Maria Emilia Schutesky Della Giustina

U-Pb and Sm-Nd constraints on the nature of the Campinorte sequence and related Palaeoproterozoic juvenile orthogneisses, Tocantins Province, central Brazil

Abstract The Palaeoproterozoic era was the most important stage of crustal accretion in the South American Platform, being responsible for the development of several magmatic arcs, which represent approximately 35% of the present-day continental crust. The recently mapped Campinorte volcano-sedimentary sequence and associated plutonic rocks represent this Palaeoproterozoic history in the northern Brasilia Belt, central Brazil. The sequence consists of metapsammites and metapelites, with interbedded lenses of gondites and metacherts, as well as rhyolite and pyroclastic deposits. Tonalite, granodiorite and granite crystallized between c. 2.18 and 2.16 Ga, as indicated by U–Pb zircon analyses. Sm–Nd TDM model ages range between c. 2.1 and 2.7 Ga, with ϵNd values ranging from −2.14 to +3.36, indicating the dominantly juvenile nature of the original magmas. A LA-ICPMS provenance study of zircon grains from a quartzite sample reveals a single sediment source with Palaeoproterozoic age. The data presented here provide new information on the Palaeoproterozoic juvenile crust of central Brazil and suggest correlation with other Palaeoproterozoic provinces, especially the Birimian Belt in West African Craton and those of the Guiana Shield, thus contributing to reconstruction of the Columbia supercontinent.