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A new interpretation on the Sergipano belt domain

A NEW INTERPRETATION ON THE SERGIPANO BELT DOMAIN

MARINHO A. SILVA-FILHO AND HELTON H. F. TORRES

Companhia de Pesquisa de Recursos Minerais (CPRM), Recife, PE, Brazil.

Presented by ALCIDES N. SIAL

This study deals with newly identified tectonic-stratigraphic domains in the Sergipano and Sul-Alagoano belts of the Borborema Province, northeastern Brazil. In the first belt, besides the well-known domains of Macururé, Vaza Barris and Estância, two others are recognized: Rio Coruripe and Viçosa. The Rio Coruripe domain contains rift-related volcano-sedimentary sequence, metabasalts and iron-formation bearing, intruded by mafic-ultramafic layered complex. The Viçosa domain consists of a metamorphosed volcano-sedimentary sequence; Mesoproterozoic plutonic rocks with 1.57Ga (U-Pb) and 1.0Ga (Rb-Sr) and Neoproterozoic peraluminous granitoids with 0.75Ga (Rb-Sr) and calc-alkaline granites with 0.59Ga (U-Pb). Carbonates from the Olhos d'Água Fm. of the Vaza Barris domain have an isotopic signature similar to that of the Bambuí group, distinct of the Jacoca carbonates (Miaba group). The Palestina Fm., at the base of the Olhos d'Água Fm., encloses Miaba group deformed pebbles. The last one, chronocorrelated to the Macururé group, is Mesoproterozoic in age. The Sul-Alagoano belt has two domains. The Canindé-Marancó domain hosts flysch-type volcanoclastic sedimentation; calc-alkaline volcanic rocks with 1.04Ga (U-Pb; TDM=1.2Ga); tonalitic (TDM=1.75Ga) and peraluminous (TDM=1.66Ga) Mesoproterozoic plutonic rocks; early peraluminous Neoproterozoic plutonic rocks (U-Pb; 0,715Ga); podiform chromite-bearing ultrabasic rocks that could be mantle-derived ophiolitic slices. The Pernambuco-Alagoas domain shows a characteristic tonalitic-dominant Mesoproterozoic plutonism (TDM=1.3Ga); fracture-bound late shoshonitic/peralkaline and peraluminous magmatism (0.58Ga, Rb-Sr and TDM=1.0Ga).

The Sergipano belt has rift-related and Atlantic margin Meso/Neoproterozoic platform sedimentation. Basement nucleus (TDM=3.0Ga), granitoids from the Macururé domain with model ages between 1.71 and 1.3Ga and from Viçosa domain between 0.9 and 2.5Ga, suggest a sialic basement. The Marancó/Canindé calc-alkaline volcanics and ophiolites (?) point to the presence of oceanic crust in the Sul-Alagoano belt. Abundant Mesoproterozoic tonalites resemble a thickened Andean-type arc in the Pernambuco/Alagoas domain, with extensional shoshonitic/peralkaline magmatism (0.58Ga, Rb-Sr). There were two stages of amalgamation in the Sergipano and Sul-Alagoano belts: at 1.0 and at 0.75Ga, characterized, respectively, by Caririano- and Brasiliano age peraluminous granitoids. The sutures between belts and their domains are bounded, respectively, by the Belo Monte/Jeremoabo shear zone and granites, both showing remarkable magnetic anomalies. — (May 24, 2002) .

Publication Dates

  • Publication in this collection
    09 Oct 2002
  • Date of issue
    Sept 2002
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