The Aganane Formation represents a photozoan-dominated large carbonate platform, formed in a warm, semi-arid to arid climate, were clear, nutrient-poor waters, while ooids, evaporites and calcretes indicate high evaporation and limited freshwater input, and diagenetic features even reflect major events such as
Hurricanes. The formation displays marked west–east variations: red marly brackish deposits grade into evaporitic lagoonal, then into marly–dolomitic and marly–calcareous lagoonal–marine facies. The surrounding low-lying
hinterland experienced little runoff and was primarily eroded by wind. North of the
Demnate fault, a broad subsiding
tidal flat developed, where carbonate deposits with gypsum relics and
stromatolitic laminites formed, interspersed with desiccation cracks and gypsum precipitated in
sebkhas. Along this fault, massive
lignite layers appear, probably derived from degraded forests to the south, as indicated by root traces in basal sandstones near
Aït Tioutline. Herbivorous and carnivorous dinosaurs also inhabited these coastal marshlands. Marginal intertidal zones experienced hypersaline conditions, while central and southern areas maintained near-normal marine salinity during transgressions. The "Assemsouk Structure", a massive bivalve reef (125 m high, 1.25 km long), preserves growth stages with corals and
stromatolites, later faulted into a narrow turbiditic trough and buried by marine marls. The depositional environments span from supratidal flats to subtidal zones, with regressive phases marked by
barrier islands, followed by anoxic lagoonal shales with coal seams and plant fragments.
Depositional settings dinosaur, at the top of an emersive "shallowing upward" carbonate cycleThe Aganane Formation records a spectrum of shallow marine to coastal depositional environments during the Pliensbachian. The lower and middle parts are dominated by light gray, dolomitic limestones with rhythmic layering, representing tidal-flat–like coastal zones periodically inundated by seawater. Localities such as Ait Athmane and Tizi n'Terghist preserve rhizoliths,
tree trunks, red clay paleosols, and
pisoids, indicative of
pedogenic or freshwater conditions with episodic exposure. Other sites show biodetritic limestones with emersion features, including dolomitization, mud cracks, plant remains, and dinosaur footprints. Red and white marls, thin dolomite layers, and evaporites suggest alternating exposure and flooding, reminiscent of modern sabkha environments, with tropical conditions comparable to the
Andros Island model in the
Bahamas. Gray, organic-rich sediments indicate low-oxygen, calm-water deposition, with subtidal oncolitic lime wackestones reflecting occasional higher-energy mixing. In wave-exposed zones, sediments coarsen and reef-related bioclastic limestones appear, with
coral colonies and
sea urchins forming patch reefs. These reefs protected inner lagoons, allowing finer sediments to accumulate behind them. Frequent
episodic storms caused repeated reworking and lateral displacement of facies, generating asymmetric cycles 2-4 meters thick in shallow lagoon bottoms and behind offshore bars or reef belts. == Paleogeography ==