Azougui Fm

The Azougui Fm consists of interbedded mudstone, siltstone, sandstone, and dolostone. It is generalized as "carbonate" in the regional stratigraphic diagram of Martin-Monge et al. (2016). The Azougui Fm is dominated by massive, fissile, purple-red mudstone with green reduction spots and bands, and thin lenticular beds of medium-grained sandstone. Thin siltstone interbeds are commonly greenish-gray and micaceous. Sandy dolostone beds are up to 0.5 m thick, buff-colored on weathered surfaces and planar-bedded or cross-laminated with halite pseudomorphs and desiccation cracks. Dolostones are pinkish-gray, massive or stromatolitic, and contain chert nodules and desiccation cracks. The top of the Azougui Formation is locally characterized by a green mudstone with very thin ironstone beds. Barite is present in the formation as mm-sized inclusions or broadly strata-bound veins (Pitfield et al., 2004). Minor occurrences of copper and rarely zinc at Tinzac (Mauk, 2015) have been found in dolostone, dolomitic sandstone, and intraformational conglomerate beds of the Azougui Formation (Pitfield et al., 2004; Gunn et al., 2004). At Taradent, sediment-hosted copper mineralization occurs at three stratigraphic levels within the Azougui Formation. The lowest mineralized horizon contains traces of malachite, chalcopyrite, chalcocite and covellite sporadically distributed along several hundred meters of strike length and is associated with barite veins and stockworks in an interbedded calcareous sandstone or breccia (Taylor and Giles, 2013).

See Hohd Super Gr entry for discussion of age assignments to Neoproterozoic units. The legend to the USGS regional map (Bradley et al., 2015) indicates that the onset of the lowest units begins shortly after 1600 Ma. Temporarily, the onset is arbitrarily set here as 1500 Ma (mid-Calymmian); with its lower Char Gr plus Foum Chor Fm (and regional equivalents) arbitrarily placed as upper Calymmian through lower Ectasian (1500 to 1300 Ma), then the major regional "D2" regional unconformity. Formations within the Char Gr are scaled following their relative proportions in the stratigraphic figure from Martin-Monge et al. (2016)

Azougui Fm marks the continued evolution of the depositional environment from a continental to a shallow marine, probably evaporative setting. The purple-red mudstones are interpreted as low-energy deposits seaward of a tidal flat environment. The dolomitic sandstones and sandy dolostones indicate an intertidal environment that underwent low-energy tidal currents, saline waters, and periodic subaerial exposure as indicated by desiccation cracks and halite pseudomorphs (Pitfield et al., 2004).