Análise estrutural e metamórfica da região de Sucuru (Paraíba): implicações sobre a evolução do Terreno Alto Moxotó, Província Borborema

Abstract

Inserted on the Alto Moxotó Terrane of the Borborema Province, the Sucuru region (Paraíba state, Brazil) includes two dominantly pre-Ediacaran tectono-stratigraphic domains, bounded by an expressive thrust shear zone (Carmo SZ). The first domain has a metaplutonic nature, being formed by granodioritic to migmatitic orthogneisses (Floresta Complex) cut by several intrusive suites. These suites comprise a unit of mafic-ultramafic nature (Malhada Vermelha), a second one mainly of granitic-granodioritic composition (Pedra d’Água) and a last suite whose composition ranges from syenitic to syenogranitic (Serra da Barra). On the second domain predominate migmatitic paragneisses from of the Sertânia Complex.All these units were cut by Cambrian-Ediacaran felsic dykes and A-type granites. Three tectonic events were recognized. The first Dn episode represents a thrusting with tectonic transport to NW-NNW, being important the Sucuru and Carmo shear zones. The D n+1 episode is a transcurrent event of Ediacaran age, being important in regional context the Coxixola and Congo shear zones. The final progressive late Ediacaran-Cambrian Dn+2 episode, culminated with the emplacement of the Sucuru dyke swarm and the Prata and Serra da Engabelada A-type granites. Petrographic evidences show that the Dn episode reached its metamoprhic peak on the granulitic or eclogitic facies, whose paragenesis was after re-equilibrated to the amphibolite during the D n+1 event. The Dn+1 episode developed mylonitic corridors on the amphibolite facies with associated migmatization, while the Dn+2, event reached a greenschist facies restrict to influence of the late and post-tectonic intrusives. The occurrence of garnet amphibolites with symplectite texture along the metamorphic path Mn-Mn+1 suggests that the thrust event represented a high pressure metamorphic episode, indicating a probable Paleoproterozoic suture.