Evidence of a Paleoproterozoic basement in the Moroccan Variscan Belt (Rehamna Massif, Western Meseta)

摘要

For the first time, an Eburnian magmatic event has been identified in the Rehamna Massif (Moroccan Variscan Belt, Western Meseta) located north of the South Meseta fault. The best estimate of the crystallization age of rhyolitic porphyry is given by a weighted mean Pb-207/Pb-206 age of 2050.6 +/- 3 Ma (Rhyacian-Orosirian). The new U-Pb age obtained for rhyolitic porphyry from the Rehamna Massif is of great relevance for improving geological knowledge about the boundaries of the WAC because: (i) it overlaps the older Eburnian magmatic event described in the Anti-Atlas belt and the Icartian magmatic event of the European Variscan Be (ii) this suggests that exists Paleoproterozoic basement in the Western Meseta, a hundred kilometers further to the north of the South Meseta fault, as old continental crust slivers preserved in the Cadomian and Variscan belts; and (iii) this means that the Cambrian transgression in the Western Meseta probably took place based on a more complex structural architecture affecting the Precambrian basement composed not only of Ediacaran rocks, as has been suggested in the literature, but also with Paleoproterozoic rocks (ca. 2.05 Ga) as discovered in this study. (C) 2015 Elsevier B.V. All rights reserved.