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Birimian crustal growth in the West African Craton : U-Pb, O and Lu-Hf isotope constraints from detrital zircon in major rivers

Petersson, Andreas LU ; Scherstén, Anders LU ; Kristinsdóttir, Bara; Kemp, Anthony and Whitehouse, Martin (2018) In Chemical Geology 479. p.259-271
Abstract

Combined U-Pb, O and Lu-Hf isotope analyses of detrital zircon grains from five major rivers in Ghana are used to investigate the growth and evolution of the Birimian terrane of the West African Craton. The majority of the analysed zircon yields supra-chondritic εHf values, suggesting derivation from primarily juvenile host magmas. Zircon grains from the Birim River in southwestern Ghana deviate from the generally juvenile trend, where the sub-chondritic εHf but mantle-like δ18O of the 2.15 Ga population suggest reworking of ancient, but unweathered, meta-igneous crust. Hf-O isotope data from detrital zircons of the remaining rivers are consistent with sequential crust generation between ca. 2.2 and 2.1... (More)

Combined U-Pb, O and Lu-Hf isotope analyses of detrital zircon grains from five major rivers in Ghana are used to investigate the growth and evolution of the Birimian terrane of the West African Craton. The majority of the analysed zircon yields supra-chondritic εHf values, suggesting derivation from primarily juvenile host magmas. Zircon grains from the Birim River in southwestern Ghana deviate from the generally juvenile trend, where the sub-chondritic εHf but mantle-like δ18O of the 2.15 Ga population suggest reworking of ancient, but unweathered, meta-igneous crust. Hf-O isotope data from detrital zircons of the remaining rivers are consistent with sequential crust generation between ca. 2.2 and 2.1 Ga. Oxygen isotope data suggest that the contribution from Archaean sedimentary material to felsic magmas was below 30%, and in most cases below 10%. Zircon with strongly positive εHf values and elevated δ18O indicate rapid reworking of juvenile crust within southern Ghana. An increase towards heavier oxygen isotope signatures over time suggests a maturing arc system with rapid recycling of juvenile supracrustal material during the evolution of the Birimian terrane.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Baoulé Mossi, Detrital zircon, Lu-Hf, Oxygen, U-Pb, West African Craton
in
Chemical Geology
volume
479
pages
259 - 271
publisher
Elsevier
external identifiers
  • scopus:85040998363
ISSN
0009-2541
DOI
10.1016/j.chemgeo.2018.01.021
language
English
LU publication?
yes
id
797a2b9f-2124-4ff7-92bf-49e167f2451f
date added to LUP
2018-02-06 10:33:46
date last changed
2018-05-29 10:03:25
@article{797a2b9f-2124-4ff7-92bf-49e167f2451f,
  abstract     = {<p>Combined U-Pb, O and Lu-Hf isotope analyses of detrital zircon grains from five major rivers in Ghana are used to investigate the growth and evolution of the Birimian terrane of the West African Craton. The majority of the analysed zircon yields supra-chondritic ε<sub>Hf</sub> values, suggesting derivation from primarily juvenile host magmas. Zircon grains from the Birim River in southwestern Ghana deviate from the generally juvenile trend, where the sub-chondritic ε<sub>Hf</sub> but mantle-like δ<sup>18</sup>O of the 2.15 Ga population suggest reworking of ancient, but unweathered, meta-igneous crust. Hf-O isotope data from detrital zircons of the remaining rivers are consistent with sequential crust generation between ca. 2.2 and 2.1 Ga. Oxygen isotope data suggest that the contribution from Archaean sedimentary material to felsic magmas was below 30%, and in most cases below 10%. Zircon with strongly positive ε<sub>Hf</sub> values and elevated δ<sup>18</sup>O indicate rapid reworking of juvenile crust within southern Ghana. An increase towards heavier oxygen isotope signatures over time suggests a maturing arc system with rapid recycling of juvenile supracrustal material during the evolution of the Birimian terrane.</p>},
  author       = {Petersson, Andreas and Scherstén, Anders and Kristinsdóttir, Bara and Kemp, Anthony and Whitehouse, Martin},
  issn         = {0009-2541},
  keyword      = {Baoulé Mossi,Detrital zircon,Lu-Hf,Oxygen,U-Pb,West African Craton},
  language     = {eng},
  pages        = {259--271},
  publisher    = {Elsevier},
  series       = {Chemical Geology},
  title        = {Birimian crustal growth in the West African Craton : U-Pb, O and Lu-Hf isotope constraints from detrital zircon in major rivers},
  url          = {http://dx.doi.org/10.1016/j.chemgeo.2018.01.021},
  volume       = {479},
  year         = {2018},
}