Archean–Ediacaran evolution of the Campos Gerais Domain — A reworked margin of the São Francisco paleocontinent (SE Brazil): Constraints from metamafic–ultramafic rocks

• Published in: Di xue qian yuan. 2022-09, Vol.13 (5), p.101201, Article 101201
• Main Authors: Pinheiro, Marco Aurélio Piacentini, Guice, George L., Magalhães, Joana Reis
• Format: Article
• Language: English
• Subjects: Archean geodynamics; Belts; Constraints; Correlation; Crystallization; Domains; Evolution; Geochemistry; Geochronology; Gondwana; Grains; Isotopes; Komatiites; Orogeny; Petrography; Radiometric dating; Rhyacian orogeny; Sedimentary rocks; Segments; Southern Brasília Orogen; São Francisco Craton; Ultramafic materials; Zircon
• ISSN: 1674-9871; 2588-9192
• DOI: 10.1016/j.gsf.2021.101201

[Display omitted] •Campos Gerais Domain: Archean–Ediacaran segment of the São Francisco paleocontinent.•New Mesoarchean (2.9 Ga) mafic magmatism is identified in the Campos Gerais Complex.•First Rhyacian (2.1 Ga) arc-related ultramafic rocks is recognized.•Metaultramafites register metamorphic overprint at 590 Ma. The Campos Gerais Domain (CGD) in southeastern Brazil is an approximately 180 km × 35 km area of Archean–Proterozoic rocks located southwest of the São Francisco Craton (SFC). The Archean–Paleoproterozoic evolution of the CGD — alongside its potential correlation with the SFC or other cratonic blocks in the region — is currently poorly-constrained. We present the results of systematic petrography, bulk-rock geochemistry, mineral chemistry and geochronology for a suite of scarcely studied mafic–ultramafic rocks from the CGD. We also provide a compilation of previously reported bulk-rock geochemical and spinel group mineral chemical data for mafic–ultramafic rocks throughout the CGD, and geochronological information for various lithotypes in the region. The CGD records a protracted Mesoarchean to Statherian (3.1–1.7 Ga) crustal evolution, which we interpret to share a common history with the southern SFC and their related reworked segments, suggesting that it is a westward extension of this cratonic terrain. The metavolcano-sedimentary rocks of the Fortaleza de Minas and Alpinópolis segments represent a Mesoarchean greenstone belt that is stratigraphically and chemically comparable to Archean greenstone belts worldwide, and that is broadly coeval with a local suite of tonalite-trondhjemite-granodiorite (TTG) gneisses and migmatites. U-Pb SHRIMP zircon data from a subalkaline metagabbro yielded a concordia age of ca. 2.96 Ga, revealing a previously unrecognized phase of Archean magmatism in the CGD that can be chrono-correlated with metakomatiite and TTG generation elsewhere in the São Francisco paleocontinent. Our data contradict a hypothesis whereby the metavolcano-sedimentary rocks of the Jacuí-Bom Jesus da Penha and Petúnia segments represent an ophiolite, as previously suggested, instead presenting features that point to formation in association with a continental arc. Coupled with a U-Pb (SHRIMP) crystallization age of ca. 2.13 Ga recorded by zircon grains from a metaultramafic rock, these data highlight that a magmatic event was chrono-correlated with the main accretionary phase of the Minas Orogeny, and with the Pouso Alegre/Amparo and São V