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The Greater Cederberg−False Bay Large Igneous Province in South Africa : A southern node of widespread magmatism associated with South Atlantic rifting

Kingsbury, C. G. ; Altermann, W. ; Kramers, J. ; Ernst, R. E. ; Söderlund, U. LU and Klausen, M. B. (2023) In South African Journal of Geology 126(4). p.471-484
Abstract

A new 130 to 140 Ma mafic dyke swarm, is identified in western South Africa. It consists of the previously undated Cederberg dyke swarm (CDS), for which we report U-Pb ID-TIMS baddeleyite ages of 131.4 ± 4.5 Ma (Knersvlake subswarm) and 133.0 ± 1.5 Ma (Doring-Tanqua subswarm).40Ar/39Ar dates on these two samples and two additional dates of the Doring – Tanqua subswarm cluster between 128.5 ± 1.4 Ma and 132.2 ± 1.5 Ma. We also report40Ar/39Ar ages of 139.3 ± 3.5 Ma for an east-west trending dyke located further north: 27 km south of Kleinsee, and 140.3 ± 1.2 Ma for an east-west dyke near Garies. Together, these eight ages robustly date the emplacement of the northern part of a Greater... (More)

A new 130 to 140 Ma mafic dyke swarm, is identified in western South Africa. It consists of the previously undated Cederberg dyke swarm (CDS), for which we report U-Pb ID-TIMS baddeleyite ages of 131.4 ± 4.5 Ma (Knersvlake subswarm) and 133.0 ± 1.5 Ma (Doring-Tanqua subswarm).40Ar/39Ar dates on these two samples and two additional dates of the Doring – Tanqua subswarm cluster between 128.5 ± 1.4 Ma and 132.2 ± 1.5 Ma. We also report40Ar/39Ar ages of 139.3 ± 3.5 Ma for an east-west trending dyke located further north: 27 km south of Kleinsee, and 140.3 ± 1.2 Ma for an east-west dyke near Garies. Together, these eight ages robustly date the emplacement of the northern part of a Greater Cederberg-False Bay Dyke Swarm (GCFDS) at ca. 130 to 140 Ma. Trace and rare earth element data reported herein suggest these dykes are compositionally E-MORB basalts that underwent modification either via subduction-modified lithospheric mantle, or by continental crust, or a combination thereof, and are petrogenetically similar to the ca. 132 Ma False Bay dykes around Cape Town. Therefore, we propose to unify all these coeval and compositionally similar dykes into one large igneous province (LIP) termed the Greater Cederberg-False Bay Large Igneous Province (GCF-LIP).

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
South African Journal of Geology
volume
126
issue
4
pages
14 pages
publisher
Geological Society of South Africa
external identifiers
  • scopus:85180705130
ISSN
1012-0750
DOI
10.25131/sajg.126.0023
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2023 Geological Society of South Africa. All rights reserved.
id
ce54ffa3-df80-4cc6-8199-69fd5c8a77a0
date added to LUP
2024-10-16 10:05:22
date last changed
2025-04-04 14:03:24
@article{ce54ffa3-df80-4cc6-8199-69fd5c8a77a0,
  abstract     = {{<p>A new 130 to 140 Ma mafic dyke swarm, is identified in western South Africa. It consists of the previously undated Cederberg dyke swarm (CDS), for which we report U-Pb ID-TIMS baddeleyite ages of 131.4 ± 4.5 Ma (Knersvlake subswarm) and 133.0 ± 1.5 Ma (Doring-Tanqua subswarm).<sup>40</sup>Ar/<sup>39</sup>Ar dates on these two samples and two additional dates of the Doring – Tanqua subswarm cluster between 128.5 ± 1.4 Ma and 132.2 ± 1.5 Ma. We also report<sup>40</sup>Ar/<sup>39</sup>Ar ages of 139.3 ± 3.5 Ma for an east-west trending dyke located further north: 27 km south of Kleinsee, and 140.3 ± 1.2 Ma for an east-west dyke near Garies. Together, these eight ages robustly date the emplacement of the northern part of a Greater Cederberg-False Bay Dyke Swarm (GCFDS) at ca. 130 to 140 Ma. Trace and rare earth element data reported herein suggest these dykes are compositionally E-MORB basalts that underwent modification either via subduction-modified lithospheric mantle, or by continental crust, or a combination thereof, and are petrogenetically similar to the ca. 132 Ma False Bay dykes around Cape Town. Therefore, we propose to unify all these coeval and compositionally similar dykes into one large igneous province (LIP) termed the Greater Cederberg-False Bay Large Igneous Province (GCF-LIP).</p>}},
  author       = {{Kingsbury, C. G. and Altermann, W. and Kramers, J. and Ernst, R. E. and Söderlund, U. and Klausen, M. B.}},
  issn         = {{1012-0750}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{471--484}},
  publisher    = {{Geological Society of South Africa}},
  series       = {{South African Journal of Geology}},
  title        = {{The Greater Cederberg−False Bay Large Igneous Province in South Africa : A southern node of widespread magmatism associated with South Atlantic rifting}},
  url          = {{http://dx.doi.org/10.25131/sajg.126.0023}},
  doi          = {{10.25131/sajg.126.0023}},
  volume       = {{126}},
  year         = {{2023}},
}