Facies and sequence stratigraphy of an estuarine incised-valley fill: Lower Aptian Bouzergoun Formation, Agadir Basin, Morocco

Lower Aptian strata exposed in the Agadir Basin of the Western High Atlas r epresent the fill of a fluvial valley incised during the Early Aptian (Bedo ulian) sea-level fall. The valley fill comprises a diverse assemblage of li thofacies that can be grouped into lowstand, transgressive, and highstand s ystems tracts. Fluvial conglomerates and pebbly sandstones, referred to the lowstand systems tract, incised into the underlying Late Barremian margina l-marine deposits to form a basal sequence boundary. As sea level began to rise, fluvial deposits were reworked into alternating couplers of moderatel y bioturbated sandstones and mudstones that display tidally-influenced, inc lined, heterolithic strata. The transgressive systems tract comprises the b ulk of the estuarine fill and consists of a seaward and landward thinning w edge of tidally-influenced fluvial, tidal flat, estuarine point-bar and bay -fill deposits. Highstand infilling of the valley was characterised by estu arine mouth bars and shoal progradation. (C) 2001 Academic Press.