New Petro-Geochemical Data on Carboniferous Mafic Rocks in the Achemmach Area (NW, Fourhal Basin-Moroccan Central Massif)

The Achemmach region is located 40 km to the SW from Meknes city and 6 NE frm Hammam mine. It part of Paleozoic massif Central Morocco. studied area formed by two rock-types: (i) a meta-sedimentary sequence composed Middle Visean limestone shale-sandstone withflyschoid Upper Visean-Namurian age, (ii) magmatic rock series represented volcanic rocks (pillow-lavas), hypovolcanic (dolerites) olivine-bearing gabbros.Based on emplacement model, structural framework, relative chronology petrogeochemistry rocks, for first time in this we distinguish: dm m-sized greenish pillow-lavas, with sharp borders radius fractures underlined fine pelitic sedimentary intercalations, indicating recurrent activity short episodes. Plagioclases pyroxenes (augite) microlites, more rarely phenocrystals, are recognizable glassy matrix devoid olivine. Deformed, metamorphosed altered dolerites dikes intrude formations. They have an overall NE-SW direction NW dip. sericitized plagioclases, associated partially totally amphibolitized pyroxenes, tourmaline differentdegrees chlorite substitution, rutile opaque minerals, microliticmesostasis (iii) gabbros, outcropping variable dimensions (a few meters 20 m). gabbros granular texture mainly made olivine, titanite, rutile, apatite minerals. All igneous minerals undergone different degrees replacement secondary minerals; plagioclases albitized, epidotized olivine serpentinized chloritized. Thepetro-geochemical study these bodies demonstrates that pillow-lavas basalts alkaline affinity, while thought transitional affinity (alkaline-tholeiitic). Therefore, formations would been set up anorogenic intra-continental geodynamic context, corresponding basin magmatism little evolved opening.