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U-Pb ages and geochemistry of mafic dyke swarms from the Uaua Block, Sao Francisco Craton, Brazil: LIPs remnants relevant for Late Archaean break-up of a supercraton

Oliveira, E. P. ; Silveira, E. M. ; Söderlund, Ulf LU and Ernst, R. E. (2013) In Lithos 174. p.308-322
Abstract
The Sao Francisco Craton (SFC) is an Archaean craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few dates of poor precision. Here, two dyke swarms from the Uaua Block in the northeastern portion of the craton were dated using U-Pb on baddeleyite (ID-TIMS) and zircon (SIMS). The older dyke swarm trends mainly N-S to NW-SE (but also NE) and comprises norite dykes, whereas the younger dykes are tholeiite and trend NE-SW. The ages of 2726.2 +/- 3.2 and 2623.8 +/- 7.0 Ma date dykes of noritic and tholeiitic compositions, respectively. The older age matches the ages of several Archaean-Large Igneous Provinces (tholeiitic-komatiite greenstone belts and... (More)
The Sao Francisco Craton (SFC) is an Archaean craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few dates of poor precision. Here, two dyke swarms from the Uaua Block in the northeastern portion of the craton were dated using U-Pb on baddeleyite (ID-TIMS) and zircon (SIMS). The older dyke swarm trends mainly N-S to NW-SE (but also NE) and comprises norite dykes, whereas the younger dykes are tholeiite and trend NE-SW. The ages of 2726.2 +/- 3.2 and 2623.8 +/- 7.0 Ma date dykes of noritic and tholeiitic compositions, respectively. The older age matches the ages of several Archaean-Large Igneous Provinces (tholeiitic-komatiite greenstone belts and continental flood basalts) worldwide and represents part of a feeder system, but the younger age is similar to Andean style continental margin magmatism in the Sao Francisco and Zimbabwe cratons. The two dyke swarms are tholeiitic in composition but the noritic dykes are more enriched in both compatible and incompatible elements and have higher (La/Yb)(N) ratios than the tholeiite dykes. The norite dykes are interpreted as low degrees of melting from enriched refractory mantle sources, whereas the tholeiite dykes represent high degrees of partial melting of more depleted mantle sources; the two mafic dyke swarms may be related to each other by progressive extension of the continental lithosphere. It is suggested that the Uaua Block with its dyke swarms is a small piece of Archaean crust dispersed after the break-up of a major Archaean supercraton. (C) 2012 Elsevier B.V. All rights reserved. (Less)
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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Sao Francisco Craton, Mafic intrusions, U-Pb baddeleyite and zircon, Geochronology, Geochemistry
in
Lithos
volume
174
pages
308 - 322
publisher
Elsevier
external identifiers
  • wos:000321680400021
  • scopus:84878933197
ISSN
0024-4937
DOI
10.1016/j.lithos.2012.05.025
language
English
LU publication?
yes
id
9c8b836e-b31a-4c3c-b28b-929116564826 (old id 3975664)
date added to LUP
2016-04-01 11:01:10
date last changed
2020-12-27 06:01:40
@article{9c8b836e-b31a-4c3c-b28b-929116564826,
  abstract     = {The Sao Francisco Craton (SFC) is an Archaean craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few dates of poor precision. Here, two dyke swarms from the Uaua Block in the northeastern portion of the craton were dated using U-Pb on baddeleyite (ID-TIMS) and zircon (SIMS). The older dyke swarm trends mainly N-S to NW-SE (but also NE) and comprises norite dykes, whereas the younger dykes are tholeiite and trend NE-SW. The ages of 2726.2 +/- 3.2 and 2623.8 +/- 7.0 Ma date dykes of noritic and tholeiitic compositions, respectively. The older age matches the ages of several Archaean-Large Igneous Provinces (tholeiitic-komatiite greenstone belts and continental flood basalts) worldwide and represents part of a feeder system, but the younger age is similar to Andean style continental margin magmatism in the Sao Francisco and Zimbabwe cratons. The two dyke swarms are tholeiitic in composition but the noritic dykes are more enriched in both compatible and incompatible elements and have higher (La/Yb)(N) ratios than the tholeiite dykes. The norite dykes are interpreted as low degrees of melting from enriched refractory mantle sources, whereas the tholeiite dykes represent high degrees of partial melting of more depleted mantle sources; the two mafic dyke swarms may be related to each other by progressive extension of the continental lithosphere. It is suggested that the Uaua Block with its dyke swarms is a small piece of Archaean crust dispersed after the break-up of a major Archaean supercraton. (C) 2012 Elsevier B.V. All rights reserved.},
  author       = {Oliveira, E. P. and Silveira, E. M. and Söderlund, Ulf and Ernst, R. E.},
  issn         = {0024-4937},
  language     = {eng},
  pages        = {308--322},
  publisher    = {Elsevier},
  series       = {Lithos},
  title        = {U-Pb ages and geochemistry of mafic dyke swarms from the Uaua Block, Sao Francisco Craton, Brazil: LIPs remnants relevant for Late Archaean break-up of a supercraton},
  url          = {http://dx.doi.org/10.1016/j.lithos.2012.05.025},
  doi          = {10.1016/j.lithos.2012.05.025},
  volume       = {174},
  year         = {2013},
}