Produção Nacional
PETROGRAFIA E PETROQUÍMICA DOS GRANULITOS DA REGIÃO DE ITABUNA - BAHIA
1993; Sociedade Brasileira de Geologia; Volume: 23; Issue: 4 Linguagem: Inglês
10.25249/0375-7536.1993234356369
ISSN2177-4382
AutoresJOSÉ E. OLIVEIRA, Johildo Salomão Figueirêdo Barbosa, JOÃO B.A. ARCANJO,
Tópico(s)Geological and Geochemical Analysis
ResumoThe Early Proterozoic rocks of Itabuna region, southern Bahia, were separated into four main groups. The first one, the Ilhéus Complex (IC) is formed by bands of basic granulites with hornblende plus pyroxenes and mostly intermediate granulites (andesites and/or quartz diorites), these last ones with a high potassium calc-alkaline tendency. The second, the São José Complex (SJC) is essentially composed of basic (andesitic basalts and/or diorites) and intermediate granulites (andesites and/or quartz diorites) of low potassium calc-alkaline affiliation, but which include bands of garnet-bearing basic granulites (basalts and/or gabbros) of ocean floor or back-arc basin tholeiitic composition. The third group, the Ibicaraí- Buerarema Complex (IBC), and Rio Japu Complex, is made up mostly by intermediate granulites (andesitic basalts and/or diorites, andesites and/or quartz diorites, and dacites and/or tonalites) and acid granulites (rhyolites and/or trondhjemites), also with low potassium calc-alkaline tendency and which also exhibit bands of basic (basalts and/or gabbros) tholeiitic granulites of ocean floor or back-arc basin character. The fourth group is formed by plutonic bodies (monzodiorites, monzonites, syenites and granites) possibly derived from shoshonitic/alkaline magmas. These granulites may be correlated with those which occur to the north, where they before collision/obduction/deformation/metamorphism processes, as derived from a subduction zone near the Atlantic coastal region are considered, that generated arc/back-arc basin or active continental margin environments in the southeastern Bahia, during the Early Proterozoic.
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