Stratigraphy, tectonics and detrital zircon U-Pb (LA-ICP-MS) geochronology of the Rio Preto Belt and northern Paramirim corridor, NE, Brazil

Abstract

Two important Proterozoic metasedimentary sequences, the Rio Preto and Santo Onofre Groups, crop out along the northwestern margin of the São Francisco craton and in northern Paramirim corridor, respectively. The Rio Preto Group, involved in the eponymous fold-thrust belt along the northwestern cratonic boundary, comprises the Formosa (garnet schist, quartz-mica schist, quartzite, chlorite-sericite schist and ferriferous quartz schist) and Canabravinha (quartzite, micaceous quartzite, metarhytmite, phylite, schist and metaturbidite) formations. The Santo Onofre Group occurs exclusively in the Paramirim corridor, and is composed of quartzite and minor carbonaceous or Mn-rich phylite. These units record sedimentation in shallow to deep-water marine settings related to rift basins, and were deformed and metamorphosed under greenschist facies conditions during the Brasiliano orogeny. Here we present 427 new detrital zircon U-Pb ages, which constrain the maximum depositional ages of ca. 971 Ma for the Santo Onofre Group, ca. 912 Ma for the Canabravinha Formation, and ca. 965 Ma for the Formosa Formation of the Rio Preto Group. Our data suggests that the Santo Onofre and the Rio Preto Groups accumulated in two distinct basin settings. The latter, composed mostly of sandy rocks, would represent a relatively stable, shallow-marine shelf environment. The Rio Preto Group, with metadiamictite, quartzite, pelitic and rhythmitic rocks, represents a shallow to deep marine environment influenced by gravity flows. Both groups were probably deposited in the Late Tonian, and are potential correlatives of the lower (pre-glacial) units of the Macaú-bas Group of the Araçuaí belt. KEYWORDS:Detrital zircon U-Pb geochronology, Brasiliano orogeny, sedimentary provenance, Rio Preto Belt, Paramirim corridor. RESUMO: Duas importantes sequências metassedimentares proterozoicas ocorrem ao longo da margem noroeste do Cráton do

Early to late Neoproterozoic subduction-accretion episodes in the Cariris Velhos Belt of the Borborema Province, Brazil: Insights from isotope and whole-rock geochemical data of supracrustal and granitic rocks

“…The Brejo Seco and Paulistana complexes in the Riacho do Pontal Belt are interpreted as the result of post-convergence extension at 900-880 Ma (Caxito et al, 2016;Salgado et al, 2016), probably marking the first stages of an orogenic collapse phase, slightly similar to our younger obtained zircon age. In effect, Post-Cariris late Tonian and Cryogenian A-type granites, rift sequences and mafic-ultramafic intrusions of similar age are also found in the belts surrounding the northern São Francisco Craton margin, in the Rio Preto (Caxito et al, 2014c;Alcântara et al, 2017), Riacho do Pontal (Caxito et al, 2016;Salgado et al, 2016) and Sergipano (Oliveira et al, 2010) belts. In addition, zircon populations that range from 850 to 1000 Ma are present in several widespread Ediacaran metasedimentary and metavolcanosedimentary sequences throughout the province, such as the Araticum Complex of the Sergipano Fold Belt (Lima et al, 2019) and Cabrobró Complex of the Pernambuco-Alagoas Terrane (Cruz et al, 2014), also indicating inheritance of exhumed Stenian-Tonian crust.…”

Geochemical and detrital zircon geochronological investigation of the metavolcanosedimentary Araticum complex, sergipano fold belt: Implications for the evolution of the Borborema Province, NE Brazil

“…Brazil-Africa correlation has a major role in paleogeographic reconstructions of Western Gondwana, as shown by several studies (Caby, 1989;Castaing et al, 1993;Toteu et al, 2001;Brito Neves et al, 2002;Van Schmus et al, 2008). Recent lithotectonic connections between the Neoproterozoic Borborema Province in NE Brazil with West Africa domains, such as Trans-Saharan, Nigerian and Oubanguides mobile belts were focused on the oceanic paleobasins and proto-oceans (Van Schmus et al, 2008;Caxito et al, 2012Caxito et al, , 2014Alcântara et al, 2017).…”