The Carboniferous volcano-sedimentary depocentre of Tazekka Massif (Middle-Atlas, Morocco): new observations and geodynamic implications

Abstract

The integrated analysis of thrust structures and facies allows us to interpret the Carboniferous volcano-sedimentary complex of Tazekka massif as a compressive sub-basin controlled mainly by the Hajra Sbaa–Merja Caï’d northwest-verging thrust-propagation fold. The tectono-sedimentary sequence (conglomerates, greywacke and shale) is associated with an extrusive magmatism comprising basalts, andesites and rhyolites, under effusive and volcanoclastic facies (or rhyolites with exotic blocks), of orogenic calk-alkaline nature, which is consistent with a context of continental subduction. These results, and the comparison of regional contraction ages in the Moroccan Meseta, integrate the Carboniferous volcano-sedimentary depocentre of Tazekka massif in the wedgetop depozone of a foreland basin system generated by two north-west thrusted piggy-back sequences (aged from Fameno-Tournaisian to upper Visean-lower Westphalian) from the eastern Meseta to the western Meseta of Morocco.