Age, composition, and source of continental arc- and syn-collision granites of the Neoproterozoic Sergipano Belt, Southern Borborema Province, Brazil

Author(s)

Oliveira, Elson P. ; Bueno, Juliana F. ; McNaughton, Neal J. ; Silva Filho, Adejardo F. ; Nascimento, Rosemery S. ; Donatti-Filho, Jose P.

• Document type: Journal article
• Source: Journal of South American Earth Sciences; v. 58, p. 24-pg., 2015-03-01.

Abstract

The Sergipano belt is the outcome of collision between the Pernambuco-Alagoas Domain (Massif) and the Sao Francisco Craton during Neoproterozoic assembly of West Gondwana. Although the understanding of the Sergipano belt evolution has improved significantly, the timing of emplacement, geochemistry and tectonic setting of granitic bodies in the belt is poorly known. We recognized two granite age groups: 630-618 Ma granites in the Canincle, Pogo Redondo and Macurure domains, and 590-570 Ma granites in the Macurure metasedimentary domain. U Pb SHRIMP zircon ages for granites of first age group indicated ages of 631 +/- 4 Ma for the Sitios Novos granite, 623 +/- 7 Ma for the Pogo Redondo granite, 619 +/- 3.3 Ma for the Lajedinho monzodiorite, and 618 +/- 3 Ma for the Queimada Grande granodiorite. These granitoids are dominantly high-K calc-alkaline, magnesian, metaluminous, mafic enclave-rich (Queimada Grande and Lajedinho), or with abundant inherited zircon grains (Pogo Redondo and Sitios Novos). Geochemical and isotope data allow us to propose that Sitios Novas and Pogo Redondo granites are product of partial melting of Pogo Redondo migmatites. Sr-Nd isotopes of the Queimada Grande granodiorite and Lajedinho monzodiorite suggest that their parental magma may have originated by mixing between a juvenile mafic source and a crustal component that could be the Pogo Redondo migmatites or the Macurure metasediments. Other 630-618 Ma granites in the belt are the mafic enclave-rich Coronel Joao S granodiorite and the Camara tonalite in the Macurure sedimentary domain. These granites have similar geochemical and isotopic characteristics as the Lajedinho and Queimada Grande granitoids. We infer for the Camara tonalite and Coronel Joao S granodiorite that their parental magmas have had contributions from mafic lower crust and felsic upper crust, most probably from underthrust Sao Francisco Craton, or Pernambuco-Alagoas Domain. The younger 590-570 Ma granite group is confined to the Macurure metasedimentary domain. Although these granites do not show typical features of S-type granites, their U Pb age, field relationships, geochemical and Sr-Nd data suggest that their parental magmas have originated from high degree melting of the Macurure micaschists. Field observations support a model in which the Macurure domain, limited by the Belo MonteJeremoabo and Sao Miguel do Aleixo shear zones, behaved as a ductile channel flow for magma migration and emplacement during the Neoproterozoic, very much like the channel flow model proposed for emplacement of leucogranites in the Himalayas. (C) 2014 Elsevier Ltd. All rights reserved. (AU)