Did the Paleoproterozoic Supercontinent Columbia (Nuna) Start Breaking Up Almost Immediately?

The 1750 Ma Magmatic Event of the West African Craton (Anti-Atlas, Morocco)

Authors:

1. Nasrrddine Youbi (a, b)
2. Djiky Kouyaté (a)
3. Ulf Söderlund (c, d)
4. Richard E. Ernst (e, f)
5. Abderrahmane Soulaimani (a)
6. Ahmid Hafid (g)
7. Moha Ikenne (h)
8. Abdelhakim El Bahat (h)
9. Hervé Bertrand (i)
10. Khalid Rkha Chaham (a)
11. Mohamed Ben Abbou (j)
12. Abdelaziz Mortaji (h)
13. Mustapha El Ghorfi (k)
14. Mohamed Zouhair (k)
15. M’hamed El Janati (a)

Affiliations:

a. Department of Geology., Faculty of Sciences-Semlalia, Cadi Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco

b. Centro de Geologia da Universidade de Lisboa (CeGUL), Faculdade de Ciências (FCUL), Departamento de Geologia (GeoFCUL), Campo Grande C6, 1749-016 Lisboa, Portugal

c. Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden

d. The Swedish Museum of Natural History, SE-114 18 Stockholm, Sweden

e. Department of Earth Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Canada K1S 5B6

f. Ernst Geosciences, 43 Margrave Ave Ottawa, Canada K1T 3Y2

g. Department of Geology, Faculty of Sciences & Technics Guéliz, Cadi Ayyad University, P.O. Box 549, Abdelkarim El Khattabi Avenue, Guéliz, Marrakech, Morocco

h. Department of Geology, Faculty of Sciences, Ibnou Zohr University, P.O. Box 28/S, Agadir, Morocco

i. Laboratoire de Géologie de Lyon, UMR CNRS 5276, ENS de Lyon et Université Lyon1, 46, Allée d’Italie, 69364 Lyon, France

j. Department of Geology., Faculty of Sciences Dhar Al Mahraz, Sidi Mohammed Ben Abdellah University, Fès, Morocco

k. Managem-ONA Group, Twin Center, Tour A, Angle Bd Zerktouni & Massira Khadra, Casablanca, Morocco

Abstract:

The Precambrian inliers of the Anti Atlas belt located at the southern part of Morocco contain numerous mafic dyke and sill swarms thought to represent the erosional remnants of Proterozoic Large Igneous Provinces (LIPs). As part of a continuing research campaign to date and characterize these LIPs, four dykes have been dated by the U-Pb TIMS (Thermal Ionization Mass Spectrometry) method on baddeleyite and zircon: ca. 1758 Ma in the Tagragra of Akka inlier, 1741 ± 10 Ma in the Tafeltast-Kerdous inlier 1746.8 ± 3.7 Ma in the Iguerda-Taïfast and 1734 ± 5 Ma in the Zenaga inlier. The age matches (and chemical features akin to continental flood basalts) confirm a widespread intraplate magmatic event at 1750 Ma, herein termed the Tagragra of Akka LIP, that represents an important new magmatic ‘barcode’ line for the West African Craton (WAC). Contemporaneous 1750 Ma LIP magmatism is reported in other crustal blocks including northwestern Laurentia and Siberia; together with the newly defined Tagragra of Akka event of the Anti Atlas region of the WAC this widespread 1750 Ma magmatism is postulated to collectively constitute a single huge LIP associated with a breakup attempt of Nuna (Columbia) shortly after its final assembly at ca. 1.8 Ga.