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Zircon U-Pb-Hf evidence for subduction related crustal growth and reworking of Archaean crust within the Palaeoproterozoic Birimian terrane, West African Craton, SE Ghana

Petersson, Andreas LU ; Scherstén, Anders LU ; Kemp, Anthony; Bara, Kristinsdòttir; Per, Kalvig and Solomon, Anum (2016) In Precambrian Research 275. p.286-309
Abstract
Zircon Lu-Hf isotopic data from granites of southern and northwestern Ghana have been used to investigate the contribution of reworked Archaean bedrock to the Birimian crust of Ghana, West African Craton. Zircon from seven localities in southern Ghana and one locality in western Ghana were analysed. Combined U-Pb and Lu-Hf isotope data suggest juvenile crustal addition between 2.3–2.1 Ga, with a short period of reworking of Archaean crust. Until now, evidence for reworking of Archaean basement during Birimian magmatism in Ghana has hinged on whole-rock Nd model-ages of the Winneba pluton, and sparse inherited zircon grains from mainly northwestern Ghana. Our data suggest that reworking of Archaean crust is greater than previously inferred,... (More)
Zircon Lu-Hf isotopic data from granites of southern and northwestern Ghana have been used to investigate the contribution of reworked Archaean bedrock to the Birimian crust of Ghana, West African Craton. Zircon from seven localities in southern Ghana and one locality in western Ghana were analysed. Combined U-Pb and Lu-Hf isotope data suggest juvenile crustal addition between 2.3–2.1 Ga, with a short period of reworking of Archaean crust. Until now, evidence for reworking of Archaean basement during Birimian magmatism in Ghana has hinged on whole-rock Nd model-ages of the Winneba pluton, and sparse inherited zircon grains from mainly northwestern Ghana. Our data suggest that reworking of Archaean crust is greater than previously inferred, but was limited to between ∼2.14–2.13 Ga. This period of reworking of older crustal components was preceded and succeeded by juvenile crustal addition.



Coupled isotopic data suggest an eastward, mainly retreating arc system with a shorter pulse of accretion between ∼2.18–2.13 Ga and a rapid return to slab retreat during the growth of the Birimian terrane. The accretionary phase initiated melting of sub-continental lithospheric mantle and the overlying Archaean crust, generating magma with sub-chondritic Hf signatures. Subsequent slab retreat led to trench-ward movement of the magmatic activity and the mixture of juvenile and Archaean crust was replaced by uncontaminated juvenile magma. The 2.23 Ga age of the West Accra granodiorite (PK105) demonstrates the emplacement of felsic rocks during the Eoeburnean and pre-dates the suggested plume related rocks, contradicting suggested plume initiated subduction. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Birimian, Crustal growth, Eburnean orogeny, Zircon, Lu-Hf, U-Pb
in
Precambrian Research
volume
275
pages
286 - 309
publisher
Elsevier
external identifiers
  • scopus:84956616813
  • wos:000371841600019
ISSN
0301-9268
DOI
10.1016/j.precamres.2016.01.006
language
English
LU publication?
yes
id
4414fab6-5df6-4013-bd55-0d7ae78c9004 (old id 8566790)
date added to LUP
2016-01-25 13:52:51
date last changed
2017-08-20 03:20:22
@article{4414fab6-5df6-4013-bd55-0d7ae78c9004,
  abstract     = {Zircon Lu-Hf isotopic data from granites of southern and northwestern Ghana have been used to investigate the contribution of reworked Archaean bedrock to the Birimian crust of Ghana, West African Craton. Zircon from seven localities in southern Ghana and one locality in western Ghana were analysed. Combined U-Pb and Lu-Hf isotope data suggest juvenile crustal addition between 2.3–2.1 Ga, with a short period of reworking of Archaean crust. Until now, evidence for reworking of Archaean basement during Birimian magmatism in Ghana has hinged on whole-rock Nd model-ages of the Winneba pluton, and sparse inherited zircon grains from mainly northwestern Ghana. Our data suggest that reworking of Archaean crust is greater than previously inferred, but was limited to between ∼2.14–2.13 Ga. This period of reworking of older crustal components was preceded and succeeded by juvenile crustal addition.<br/><br>
<br/><br>
Coupled isotopic data suggest an eastward, mainly retreating arc system with a shorter pulse of accretion between ∼2.18–2.13 Ga and a rapid return to slab retreat during the growth of the Birimian terrane. The accretionary phase initiated melting of sub-continental lithospheric mantle and the overlying Archaean crust, generating magma with sub-chondritic Hf signatures. Subsequent slab retreat led to trench-ward movement of the magmatic activity and the mixture of juvenile and Archaean crust was replaced by uncontaminated juvenile magma. The 2.23 Ga age of the West Accra granodiorite (PK105) demonstrates the emplacement of felsic rocks during the Eoeburnean and pre-dates the suggested plume related rocks, contradicting suggested plume initiated subduction.},
  author       = {Petersson, Andreas and Scherstén, Anders and Kemp, Anthony and Bara, Kristinsdòttir and Per, Kalvig and Solomon, Anum},
  issn         = {0301-9268},
  keyword      = {Birimian,Crustal growth,Eburnean orogeny,Zircon,Lu-Hf,U-Pb},
  language     = {eng},
  pages        = {286--309},
  publisher    = {Elsevier},
  series       = {Precambrian Research},
  title        = {Zircon U-Pb-Hf evidence for subduction related crustal growth and reworking of Archaean crust within the Palaeoproterozoic Birimian terrane, West African Craton, SE Ghana},
  url          = {http://dx.doi.org/10.1016/j.precamres.2016.01.006},
  volume       = {275},
  year         = {2016},
}