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Type: Artigo de periódico
Title: Geology Of The Forquilha Eclogite Zone, Ceará Central Domain, Northwestern Borborema Province [geologia Da Faixa Eclogítica De Forquilha, Domínio Ceará Central, Noroeste Da Província Borborema]
Author: Ancelmi M.F.
Santos T.J.S.D.
Reginato R.A.
Amaral W.D.S.
Monteiro L.V.S.
Abstract: The retrograded eclogites of the Forquilha area have been characterized based on detailed geological mapping and systematic petrography. These rocks occur as boudins enclosed into ortho- and paragneisses and rarely in calc-silicate rocks along more than 16 km in a N-S trend, defining the Forquilha Eclogite Zone, in the NW portion of the Borborema Province. This zone is in tectonic contact with rocks of the Ceará Group that dominantly comprises metapelites and subordinately metacarbonatic and metamafic rocks metamorphosed under high-pressure granulite and upper amphibolite facies conditions. The retrograded eclogites show three important stages of retrometamorphism that can be described by the following reactions: 1) [ Grt + Cpx + Qtz + H2O → Pl + Amp] and [Grt + Cpx + Rt + Qtz + H2O → Amp + Ilm + Pl]; 2) [Omp → Di + Pl]; 3) [Grt + Di + Pl + H2O → Amp] and [Grt + Pl + Qtz + H2O → Grt2 + Pl (An) + Amp], besides incipient late formation of Fe-chlorite and actinolite. The retrogressive metamorphism occurred heterogeneously on these metamafic bodies. It was more intensive at the boudin rims and obliterated the higher P-T mineral paragenesis due to intense structurally controlled interaction with metamorphic fluids during progressive exhumation. These occurrences of retrograded eclogites might record a Neoproterozoic suture zone and are important geological features to understand the tectonic evolution of the Ceará Central Domain during the West Gondwana formation.
Editor: Sociedade Brasileira de Geologia
Rights: aberto
Identifier DOI: 10.5327/Z2317-48892013000200004
Date Issue: 2013
Appears in Collections:Unicamp - Artigos e Outros Documentos

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