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Type: Artigo
Title: Vestiges Of A Continental Margin Ophiolite Type In The Novo Oriente Region, Borborema Province, Ne Brazil
Author: Araujo Pitombeira
Joao Paulo; Amaral
Wagner da Silva; Uchoa Filho
Evilarde Carvalho; Fuck
Reinhardt Adolfo; Dantas
Elton Luiz; Parente
Clovis Vaz; da Costa
Felipe Grandjean; Vieira Verissimo
Cesar Ulisses
Abstract: The Novo Oriente Group is a restricted well-preserved metasedimentary sequence, composed of two tectonic-stratigraphic sequences in the southwestern portion of the Ceara Central Domain, NE Brazil. The Bonsucesso Formation comprises mainly quartzite and metamafic rocks and the Caraubas Formation is dominantly metapelitic, with chemical sedimentary contribution, metamafic and metaultramafic rocks. New integrated field, geochemical data and Sm-Nd isotopes of the metaultramafic and metamafic rocks of the two formations have been investigated in order to determine their tectonic setting. The metaultramafic rocks are dominantly composed of deformed and undeformed serpentinites, chloritites, actinolitites, talc-chlorite schists, serpentine-talc schists, talc-rich siliceous rocks and subordinated listwanites. Geochemical data indicate that the serpentinites correspond to rocks resulting from the alteration of dunites depleted in HREE, similar to the pattern presented by subduction-zone serpentinites generated from exhumed sub-continental peridotites and hydrated during ocean-continent transition (OCT) rifting. The metamafic rocks, represented by metagabbros, hornblende metagabbros and metabasalts, consist of basic rocks of basaltic and tholeiitic affinity with signatures between E- and N-MORB and variable contamination by crustal components similar to the rocks formed from the interaction between mantle plumes and heavily thinned continental crust. Isotopic analysis indicates crustal assimilation with negative epsilon Nd and Paleoproterozoic T-DM ages. The data suggest that metaultramafic and metamafic rocks correspond, respectively, to continental sub-lithospheric mantle exhumed in an area of ocean-continent transition (OCT), and mafic magmatism associated with the development of a magma poor passive margin generated by the break-up of the Rodinia Supercontinent, which was later dismembered by the Brasiliano/Pan-African Orogeny collisional phase and preserved as a Continental Margin Ophiolite type. (C) 2016 Elsevier Ltd. All rights reserved.
Subject: Novo Oriente
Metaultramafic Rocks
Metamafic Rocks
Cm Ophiolite Type
Editor: Pergamon-Elsevier Science LTD
Citation: Journal Of South American Earth Sciences. Pergamon-elsevier Science Ltd , v. 73, p. 78 - 99, 2017.
Rights: fechado
Identifier DOI: 10.1016/j.jsames.2016.11.007
Date Issue: 2017
Appears in Collections:Unicamp - Artigos e Outros Documentos

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