New constraints on the geochronology and Sm-Nd isotopic characteristics of Bas-Draa mafic dykes, Anti-Atlas of Morocco

The Precambrian inliers of the Anti-Atlas belt across the southern part of Morocco contain numerous mafic dyke and sill swarms, which are thought to represent the erosional remnants of Proterozoic Large Igneous Provinces (Lips). As part of an extended research campaign to date and characterize these LIPs, two amphiboles from one dyke within the Bas-Draa inlier (western Anti-Atlas) yielded consistent 40Ar-39Ar ages of 611 Ma +/- 1.3; i.e., evidence of magmatic activity during the Ediacaran (635-542 Ma). Furthermore, Nd isotope ratios and model ages identifies four groups of dykes within the Bas-Draa inlier, all of which were derived from a previously enriched mantle reservoir with very low (143)Nc/Nd-144 ratios (0.51065-0.51170) and corresponding eNd(t) values (-16.44 to 2.45). Such low Nd-ratios arguably reflect either a contribution of crustal components, such as the Paleoproterozoic schisto-granitic basement, or metasomatic modification of the sub-continental lithospheric mantle. (C) 2016 Elsevier Ltd. All rights reserved.