Données nouvelles sur le protérozoïque inférieur du domaine nord-armoricain (France): age et signification

1980 ◽  
Vol 17 (4) ◽  
pp. 532-538 ◽  
Author(s):  
Bernard Auvray ◽  
René Charlot ◽  
Philippe Vidal
Keyword(s):  
West African ◽  
The Other ◽  
The West ◽  
West African Craton ◽  
Northern Margin ◽  
The North ◽  
Upper Proterozoic ◽  
Lower Proterozoic ◽  
Proterozoic Basement ◽  
Armorican Massif

Orthogneisses from the Tregor area of the North Armorican Massif have been dated using the U/Pb method on zircons. Ages of between 1.8 and 2.0 Ga have been obtained, thus significantly extending the known size of the Lower Proterozoic basement in this area. It is argued that the presence of such a substantial area of basement is a further argument for an Upper Proterozoic (Brioverian) south-dipping subduction zone which was located to the north of the Armorican Massif. On the other hand, the similarities between the North Armorican block and the northern margin of the West African craton during the Proterozoic are emphasized.

Interprétation géodynamique du domaine pan-africain (Précambrien terminal) de l'Anti-Atlas (Maroc) à partir de données géologiques et géochronologiques

1980 ◽  
Vol 17 (1) ◽  
pp. 142-155 ◽  
Author(s):  
M. Leblanc ◽  
J. R. Lancelot
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
West African ◽  
The Other ◽  
Geochronological Data ◽  
Geodynamic Evolution ◽  
The West ◽  
West African Craton ◽  
Northern Margin ◽  
Pan African

U–Pb and Rb–Sr ages performed in the Anti-Atlas (Morocco), especially in Bou Azzer area, demonstrate a Pan-African orogeny (680–570 Ma), along the northern margin of the West African craton (2000 Ma). Geological and geochronological data allow the reconstitution of a coherent succession of events of Pan-African ages. The geodynamic evolution of this domain comprises a stage of oceanic opening (ophiolites) followed with a stage of closure: obduction of the ophiolites on the craton, then subduction under an active continental margin. This segment of the Pan-African belt can be correlated with the other parts of the belt, located on the eastern margin of the West African craton.

Évolution paléogéographique de la marge nord-ouest de l'Afrique du Cambrien à la fin du Carbonifère (du Maroc au Libéria)

1991 ◽  
Vol 28 (7) ◽  
pp. 1121-1130 ◽  
Author(s):  
Michel Villeneuve ◽  
Jean-Jacques Cornée
Keyword(s):  
West African ◽  
The West ◽  
Lower Paleozoic ◽  
West African Craton ◽  
Middle Cambrian ◽  
Early Devonian ◽  
Middle Ordovician ◽  
The North ◽  
Marine Platform ◽  
General Regression

Paleogeographic reconstructions of Paleozoic time are presented for the northwest margin of the West-African Craton. An extensional regime and a marine transgression were dominant during the Early Cambrian. During the Middle Cambrian, the Rokélides orogen was responsible for the sea regression to the south, while the proto-Atlantic opening was active to the north of the Reguibat shield. A large stable marine platform was present during Early and Middle Ordovician. A general regression and the formation of the West-African Inlandsis took place during the Late Ordovician. During Silurian time, this sea transgressed over most of the African platform. Incipient Hercynian deformations during the Early Devonian produced horsts and grabens in Morocco. At the end of the Devonian and the beginning of the Carboniferous, the sea was restricted to isolated basins and tectonic trenches. Collision between West Africa and North America during the Late Carboniferous transformed the Lower Paleozoic margin into an Hercynian orogenic belt, whose structure is controlled by the presence of crustal blocks, generated as early as the Cambrian, and probably reflecting, in turn, older Panafrican zones of weakness. [Translated by the Journal]

scholarly journals Early Neoproterozoic oxygenation dynamics along the northern margin of the West African Craton, Anti-Atlas Mountains, Morocco

2021 ◽  
pp. 120404
Author(s):  
Ernest Chi Fru ◽  
Olabode Bankole ◽  
Ibtissam Chraiki ◽  
Nassrddine Youbi ◽  
Marc-Alban Millet ◽  
...  
Keyword(s):  
West African ◽  
The West ◽  
West African Craton ◽  
Northern Margin ◽  
Atlas Mountains ◽  
Early Neoproterozoic

Cover gneisses of the Monashee Terrane: a record of synsedimentary rifting in the North American Cordillera

1990 ◽  
Vol 27 (5) ◽  
pp. 712-726 ◽  
Author(s):  
Robert J. Scammell ◽  
Richard L. Brown
Keyword(s):  
North American ◽  
Alkaline Magmatism ◽  
Pyroclastic Deposits ◽  
North American Cordillera ◽  
Metasedimentary Rocks ◽  
The North ◽  
Upper Proterozoic ◽  
Lower Proterozoic ◽  
Proterozoic Basement ◽  
Siliciclastic Sediments

The Monashee Terrane of southeastern British Columbia is composed of Lower Proterozoic basement gneisses unconformably overlain by cover gneisses. The latter constitute a thick (> 2000 m) and laterally extensive (> 150 km) upper-amphibolite-grade succession of metasedimentary rocks, locally intercalated with minor intrusive and extrusive units. This succession is interpreted as reflecting initial broad, amagmatic subsidence and sedimentation on a cratonic platform (basement gneisses), most likely of North American affinity. Throughout most of the terrane, syndepositional magmatism is first marked by a laterally extensive (> 100 km) stratiform pyroclastic carbonatite, which is part of intermittent (long-lived?) alkaline magmatism. One alkaline body was intruded at ca. 740 ± 36 Ma (U–Pb zircon), suggesting that it may be part of initial Windermere rifting. Post-pyroclastic-carbonatite syndepositional extensional tectonism is further evidenced at the north end of the terrane by interlayered mature and immature siliciclastic sediments, with rapid facies changes, intercalated with ultramafic and mafic sills and flows, plus minor felsic pyroclastic deposits. All of these later deposits lie above stratigraphy correlated with strata hosting a stratiform Pb–Zn deposit with an Early Cambrian galena Pb-isotope age and, therefore, may be correlative with a rift–drift transition recorded in Hamill Group strata to the east. Rift tectonism recorded in cover gneisses may reflect one or more documented rift and rift–drift events recorded in Upper Proterozoic to Lower Cambrian strata of the western North American continental terrace prism.

scholarly journals The Late Neoproterozoïc Continental Tholeiitic Basalts of the Toubkal Inlier (Western High-Atlas, Morocco): A Post-Pan-African Rifting Witness in the Northern Margin of the West African Craton

2016 ◽  
Vol 06 (08) ◽  
pp. 509-516 ◽  
Author(s):  
Ghalem Zahour ◽  
Hassan El Hadi ◽  
Abdelfatah Tahiri ◽  
Youssef Zerhouni ◽  
Saida Alikouss ◽  
...  
Keyword(s):  
West African ◽  
The West ◽  
West African Craton ◽  
High Atlas ◽  
Northern Margin ◽  
Pan African

Detrital pyrope garnets from the El Kseibat area, Algeria: A glimpse into the lithospheric mantle beneath the north-eastern edge of the West African Craton

2012 ◽  
Vol 63 ◽  
pp. 1-11 ◽  
Author(s):  
Mohammed Kahoui ◽  
Felix V. Kaminsky ◽  
William L. Griffin ◽  
Elena Belousova ◽  
Yamina Mahdjoub ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
West African ◽  
The West ◽  
West African Craton ◽  
The North ◽  
North Eastern ◽  
Eastern Edge
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