Advanced

First precise U-Pb baddeleyite ages of 1500 Ma mafic dykes from the Sao Francisco Craton, Brazil, and tectonic implications

Silveira, E. M. ; Söderlund, Ulf LU ; Oliveira, E. P. ; Ernst, R. E. and Menezes Leal, A. B. (2013) In Lithos 174. p.144-156
Abstract
The Sao Francisco Craton (SFC) is an Archaean-Proterozoic craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few poor precision Rb-Sr and Sm-Nd isochrons. Here, dykes from the Curaca belt, in the northeastern portion of the craton, as well as from the Chapada Diamantina region in the central part, were dated using U-Pb on baddeleyite (ID-TIMS). These dykes yielded similar baddeleyite U-Pb ages of 1506.7 +/- 6.9 Ma (Curaca) and 1501.0 +/- 9.1 Ma (Chapada), with converging trends indicating a possible magmatic centre located near the western margin of the Sao Francisco Craton. The two dyke swarms are subalkaline, and have light rare earth enriched... (More)
The Sao Francisco Craton (SFC) is an Archaean-Proterozoic craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few poor precision Rb-Sr and Sm-Nd isochrons. Here, dykes from the Curaca belt, in the northeastern portion of the craton, as well as from the Chapada Diamantina region in the central part, were dated using U-Pb on baddeleyite (ID-TIMS). These dykes yielded similar baddeleyite U-Pb ages of 1506.7 +/- 6.9 Ma (Curaca) and 1501.0 +/- 9.1 Ma (Chapada), with converging trends indicating a possible magmatic centre located near the western margin of the Sao Francisco Craton. The two dyke swarms are subalkaline, and have light rare earth enriched chondrite-normalized patterns but the Curaca dykes have lower Mg-number and higher abundances of most incompatible trace elements than the Chapada dykes. Geochemical modelling and trace element ratios suggest that the two dyke swarms had different petrogenesis, with the Chapada dykes being derived from more depleted mantle sources and the Curaca dykes from enriched sources, however the mantle sources of both dyke swarms appear to have had contributions from an enriched plume. Current geochronological and palaeomagnetic data suggest a coherent Sao Francisco-Congo block from at least the late Mesoproterozoic until the opening of the South Atlantic (ca. 130 Ma ago). The discovery of ca. 1500 Ma intrusions in the Sao Francisco Craton is a major step forward to a more complete barcode record for the SFC-Congo Craton, which can be used in future palaeo-continental reconstructions. (C) 2012 Elsevier B.V. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Sao Francisco-Congo Cratons, Mafic intrusions, U-Pb baddeleyite, Geochronology, Geochemistry
in
Lithos
volume
174
pages
144 - 156
publisher
Elsevier
external identifiers
  • wos:000321680400012
  • scopus:84878908431
ISSN
0024-4937
DOI
10.1016/j.lithos.2012.06.004
language
English
LU publication?
yes
id
48010314-20a5-47c8-81af-6ae56f55a328 (old id 3975633)
date added to LUP
2016-04-01 10:59:43
date last changed
2020-12-08 05:09:24
@article{48010314-20a5-47c8-81af-6ae56f55a328,
  abstract     = {The Sao Francisco Craton (SFC) is an Archaean-Proterozoic craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few poor precision Rb-Sr and Sm-Nd isochrons. Here, dykes from the Curaca belt, in the northeastern portion of the craton, as well as from the Chapada Diamantina region in the central part, were dated using U-Pb on baddeleyite (ID-TIMS). These dykes yielded similar baddeleyite U-Pb ages of 1506.7 +/- 6.9 Ma (Curaca) and 1501.0 +/- 9.1 Ma (Chapada), with converging trends indicating a possible magmatic centre located near the western margin of the Sao Francisco Craton. The two dyke swarms are subalkaline, and have light rare earth enriched chondrite-normalized patterns but the Curaca dykes have lower Mg-number and higher abundances of most incompatible trace elements than the Chapada dykes. Geochemical modelling and trace element ratios suggest that the two dyke swarms had different petrogenesis, with the Chapada dykes being derived from more depleted mantle sources and the Curaca dykes from enriched sources, however the mantle sources of both dyke swarms appear to have had contributions from an enriched plume. Current geochronological and palaeomagnetic data suggest a coherent Sao Francisco-Congo block from at least the late Mesoproterozoic until the opening of the South Atlantic (ca. 130 Ma ago). The discovery of ca. 1500 Ma intrusions in the Sao Francisco Craton is a major step forward to a more complete barcode record for the SFC-Congo Craton, which can be used in future palaeo-continental reconstructions. (C) 2012 Elsevier B.V. All rights reserved.},
  author       = {Silveira, E. M. and Söderlund, Ulf and Oliveira, E. P. and Ernst, R. E. and Menezes Leal, A. B.},
  issn         = {0024-4937},
  language     = {eng},
  pages        = {144--156},
  publisher    = {Elsevier},
  series       = {Lithos},
  title        = {First precise U-Pb baddeleyite ages of 1500 Ma mafic dykes from the Sao Francisco Craton, Brazil, and tectonic implications},
  url          = {http://dx.doi.org/10.1016/j.lithos.2012.06.004},
  doi          = {10.1016/j.lithos.2012.06.004},
  volume       = {174},
  year         = {2013},
}