Publication Date:
2021-06-03
Description:
New LA–ICP–MS U–Pb zircon ages from the Nyong Complex of southwestern Cameroon—a part of the West Central African Fold Belt—trace Late Mesoarchean (∼2,850 Ma), Middle Palaeoproterozoic (∼2,080 Ma), and Neoproterozoic (∼605 Ma) events: Two meta‐syenites and the protolith of an amphibolite are Late Mesoarchean; two meta‐granodiorites are Middle Palaeoproterozoic; the amphibolite may have recrystallized in the Middle Palaeoproterozoic; all rocks are overprinted by the Neoproterozoic event. Integration with published data shows that our amphibolite sample has one of the oldest amphibolite‐protolith ages (∼2,810 Ma) reported so far. It shares the Middle Palaeoproterozoic metamorphism/recrystallization with other, previously dated amphibolites. An earlier reported metamorphic zircon age (∼2,090 Ma) from eclogite is somewhat older than the regional Middle Palaeoproterozoic metamorphism/recrystallization ages (∼2,040 Ma) reported from amphibolites. Thus, the eclogite–amphibolite ages may date an exhumation process. A published charnockite age, interpreted as an Early Mesoarchean crystallization age, is older than the Late Mesoarchean meta‐syenite and amphibolite‐protolith dates; its Middle Palaeoproterozoic metamorphism/recrystallization age, however, is identical with the meta‐granodiorites and amphibolites. The Neoproterozoic ages demonstrate the regional overprint of the Nyong Complex during this period. Integration of the Nyong Complex ages with published ones from the entire West Central African Fold Belt, and comparison with those from West Africa and South America, support their common origin from the Palaeoproterozoic collision between the Archean Congo and São Francisco shields.
Description:
(a) South America–Africa fit, showing shields of western Gondwana (modified after Neves et al., 2006). (b) Geological sketch of Cameroon, showing its Archean, Paleo‐, and Neoproterozoic basement and the Cretaceous‐Cenozoic volcano‐sedimentary cover (modified after Castaing et al., 1994; Ngako, Affaton, Nnangue, & Njanko, 2003; Owona, Mvondo Ondoa & Ekodeck, 2013). (c) Geology of the Nyong Complex and related U‐Pb zircon ages. Abbreviations: NEFB – North Equatorial Fold belt, OC – Oubanguide Complex. Published studies: 1 – Toteu et al. (1994), 2 – Lerouge et al. (2006), 3 – Loose & Schenk (2018), 4 – Nkoumbou et al. (2015), and * – present study. (d) Normalized age probability diagrams summarizing the new and published U‐Th‐Pb ages from the West Central African fold belt (including the Nyong Complex), and those from the South American and West African equivalents. Abbreviations: CS – Congo Shield, KS – Kalahari Shield, SFS – São Francisco Shield, TS – Tanzania Shield, WAS – West African Shield.
image
Description:
German Academic Exchange Service
http://dx.doi.org/10.13039/501100001655
Keywords:
551.701
;
556
;
Cameroon
;
LA–ICP–MS U–Pb zircon geochronology
;
Meso‐Neoarchean protoliths
;
Nyong Complex
;
Palaeo‐ and Neoproterozoic reactivations
Type:
article
Permalink
