Enigmatic 1146 ± 4 Ma old granite in the southeastern rim of the West African craton, now part of the Dahomeyan orogenic belt in Ghana
(2020) In Journal of African Earth Sciences 167.- Abstract
A unique exposure of a strongly deformed late Mesoproterozoic augen-granite (U–Pb zircon age 1146 ± 4 Ma) was detected within rocks on the eastern rim of the West African Craton. These rocks, together with their sedimentary cover, were reworked during the Neoproterozoic Pan-African Dahomeyan orogeny, and are now incorporated in the Dahomeyan orogenic belt of southeast Ghana. To the authors’ knowledge no similar ages have been reported from elsewhere in the West African Craton or in the Pan-African orogenic belts farther north or their continuation in northeastern Brazil. Most other granitoid rocks in the Dahomeyan belt are of Palaeoproterozoic age. Two of them were dated for this study and yielded Concordia ages of 2067 ± 15 Ma and 2119... (More)
A unique exposure of a strongly deformed late Mesoproterozoic augen-granite (U–Pb zircon age 1146 ± 4 Ma) was detected within rocks on the eastern rim of the West African Craton. These rocks, together with their sedimentary cover, were reworked during the Neoproterozoic Pan-African Dahomeyan orogeny, and are now incorporated in the Dahomeyan orogenic belt of southeast Ghana. To the authors’ knowledge no similar ages have been reported from elsewhere in the West African Craton or in the Pan-African orogenic belts farther north or their continuation in northeastern Brazil. Most other granitoid rocks in the Dahomeyan belt are of Palaeoproterozoic age. Two of them were dated for this study and yielded Concordia ages of 2067 ± 15 Ma and 2119 ± 13 Ma. Lower intercepts around 600 Ma in Wetherill discordia diagrams demonstrate disturbance of the U–Pb systems during the Pan-African orogenic cycle. Chemical data indicate that the Palaeoproterozoic granitoid rocks are arc-type granites (sensu lato), while the Mesoproterozoic augen-granite has the chemical composition of an alkaline within-plate granite. Chemical, whole rock Sm–Nd and zircon Lu–Hf data suggest that the magma that yielded the augen-granite was formed by melting within a mafic Palaeoproterozoic source at moderate crustal depth. The occurrence of a Mesoproterozoic granite in the (now) eastern margin of the West African Craton is evidence of a previously unknown igneous event within this terrain.
(Less)
- author
- Kalsbeek, Feiko ; Frei, Dirk ; Schersten, Anders LU ; Frei, Robert ; Gerdes, Axel and Kalvig, Per
- organization
- publishing date
- 2020
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Dahomeyan orogenic belt of Ghana, Late mesoproterozoic granite, U–Pb zircon dating, West African Craton, Whole rock Sm–Nd, Zircon Lu–Hf
- in
- Journal of African Earth Sciences
- volume
- 167
- article number
- 103814
- publisher
- Elsevier
- external identifiers
-
- scopus:85083374683
- ISSN
- 1464-343X
- DOI
- 10.1016/j.jafrearsci.2020.103814
- language
- English
- LU publication?
- yes
- id
- 25785317-2430-464a-a3cc-3be430d112b6
- date added to LUP
- 2020-04-28 10:48:33
- date last changed
- 2022-04-18 21:56:19
@article{25785317-2430-464a-a3cc-3be430d112b6,
abstract = {{<p>A unique exposure of a strongly deformed late Mesoproterozoic augen-granite (U–Pb zircon age 1146 ± 4 Ma) was detected within rocks on the eastern rim of the West African Craton. These rocks, together with their sedimentary cover, were reworked during the Neoproterozoic Pan-African Dahomeyan orogeny, and are now incorporated in the Dahomeyan orogenic belt of southeast Ghana. To the authors’ knowledge no similar ages have been reported from elsewhere in the West African Craton or in the Pan-African orogenic belts farther north or their continuation in northeastern Brazil. Most other granitoid rocks in the Dahomeyan belt are of Palaeoproterozoic age. Two of them were dated for this study and yielded Concordia ages of 2067 ± 15 Ma and 2119 ± 13 Ma. Lower intercepts around 600 Ma in Wetherill discordia diagrams demonstrate disturbance of the U–Pb systems during the Pan-African orogenic cycle. Chemical data indicate that the Palaeoproterozoic granitoid rocks are arc-type granites (sensu lato), while the Mesoproterozoic augen-granite has the chemical composition of an alkaline within-plate granite. Chemical, whole rock Sm–Nd and zircon Lu–Hf data suggest that the magma that yielded the augen-granite was formed by melting within a mafic Palaeoproterozoic source at moderate crustal depth. The occurrence of a Mesoproterozoic granite in the (now) eastern margin of the West African Craton is evidence of a previously unknown igneous event within this terrain.</p>}},
author = {{Kalsbeek, Feiko and Frei, Dirk and Schersten, Anders and Frei, Robert and Gerdes, Axel and Kalvig, Per}},
issn = {{1464-343X}},
keywords = {{Dahomeyan orogenic belt of Ghana; Late mesoproterozoic granite; U–Pb zircon dating; West African Craton; Whole rock Sm–Nd; Zircon Lu–Hf}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Journal of African Earth Sciences}},
title = {{Enigmatic 1146 ± 4 Ma old granite in the southeastern rim of the West African craton, now part of the Dahomeyan orogenic belt in Ghana}},
url = {{http://dx.doi.org/10.1016/j.jafrearsci.2020.103814}},
doi = {{10.1016/j.jafrearsci.2020.103814}},
volume = {{167}},
year = {{2020}},
}