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O terreno Alto Moxotó no leste da paraíba ("Maciço Caldas Brandão")

2001; Sociedade Brasileira de Geologia; Volume: 31; Issue: 2 Linguagem: Inglês

10.5327/rbg.v31i2.932

2317-4889

Benjamim Bley de Brito Neves, Mário da Costa Campos Neto, W. R. Van Schmus, Tânia María Gomes Fernandes, Solange Lucena De Souza,

Geological and Geochemical Analysis

The Alto Moxoto Terrane (TAM), at the east of Paraiba State is mostly composed of sheared orthogneisses, porphyritic granodioritic gneisses and it bears an imbricated sheet of Al-rich (garnet-biotite-sillimanite) gneisses, deeply affected by migmatization phenomena. This litho-structural assemblage is drawing a regional asymetric antiformal structure, with its axial zone running parallel to the BR-230 highway (E-W trending). It is limited in both, north (Alto Pajeu terrane) and south (Rio Capibaribe terrane) sides by important shear zones, which are feather faults connected with the development of the Pernambuco lineament, to the southwest. The adopted designation of is based upon its singular geological features, in terms of lithological and structural characteristics, Paleoproterozoic in age and sharp limits with the different confining terranes. TAM is here considered as a mega-fragment of the Atlântica Supercontinent, that was built up by the Paleoproterozoic Collage (Transamazonian) and that was preserved in the framework of West Gondwana (Brasiliano/Pan African Collage) as a terrane. This terrane shows conspicuous continuity to the far interior of the province, to the southwestern part of Pernambuco State, and so doing, it demontrates that the former designation of Caldas Brandao Massif must be ruled out, as obsolete for many reasons. Geochronological determinations using Rb-Sr, Sm-Nd and U-Pb methods confirm the Paleoproterozoic age of this terrane, with the presence of some Archean protoliths as well as the various degrees of structural reworking and isotopic reseting promoted by the Brasiliano Cycle. This cycle was responsible for some intrusive granites, for most of the general geological features, like usual informal limits and even the present shape of the TAM, a typical reworked basement inlier.