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.

The tectonic evolution of the Neoproterozoic Brasília Belt, central Brazil: a geochronological and isotopic approach

“…The Brasília Belt (from Dardenne 2000, Pimentel et al 2000b, Valeriano et al 2004. Giustina et al 2009a, Cordeiro et al 2014, the Silvânia Volcano-Sedimentary Sequence (2.12 Ga) and the Jurubatuba granite (2.09 Ga) , which are pointed out in Fig. 2.…”

The Paleoproterozoic in the South-American continent: Diversity in the geologic time

“…One may also include in this context the western portion of Bahia State (Western Mobile Belt of Bahia, part of the São Francisco Craton) and part of eastern Goiás (" Dianópolis e Silvânia" Belt), which present several discontinuous Rhyacian basement windows, underneath Proterozoic and Phanerozoic covers. An additional example of these Rhyacian events and mobile belts is recorded in some the large "massifs", such as the Goiás Central Massif (clustering granite-greenstone terrains), Pernambuco-Alagoas, and São José do Campestre, to be commented (See Delgado et al, 2003;Dantas et al, 2008;Della Giustina et al, 2008).…”

“…There is the record of meta-volcano-sedimentary sequence, crosscut by granites, which is worth mentioning. The "Campinorte Sequence" (exposed due to the erosion of the Serra da Mesa) is composed of metapsammites and metapelites (being quartz-micaschists the most common rocks), with gondite and metachert lenses (Della Giustina et al, 2008) and subordinate meta-rhyolites and pyroclastic rocks. Ortho derived metamorphic rocks (tonalites and granodiorites) are intrusive into this sequence, and they yield UePb ages of 2.18e2.16 Ga. SmeNd determinations lead to positive or slightly negative eNd values, indicating the juvenile nature of these rocks, that were strongly reworked by Brasiliano events.…”

The Paleoproterozoic Campinorte Arc: Tectonic evolution of a Central Brazil pre-Columbia orogeny

“…Geochronological evidence of a Paleoproterozoic accretionary event is preserved in the Goiás Massif Campinorte Sequence containing ∼2.17-2.05 Ga magmtic arc rocks and correlated sedimentary sequences (Kuyumjian et al, 2004;Giustina et al, 2009a), in spite of pervasive regional Neoproterozoic metamorphic and structural overprint. The occurrence of high temperature granulites within the northern Brasília Belt basement is in tandem with coeval arcs in neighboring São Francisco and Amazonian cratons (Rosa-Costa et al, 2006;Oliveira et al, 2011).…”