Revised stratigraphic framework for the lower Anti-Atlas supergroup based on U–Pb geochronology of magmatic and detrital zircons (Zenaga and Bou Azzer-El Graara inliers, Anti-Atlas Belt, Morocco)
U–Pb geochronology of magmatic and detrital zircons (Zenaga and Bou Azzer-El Graara inliers, Anti-Atlas Belt, Morocco) and a reassessment of the published constraints suggest a revised stratigraphic framework for the lower Anti-Atlas Supergroup. Five major unconformity-bounded lithostratigraphic packages are here distinguished: the two lower units of Paleoproterozoic age are named the Tasserda-Taghatine Group (2030–1706 Ma) and the Oumoula (Mimount) Formation (ca. 1745–1650 Ma); the third unit of Paleoproterozoic to Neoproterozoic age (ca. 1650 to >883 Ma) is the Tizi n'Taghatine Group; the fourth and fifth units of Neoproterozoic age are the ca. 883 Ma Tachdamt and the ca. 700 Ma Bleida formations. Implications of this revised stratigraphic framework include: 1) the Tasserda-Taghatine Group might be linked to the post-orogenic collapse after the Eburnean Orogeny; 2) the Tizi n'Taghatine Group might be ca. 1.1 Ga in age based on proposed correlation with the Taoudeni Basin succession in Mauritania; 3) the Bleida Formation likely reflects deposition in the foreland basin at the early stage of the Pan-African Orogeny; 4) the Oumoula (Mimount) Formation, Tizi n'Taghatine Group, and Tachdamt Formation potentially record extensional events within the Nuna/Columbia and Rodinia supercontinents; 5) the provenance of the lower Anti-Atlas Supergroup (based on our new detrital zircon dating) is mainly from the West African craton along with possible contributions from other cratons such as Amazonia and the Sahara Metacraton; 6) the flood basalt sequence of the Tachdamt Formation likely belongs to the ca. 885-883 Ma intraplate Iguerda-Taïfast Large Igneous Province (LIP) event defined by previously dated dykes in the Iguerda and Taïfast inliers; and 7) the 1650 Ma Zenaga LIP can be potentially linked with LIP magmatism in Baltica and Laurentia.
|Keywords||Anti-Atlas Belt, Lower Anti-Atlas supergroup, Morocco, Proterozoic, U–Pb geochronology|
|Journal||Journal of African Earth Sciences|
Ait Lahna, A. (Abdelhak), Youbi, N. (Nasrrddine), Tassinari, C.C.G. (Colombo Celso Gaeta), Basei, M.A.S. (Miguel Angelo Stipp), Ernst, R.E, Chaib, L. (Latifa), … Bekker, A. (Andrey). (2020). Revised stratigraphic framework for the lower Anti-Atlas supergroup based on U–Pb geochronology of magmatic and detrital zircons (Zenaga and Bou Azzer-El Graara inliers, Anti-Atlas Belt, Morocco). Journal of African Earth Sciences, 171. doi:10.1016/j.jafrearsci.2020.103946