Abstract
This paper presents a review of available lithostratigraphic and isotopic data, in addition to other information collected from projects of the Geological Survey of Brazil (SGB-CPRM), for the Rio Piranhas-Serido Domain (PSD). This domain is one of the tectonostratigraphic compartments of the central-northeast portion of the Borborema Province (Northeast Brazil), bound by the Picui-Joao Câmara, Patos and Portalegre shear zones. More recent isotopic determinations (U-Pb dating of zircon) and geological maps (usually on a 1:100000 scale) have clearly detected and/or redefined several units, e.g., the Amarante, Campo Grande, Granjeiro and Saquinho complexes, in addition to the Serra do Inga body (Archean), Arabia Complex (Siderian), Caico Complex and Serra da Formiga Suite (Rhyacian), Poco da Cruz Suite (Orosirian-Statherian), Serido Group (Ediacaran) and Ediacaran to Early-Cambrian magmatic suites, in addition to pegmatites and granitic pegmatites. With respect to the supracrustal rocks of the Serido Group, the deposition in the Ediacaran is based on field relations and on the ages of detrital zircons, which showed a greater contribution from Mesoarchean to Neoproterozoic sources, the vast majority of which may come from the PSD itself. Current records indicate that the evolution of the PSD started in the Eoarchean, and peaked in the Neoproterozoic with the Brasiliano event, which is characterized by sedimentation of the Serido Group, intrusion of plutonic bodies, deformation and metamorphism (especially at the regional level), in addition to the formation or reactivation of important shear zones. Such evolution is acknowledged on the basis of the accretion of oceanic arcs during the Paleoproterozoic (containing Archean fragments), including the generation of juvenile magmas and a protocrust (Caico Complex). The Neoproterozoic record, associated with the Brasiliano event, is considered by several authors as reworking with no or little contribution of juvenile material, with deposition of the Serido Group, emplacement of several Ediacaran to Early-Cambrian magmatic suites, accompanied by the formation of shear zones, predominantly in the southern and eastern portion of the domain.
Highlights
The Rio Piranhas-Seridó Domain (PSD) corresponds to a segment of the Borborema Province (Almeida et al 1977), encompassing part of the states of Ceará, Rio Grande do Norte, Paraíba and Pernambuco in northeastern Brazil
The PSD is composed of Archean nuclei, SiderianRhyacian gneissic-migmatitic blocks, bodies of augen Rhyacian-Statherian gneisses, Neoproterozoic metasupracrustal sequences and intense Neoproterozoic to EarlyCambrian magmatism, affected by or generated during the Brasiliano Orogenesis in the Neoproterozoic (Fig. 3)
Ediacaran magmatism in the PSD can be characterized by seven plutonic suites (Fig. 9): Jardim do Seridó, Conceição, São João do Sabugi, Itaporanga, Dona Inês, Caxexa and Umarizal, which have been described by several authors (e.g., Almeida et al 1977, Angelim et al 2006), Nascimento et al 2015, Cabral Neto et al 2019)
Summary
The Rio Piranhas-Seridó Domain (PSD) corresponds to a segment of the Borborema Province (Almeida et al 1977), encompassing part of the states of Ceará, Rio Grande do Norte, Paraíba and Pernambuco in northeastern Brazil. The boundaries of the PSD, in relation to the adjacent domains as well as to the Potiguar Basin, are highlighted by the contrast in the intensity of the magnetometric anomaly (reduction to the pole). This anomaly is strongly positive within the domain and medium to low in the adjacent domains (Fig. 2). Inside the PSD, several Archean, Paleoproterozoic and Neoproterozoic units have been mapped, as well as important extremely large shear zones. They are essentially dextral strike-slip shear zones (Malta, Santa Monica and Frei Martinho), implemented or reactivated during the Brasiliano event, affecting the main units of the domain
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