrusions. New data on petrography, multielementar geochemistry, in situ zircon U-Pb ages and Nd and Hf isotopes of alkali-calcic A-type granites (Sao Gabriel Granite, Mapuera Suite) and related rocks are indicative of a 1.89-1.87 Ga volcano-plutonic system integrated to the Sao Gabriel AMCG association. Its magmatic evolution was controlled by the fractional crystallization combined with magma mixing and cumulation processes. Nd isotope values (epsilon Nd-t values = -3.71 to +0.51 and Nd T-DM model age = 2.44 to 2.12 Ga) and U-Pb inherited zircon crystals (2115 +/- 22 Ma; 2206 +/- 21 Ma; 2377 +/- 17 Ma, 2385 +/- 17 Ma) of the sao Gabriel system indicate a large participation of Siderian-Rhyacian crust (granite-greenstones and granulites) and small contribution of Rhyacian mantelic magma. epsilon Hf-t, values (+5.2 to -5.8) and Hf TOM ages (3.27-2.14 Ga) also point to contribution of Paleoarchean-Rhyacian crustal melts and small participation of Siderian-Rhyacian mantle melts. Residual melts from the lower crust have been mixed with basaltic melts generated by partial melting of the subcontinental lithospheric mantle (peridotite) in a post-collisional setting at 1.89-1.87 Ga. The mafic melts of such a mixture could have been originated through partial melting of residual ocean plate fragments (eclogites) which ascended onto a residual mantle wedge (hornblende peridotite) and melted it, resulting in modified basaltic magma which, by under plating, led heat to the anatexis of the lower continental crust. This widespread alkali-calcic A-type magmatism was caused by destabilization and magmatic reactivation in the Ventuari-Tapajos and Central Amazonian Provinces, resulting from the Ventuari-Tapajos collision periods. Younger igneous reactivations have been registered at 1.45 to 1.25 Ga,-1.0 Ga and-100 Ma, culminating with the production of mafic and felsic alkaline magmas, along of the northern border of the Amazon Basin. (C) 2017 Elsevier B.V. All rights reserved.