Petrogenesis of the late Ediacaran A-type granites of the western part of the Moroccan Anti-Atlas belt: Insights from U-Pb dating, geochemistry and Sr-Nd isotopes of the Sidi El Houssein, Tafraout and Taourgha intrusions

The U-Pb zircon age carried out on three distinct late Ediacaran granites through the Anti-Atlas yielded 207Pb/235U ages of 584 +/- 2.29/579 +/- 3.83 Ma for Sidi El Houssein granite (Zenaga Inlier), 581 +/- 2.05 Ma for Tafraout granites (Kerdous inlier) and 580 +/- 3.02 Ma for the Taourgha intrusion (Bas-Draa inlier). These pink granites display high SiO2 contents that range from 69.19 to 77.3 wt %. They are mainly peraluminous to weak metaluminous and subalkaline and ferron granites with LILE (Rb, K, Th) and HFSE (Ta, Zr, Hf) enrichment, with depletions in Ba, Nb, Sr, and Ti. These rocks have relatively high zircon saturation temperatures (700-900 degrees C), high Zr + Nb + Ce + Y contents >350 ppm), and 10,000 x Ga/Al ratios> 2.6 that are typical of A-type granites. Isotopic compositions show that the granitoids have variable (87Sr/86Sr)i ratios (0.67-0.73), epsilon Nd(t) values (-2.9 to-7.63) and TDM model ages of 1.49-2.53 Ga Suggesting that they were derived from the partial melting of the continental crust with a moderate contribution of the mantle. The late Neoproterozoic granitoids of the Anti -Atlas belt were probably generated during a transtensional regime due to an asthenosphere upwelling that followed the lithospheric delamination related to the collapse of the Panafrican belts.