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|Type:||Artigo de periódico|
|Title:||1.57 Ga Protolith Age Of The Neoproterozoic Forquilha Eclogites, Borborema Province, Ne-brazil, Constrained By U-pb, Hf And Nd Isotopes|
|Abstract:||The 30km-long, N-S-trending Forquilha eclogite zone, occurs within a Paleoproterozoic block mainly composed of gneisses and migmatites, in the Ceará Central domain, Borborema Province, NE Brazil. The Forquilha eclogite zone contains lenses of high to ultra-high pressure metamafic rocks, found as granulites and amphibolites associated with kyanite-sillimanite gneisses. Three samples of clinopyroxene-garnet amphibolite yielded the U-Pb zircon ages of 1566±9Ma, 1547±37Ma and 1532±24Ma, interpreted as the timing of igneous crystallization of the mafic protolith. Additionally, zircon grains of a leucocratic layer of a metamafic rock and a retrograded eclogite provided the less precise U-Pb ages of 1613±40Ma and 1454±120Ma, respectively. Lu-Hf and Sm-Nd model ages provided TDM (Hf) between 1.55 and 1.81Ga with positive εHf values of+7.50 to+10.48, and TDM (Nd) ranging between 1.57 and 1.92Ga with positive εNd values of+1.84 to+4.36. It is believed that part of the rocks of the Forquilha eclogite zone were emplaced as mafic dikes in an extensional setting at ca. 1.57Ga.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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