1.38 GA U-PB BADDELEYITE AGES FOR DOLERITIC DYKES IN THE ANTI-ATLAS OF MOROCCO

In the Bas-Draa inlier part of Anti-Atlas, which corresponds to the northern edge of West Africa Craton (WAC), the Paleoproterozoic basement is intruded by mafic dykes of various trends, generally thought to be either Pan-African or Eburnean in age. Two doleritic dykes from the Bas-Draa Inlier have been dated using ID-TIMS U-Pb baddeleyite yielding matching emplacement ages of 1384±6 Ma (MSWD=1.4) and 1380±9 Ma (MSWD=0.84). With their NE and NNW trends these dykes converge to the north, suggesting a magmatic centre (mantle plume?) along the northern cratonic margin, and possibly linked to breakup or attempted breakup. Identical 1.38 Ga ages are present on other crustal blocks (e.g., Laurentian, Siberian, East European, Congo, Kalahari and other cratons; Ernst et al., 2008 Prec. Res. 160: 159-178) consistent with this 1.38 Ga magmatism marking a major breakup stage of the Nuna supercontinent that also involved the West African Craton. The apparent absence of 1380 Ma flood basalts and sills is consistent with the Mesoproterozoic gap of sedimentation (caused by erosion) recorded in the Anti-Atlas.