Produção Nacional
RELAÇÕES ENTRE POSICIONAMENTOS DE PEGMATITOS E EVENTOS TECTONO-METAMÓRFICOS NO GRUPO SERIDÓ, NORDESTE DO BRASIL
2017; Sociedade Brasileira de Geologia; Volume: 22; Issue: 1 Linguagem: Inglês
ISSN
2177-4382
Autores Tópico(s)Geochemistry and Elemental Analysis
ResumoThe age relationships of pegmatites to the regionally important folding phases (F2 and F3) and their deformation features suggest the existence of two distinct suites of pegmatites in the Serido Group: an older (pre-F3) suite of highly deformed pegmatites showing, locally, tectonic fabrics related to F2 and/or F3; and a younger (late-post F3) suite of weakly deformed or undeformed pegmatites without any tectonic fabric. The major concentration of pegmatites, including members of both the suites, occurs within medium - to high-grade metasediments in the eastern part of the Serido belt. The tectonic structures and fabrics found in pegmatites of the older suite show that their emplacement began during the regional F2 tectono-metamorphic event and outlasted it. The structural relationships of pegmatites of the younger suite, together with their lackof planar and linear fabrics, suggest that their emplacement post-dates the phase of syntectonic crystalization/recrystalization related to the regional F3 tectono-metamorphic event. The ages obtained for two pegmatites of the younger suite are situated between 510 and 450 Ma, which suggests a late Brasiliano age for its emplacement. This pegmatite suite appears to be genetically related to the late-tectonic (570-510 Ma old) Brasiliano granites. The age of the older pegmatite suite, as also its relationship with the granites, cannot be established at present for lack of geochronological and geochemical data. However, there is no doubt that its emplacement occurred early in the tectono-metamorphic history of the Serido Group.
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