High-K granites between the Archean Gaviao and Jequie blocks, Sao Francisco Craton, Brazil: Implications for cratonization and amalgamation of the Rhyacian Atlantica continent

Autor(es)

Zincone, Stefano A. ^[1] ; Oliveira, Elson P. ^[2] ; Ribeiro, Bruno P. ^[3] ; Marinho, Moacyr M. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Fed Ouro Preto, Dept Geol, Escola Minas, BR-35400000 Ouro Preto, MG - Brazil

^[2] Univ Estadual Campinas, Inst Geosci, Dept Geol & Nat Resources, POB 6152, BR-13083970 Campinas - Brazil

^[3] CBPM Co Baiana Pesquisa Mineral, Ctr Adm, Quarta Ave 460, BR-41745002 Salvador, BA - Brazil

^[4] Univ Fed Bahia, Dept Geol, Rua Barao de Geremoabo S-N, BR-40170209 Salvador, BA - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of South American Earth Sciences; v. 105, JAN 2021.
• Citações Web of Science: 0

Resumo

Precambrian terrane boundaries are sites of diverse rock associations and structural complexity. Motions along the boundary zones are commonly related to the construction of ancient large continental masses. This seems to be the case in the Sao Francisco Craton, Brazil, where three major blocks (Gaviao, Jequie and Serrinha) collided in the Paleoproterozoic to form the northern part of the craton. This manuscript presents zircon U-Pb ages and whole-rock geochemistry for rock associations on the western border of the Jequie ` Block, which is defined by the north-trending left-lateral 600-km long Contendas-Jacobina fault zone. The studied rocks are granulite to amphibolite facies Neoarchean orthopyroxene-hornblende granite gneisses of the Jequie ` block, which also occur tectonically imbricated within Paleoproterozoic metavolcanosedimentary rocks of the Contendas-Mirante belt. The rocks are 2.65-2.63 Ga high-K ferroan, metaluminous to slightly peraluminous syeno-monzogranite in composition, with negative epsilon Nd-(2650) and Nd model ages of 3.05-2.88 Ga. They are depleted in Sr and Ti, enriched in Th, Ba and Pb enrichment, and have marked negative Eu/Eu{*}. This geochemical signature coupled with the Nd-isotope data indicate that the parental granitic magma was generated by crustal reworking of felsic Mesoarchean crust distinct from the western-sitting >3.3 Ga Gaviao Block. The investigated granitic gneisses are similar to other potassic granitoids that occur in the Sao Francisco Craton, which mark the thermal stabilization of the Archean lithosphere. The westward thrusting of the Neoarchean hornblende granitic gneiss and associated high-Mg tremolitite (meta-basalts) onto Paleoproterozoic volcano-sedimentary sequences establishes field evidence of Paleoproterozoic nappe stacking before lateral displacement during block collision. The crustal amalgamation is related to the assembly of the Sao Francisco-Congo Craton, a major landmass established before the Columbia supercontinent. (AU)

• Processo FAPESP: 12/15824-6 - Evolução de terrenos arqueanos do Cráton São Francisco e Província Borborema: implicações para processos geodinâmicos e paleoambientais globais
• Beneficiário: Elson Paiva de Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Temático