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

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-Tanst 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 tarcode' 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 Nuns (Columbia) shortly after its final assembly at ca. 1.8 Ga. (C) 2013 Elsevier B.V. All rights reserved.