U–Pb baddeleyite and zircon ages of 2040 Ma, 1650 Ma and 885 Ma on dolerites in the West African Craton (Anti-Atlas inliers): Possible links to break-up of Precambrian supercontinents Djiky Kouyaté a, ⁎, Ulf Söderlund b, c , Nasrrddine Youbi a, d, e , Richard Ernst f, g , Ahmid Hafid h , Moha Ikenne i , Abderrahmane Soulaimani a , Hervé Bertrand j , M'hamed El Janati a , Khalid R'kha Chaham a a Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco b Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden c The Swedish Museum of Natural History, SE-114 18 Stockholm, Sweden d National Centre for Scientific and Technical Research, Angle avenues des FAR et Allal El Fassi, Madinat Al Irfane, P.O. Box 8027, Nations Unies, 10102 Rabat, Morocco e Centro de Geologia da Universidade de Lisboa (CeGUL), Portugal f Department of Earth Sciences, Carleton University, Ottawa, Canada K1S 5B6 g Ernst Geosciences, 43 Margrave Ave Ottawa, Canada K1T 3Y2 h Department of Geology, Faculty of Sciences & Technics Guéliz, Cadi Ayyad University, P.O. Box 549, Abdelkarim El Khattabi Avenue, Guéliz, Marrakech, Morocco i Department of Geology, Faculty of Sciences, Ibnou Zohr University, P.O. Box 28/S, Agadir, Morocco j Ecole Normale Supérieure de Lyon et UCBL, Laboratoire des Sciences de la Terre, UMR-CNRS 5570, 46, Allée d'Italie, 69364 Lyon Cedex 07, France abstract article info Article history: Received 14 January 2012 Accepted 23 April 2012 Available online xxxx Keywords: West African Craton Anti-Atlas Dyke swarms U–Pb baddeleyite Geochronology Reconstruction Precambrian inliers of the Anti-Atlas belt in the southern part of Morocco contain numerous dolerite dyke and sill swarms which were previously poorly dated. Four dykes and two sills dated by the U–Pb TIMS method on baddeleyite and zircon provide the first steps toward a magmatic ‘barcode’ for the West African Craton (WAC) and constraints on the timing of breakup of the WAC from Precambrian supercontinents. A 2040±2 Ma (U–Pb zircon) age for a WNW dyke in the Zenaga inlier, matches the published age of a dyke in the Tagragra of Tata inlier, and also those of Eburnean granites observed in several inliers, which are collectively interpreted to rep- resent ca. 2040 Ma bimodal magmatism due to a mantle plume. Based on the presence of matching 2040 Ma ages, the WAC may have been connected to the North Atlantic Craton at the initial stage of fragmentation of a late Archean continent. U–Pb baddeleyite ages of 1656±9 Ma and ca. 1655 Ma from sills in the Zenaga inlier and 1654±16 Ma from a NE-trending dyke in the Agadir Melloul inlier are similar to intraplate magmatic ages in eastern and northern Baltica, and support the SAMBA reconstruction (part of the Nuna supercontinent) of the WAC adjacent to Baltica. Approximate U–Pb ages of 885 Ma for two dykes in the Iguerda-Taïfast and Zenaga in- liers date a NE trending swarm (named herein the Iguerda-Taïfast swarm) which is connected to the initial breakup of the supercontinent Rodinia, and a specific link with the São Francisco/Congo and North China craton is considered. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved. 1. Introduction The West African Craton hosts the remnants of extensive events of tholeiitic/alkaline magmatism represented by mafic sill and dyke swarms in most inliers of the Anti-Atlas chain of southern Morocco. These types of intrusive rocks are potentially important for the re- construction of Precambrian continental blocks into their original relative positions using dyke swarm patterns, radiometric ages and palaeomagnetic signatures (e.g., Bleeker and Ernst, 2006; Buchan et al., 1998; Ernst and Buchan, 1997; Ernst and Bleeker, 2010; Fahrig, 1987; Halls, 1982; Li et al., 2008). On the basis of geochronological data available prior to this study (e.g., Gasquet et al., 2004 and references therein), the Precambrian magmatism in the Anti-Atlas is represented by at least four generations of dykes: (i) tholeiitic dykes of Palaeoproterozoic age such as those in the Tagragra of Tata inlier which have been dated at 2040±6 Ma using the SHRIMP U–Pb method on zircons (Walsh et al., 2002); (ii) microgranite dykes from the Kerdous inlier dated at 1760±3 Ma (Pb–Pb evaporation on zircon, Gasquet et al., 2004), which are carto- graphically and structurally associated with the mafic dykes in this inli- er and in the Tagragra of Akka inlier; (iii) Cryogenian mafic dykes with tholeiitic and alkaline affinities, coeval with the opening of a back-arc oceanic basin in the Central Anti-Atlas (Clauer et al., 1982). A U–Pb zir- con age of 761±2 Ma has been obtained for plagiogranites associated Lithos xxx (2012) xxx–xxx ⁎ Corresponding author at: Laboratory of Geodynamics Magmatic, Georesources and Geohazards (3GEO-LAB), Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco. Tel.: +212 670533753; fax: +212 524 43 74 11. E-mail address: kdjiky@yahoo.fr (D. Kouyaté). LITHOS-02705; No of Pages 14 0024-4937/$ – see front matter. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.lithos.2012.04.028 Contents lists available at SciVerse ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos Please cite this article as: Kouyaté, D., et al., U–Pb baddeleyite and zircon ages of 2040 Ma, 1650 Ma and 885 Ma on dolerites in the West African Craton (Anti-Atlas inliers): Possibl..., Lithos (2012), doi:10.1016/j.lithos.2012.04.028