Neoproterozoic oceanic crust remnants in northeast Brazil

Abstract

Research Article| May 01, 2014 Neoproterozoic oceanic crust remnants in northeast Brazil Fabrício Caxito; Fabrício Caxito 1Instituto de Geociências, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil2Geotop, Université du Québec à Montréal, Montréal H3C 3P8, Canada Search for other works by this author on: GSW Google Scholar Alexandre Uhlein; Alexandre Uhlein 1Instituto de Geociências, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil Search for other works by this author on: GSW Google Scholar Ross Stevenson; Ross Stevenson 2Geotop, Université du Québec à Montréal, Montréal H3C 3P8, Canada Search for other works by this author on: GSW Google Scholar Gabriel J. Uhlein Gabriel J. Uhlein 1Instituto de Geociências, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil Search for other works by this author on: GSW Google Scholar Geology (2014) 42 (5): 387–390. https://doi.org/10.1130/G35479.1 Article history received: 16 Jan 2014 rev-recd: 27 Feb 2014 accepted: 05 Mar 2014 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Fabrício Caxito, Alexandre Uhlein, Ross Stevenson, Gabriel J. Uhlein; Neoproterozoic oceanic crust remnants in northeast Brazil. Geology 2014;; 42 (5): 387–390. doi: https://doi.org/10.1130/G35479.1 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 SocietyGeology Search Advanced Search Abstract The Borborema Province of northeast Brazil occupies a strategic position in the central portion of West Gondwana, linking three of its major cratonic constituents: the São Francisco–Congo, Amazon, and West Africa cratons. The southern portion of the province, the Riacho do Pontal fold belt, comprises an association of exhalative rocks with metabasalts having transitional mid-oceanic ridge basalt geochemistry (Monte Orebe Complex) that suggests the preservation of remnants of Neoproterozoic oceanic crust. This view is supported by geophysical data: the Riacho do Pontal fold belt corresponds to the inflexion of a paired positive-negative Bouguer anomaly similar to other Precambrian suture zones. Sm-Nd isotope data for the metabasalts yield a whole-rock isochron age of 819 ± 120 Ma with an initial εNd(t) = +4.4, indicating derivation from a depleted mantle source. The onset of subduction within the Borborema Province (ca. 630 Ma) caused the inversion of basins and obduction of slices of oceanic crust. In this scenario, the Riacho do Pontal fold belt represents a complete late Neoproterozoic plate tectonics cycle involving the collision of the São Francisco craton (lower plate) with the Pernambuco-Alagoas block (upper plate). This interpretation challenges current views that the Borborema Province has acted as a coherent block since Paleoproterozoic time (part of the Atlantica supercontinent), suggesting instead a dynamic setting, where multiple plates interacted during the Proterozoic. The Monte Orebe ophiolite provides a link with other Cryogenian oceanic crust occurrences in central Brazil and West Africa, indicating the preservation of a transcontinental Neoproterozoic suture zone in the heart of West Gondwana. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.