The 2.26 to 2.18 Ga Arc-Related Magmatism of the Almas-Conceição do Tocantins Domain: An Early Stage of the São Francisco Paleocontinent Assembly in Central Brazil

Abstract

Paleoproterozoic (Rhyacian) rocks dominate within the basement of the Neoproterozoic Brasília Belt and their genesis has been attributed to the orogenic amalgamation event that assembled the São Francisco-Congo paleocontinent from 2.18 to 2.07 Ga. However, the tectonic framework and genesis of the building blocks involved in this continent-wide amalgamation event are unclear, particularly in relation to terranes from the Almas-Conceição do Tocantins Domain, in the Goiás Massif, central Brazil. This work provides new whole-rock chemical and geochronological data, which indicate the generation of felsic to intermediate magmatism around 2.29 and 2.28 Ga corresponding to the Monzogranitic Unit and the Quartz-dioritic Suite, respectively. Later magmatic events occurred in a continental arc setting, around 2.26 to 2.2 Ga represented by metaluminous to peraluminous I-type magmatism of the Granodioritic to Tonalitic Suite (GTS) and the Serra do Boqueirão Suite. Around 2.2 to 2.18 Ga a peraluminous I-type magmatism took place and generated the Peraluminous Suite (PS). Our data show that after an earlier Siderian magmatic event around 2.45–2.34 Ga, reported in previous works, the Almas do Conceição do Tocantins Domain oversaw additional Rhyacian events of magmatic activity around 2.29 Ga to 2.18 Ga. Regional geotectonic correlations with the São Francisco Craton and other pericratonic belts indicate coeval magmatic events taking place during the early stages of the Columbia Supercontinent amalgamation.