U-Pb Geochronology of Archean magmatism and Proterozoic metamorphism in the Quadrilátero Ferrífero, southern São Francisco craton, Brazil

Abstract

Research Article| September 01, 1992 U-Pb Geochronology of Archean magmatism and Proterozoic metamorphism in the Quadrilátero Ferrífero, southern São Francisco craton, Brazil N. MACHADO; N. MACHADO 1Department of Geology, Royal Ontario Museum, Toronto, Ontario M5S 2C6, Canada Search for other works by this author on: GSW Google Scholar C. M. NOCE; C. M. NOCE 2Departamento de Geologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil Search for other works by this author on: GSW Google Scholar E. A. LADEIRA; E. A. LADEIRA 2Departamento de Geologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil Search for other works by this author on: GSW Google Scholar O. BELO DE OLIVEIRA O. BELO DE OLIVEIRA 3Rio Doce Geologia e Mineração (DOCEGEO), Belo Horizonte, Minas Gerais, Brazil Search for other works by this author on: GSW Google Scholar Author and Article Information N. MACHADO 1Department of Geology, Royal Ontario Museum, Toronto, Ontario M5S 2C6, Canada C. M. NOCE 2Departamento de Geologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil E. A. LADEIRA 2Departamento de Geologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil O. BELO DE OLIVEIRA 3Rio Doce Geologia e Mineração (DOCEGEO), Belo Horizonte, Minas Gerais, Brazil Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1992) 104 (9): 1221–1227. https://doi.org/10.1130/0016-7606(1992)104<1221:UPGOAM>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation N. MACHADO, C. M. NOCE, E. A. LADEIRA, O. BELO DE OLIVEIRA; U-Pb Geochronology of Archean magmatism and Proterozoic metamorphism in the Quadrilátero Ferrífero, southern São Francisco craton, Brazil. GSA Bulletin 1992;; 104 (9): 1221–1227. doi: https://doi.org/10.1130/0016-7606(1992)104<1221:UPGOAM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Quadrilátero Ferrífero is a metallogenic district (Au, Fe, Mn) located in the southernmost São Francisco craton in eastern Brazil. It is composed of Archean granitoids, gneisses, and a greenstone belt sequence (Rio das Velhas Supergroup), overlain by a Proterozoic clastic-chemical sedimentary sequence hosting a thick Lake Superior-type banded iron formation (Minas Supergroup). A U-Pb study of the main units leads to the following conclusions: granitoid emplacement was dated at 2776 +7/-6 Ma and 2721 ± 3 Ma; two felsic volcanic rocks from the Rio das Velhas Supergroup yielded ages of 2776 +23/-10 Ma and 2772 ± 6 Ma. These data indicate that greenstone-belt volcanism was coeval with granitoid emplacement, a common feature of greenstone-belt terrains, but so far undocumented in the southern São Francisco shield. The younger granitoid intrusion marks the stabilization of the shield in Late Archean time. Zircon cores older than 2776 Ma, together with other data, indicate the presence of continental crust 2.88-3.1 Ga old in the Quadrilátero Ferrífero. A detrital zircon from the uppermost formation in the Minas Supergroup (Sabará Formation) is concordant at 2125 ± 4 Ma and provides the first age constraint on the deposition of the Supergroup. Monazite from two pegmatites and titanite from an amphibolite enclave in gneisses from the Bação Complex, in central Quadrilátero Ferrífero, yielded ages between 2060 Ma and 2030 Ma. These data may constrain the minimum age for the deposition of the Minas Supergroup. In addition, they indicate that the Early Proterozoic Transamazomian orogeny is represented by amphibolite-facies metamorphism and partial melting of Archean crust. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.