Occurrence and geochemistry of metamafic rocks from the Forquilha Eclogite Zone, central Ceara (NE Brazil): geodynamic implications

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dc.contributor.authorAmaral, Wagner da Silva
dc.contributor.authorSaraiva Santos, Ticiano Jose
dc.contributor.authorWernick, Eberhard [UNESP]
dc.contributor.institutionUniversidade Estadual de Campinas (UNICAMP)
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.date.accessioned2014-05-20T14:17:19Z
dc.date.available2014-05-20T14:17:19Z
dc.date.issued2011-03-01
dc.description.abstractIn the northern region of the Borborema Province, a 30 km-long mafic/ultramafic belt of high pressure (HP) rocks called the Forquilha Eclogite Zone has been recently discovered in the Central Domain of Ceara State. The belt comprises three groups of rocks: ( I) garnet amphibolites, (2) retrograded eclogites and (3) clinopyroxene-garnet amphibolites, all of them being hosted in garnet +/- kyanite + sillimanite schists and orthogneisses which are often migmatized. The geochemical analyses of 30 representative samples confirm differences among the three groups that were initially classified by petrography. The garnet amphibolites are the most depleted rocks, with relatively flat rare earth element (REE)(PM) pattern and (SPIDER)(PM) pattern with negative Rb, Th, Nb, Sr and Zr anomalies. It is the most fractionated group, ranging from picrobasalts to andesites. Fractional crystallization and mineral accumulation are indicated by Eu and Sr anomalies. The data show geochemical affinities with,. island-arc basalts. The retrograded eclogites display flat (REE)(PM), but without Eu anomalies. Nb/La ratios are low and variable, as for slightly enriched MORB from ocean floor or intra-oceanic back-arc environments. However, a genetic link with the Group 1 rocks cannot be completely discarded. The clinopyroxene-garnet amphibolites are the most enriched group. (REE)(PM) and (SPIDER)(PM) patterns show many features of alkaline basalts. In the Nb/Yb versus Th/Yb diagram the data cluster near the E-MORB standard. Several geochemical aspects of these rocks fit well those from the HP/UHP Pan-African/Brasiliano Suture Zone in the Dahomeyides/Hoggar regions of West Africa. However, differences in their extent and lack of alignment preclude a direct correlation among these zones. Copyright (C) 2010 John Wiley & Sons, Ltd.en
dc.description.affiliationUniv Estadual Campinas, UNICAMP, Inst Geociencias, BR-13081970 Campinas, SP, Brazil
dc.description.affiliationUniv Estadual Paulista, UNESP, IGCE, São Paulo, Brazil
dc.description.affiliationUnespUniv Estadual Paulista, UNESP, IGCE, São Paulo, Brazil
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipIdFAPESP: 03/07663-3
dc.description.sponsorshipIdFAPESP: 07/58535
dc.description.sponsorshipIdCNPq: 42.0222/2005-7
dc.format.extent137-155
dc.identifierhttp://dx.doi.org/10.1002/gj.1224
dc.identifier.citationGeological Journal. Malden: Wiley-blackwell, v. 46, n. 2-3, p. 137-155, 2011.
dc.identifier.doi10.1002/gj.1224
dc.identifier.issn0072-1050
dc.identifier.urihttp://hdl.handle.net/11449/25192
dc.identifier.wosWOS:000289658400004
dc.language.isoeng
dc.publisherWiley-Blackwell
dc.relation.ispartofGeological Journal
dc.relation.ispartofjcr1.654
dc.relation.ispartofsjr0,846
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjectBorborema Provinceen
dc.subjectBrazilen
dc.subjectHP/UHPen
dc.subjectretrograded eclogitesen
dc.subjectPan-African belten
dc.subjectgeochemistryen
dc.titleOccurrence and geochemistry of metamafic rocks from the Forquilha Eclogite Zone, central Ceara (NE Brazil): geodynamic implicationsen
dc.typeArtigo
dcterms.licensehttp://olabout.wiley.com/WileyCDA/Section/id-406071.html
dcterms.rightsHolderWiley-blackwell
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Geociências e Ciências Exatas, Rio Claropt

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