Seismic architecture, stratigraphy and evolution of a subtropical marine embayment: Maputo Bay, Mozambique

• Describe the seismic stratigraphy of Maputo Bay for the first time
• Relate the stratigraphy to repeating phases of incision, transgression and stillstand
• Compare to other large marine embayments, lagoons and estuaries
• Provide a generic model for large subtropical marine embayments

The seismic stratigraphy, architecture and evolution of a large subtropical embayment, Maputo Bay, Southern Mozambique is described. Nine seismic units are documented; and show repeated phases of incised valley formation and transgressive infilling. Trangressive infilling alternates between the classic wave-dominated transgressive succession of fluvial and central estuarine bay deposits and the filling by intertidal flat and tidal bedforms developed during stages of inlet restriction and shallowing associated with barrier growth at stillstand intervals. Imprinted on the succession are several key facets of subtropical stratigraphy, hurricane-generated erosional surfaces and beachrock horizons. The upper stratigraphy comprises the highstand bayhead delta, a prograding feature constructed by several flood events. In comparison with literature from other similar systems such as lagoons, coastal lakes and estuaries, a generic three stage stratigraphic model of large marine embayments is proposed that includes incision during glaciations; transgressive infilling during deglaciations; and shallowing during the stillstand episodes of the recent deglaciation.