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Elsevier, Journal of South American Earth Sciences, (58), p. 188-209, 2015

DOI: 10.1016/j.jsames.2014.07.006

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Early to Late Paleoproterozoic magmatism in NE Brazil: The Alto Moxotó Terrane and its tectonic implications for the Pre-West Gondwana assembly

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Abstract

related and within-plate magmatism UePb and SmeNd geochronology Borborema Province (NE Brazil) a b s t r a c t The Alto Moxot o Terrane is a Paleoproterozoic inlier within the Transversal Domain of the Neo-proterozoic Borborema Province (NE Brazil). An isotopic and whole-rock geochemistry study has been performed in the Sucuru region (Paraiba State, NE Brazil) which revealed a long-lived evolution for this terrane. The first event is Siderian-aged, dated on 2.44 Ga, being represented by granitic to granodioritic banded orthogneisses and migmatites of the basement. They correspond to meta to peraluminous high-K calc-alkaline series, where geochemical patterns besides zircon features and Nd isotopic data indicate that they were formed in a convergent tectonic environment with reworking of an older Archean con-tinental crust. This basement was intruded by different magmatic suites through two distinct tectono-magmatic events. The older one is Rhyacian-aged recorded by emplacement of the Carmo mafic-ultramafic suite and Pedra d' Agua granitic suite, with ages varying from 2.15 to 2.0 Ga. The Carmo Suite shows compositions similar to tholeiitic and minor calc-alkaline series and geochemical patterns of a depleted source. These general chemical characteristics are compatible with an arc-related magmatism in early stages of subduction. The Pedra d' Agua suite corresponds to middle to peraluminous high-K calc-alkaline magmatism which presents a typical magmatic arc geochemical signature. The negative εNd (t) values suggest a strong continental component for genesis of these magmas. The last tectonomagmatic episode occurred in the Statherian-Calymmian boundary and is represented by bimodal magmatic as-sociation of the Serra da Barra Suite, dated around 1.6 Ga. The dominant felsic rocks present an evolved composition and correspond to typical metaluminous sub-alkaline suite. The trace-element and REE patterns of both mafic and mainly felsic rocks suggest a within-plate setting. The attributed source is of crustal derivation, which is supported by the negative εNd (t) values. A mantle plume can be invoked for mechanism of generation of the Serra da Barra magmatism. This polycyclic Paleoproterozoic evolution observed at Alto Moxot o terrane is also well documented in orogenic terranes worldwide, mainly those related to Atlantica supercontinent amalgamation. On the other hand, Statherian-Calymmian extensional event is also coherent with worldwide descriptions and are commonly referred to early break-up stage of the large Paleoproterozoic land masses.