Contourite on the Limpopo Corridor, Mozambique margin: Long‐term evolution, facies distribution and Plio‐Quaternary processes

Bottom currents are key processes that contribute to the shaping of submarine slopes, with the redistribution of sediments in contourite systems. Despite numerous recent studies on contourite systems, the complexity and diversity of these sedimentary systems are still not fully understood and often underestimated. Their understanding requires comprehensive works integrating all scales from seismic architecture to microfacies. This paper focuses on a contouritic ridge located between 2000 m and 2500 m water depth on the Mozambique margin. Bathymetry, seismic data and piston cores collected during the PAMELA-MOZ3 cruise allow a multi-scale study from large depositional geometries to sedimentary facies. At the seismic scale, the contouritic ridge shows three stages of evolution with: (i) initiation and development of the drift/moat system; (ii) an intermediate stage with successive incisions and aggradations; and (iii) moat infill and drift erosion during the Plio-Quaternary. Plio-Quaternary deposits are composed of hemipelagic, turbiditic and contouritic facies filling the moat. Coarse-grained contouritic facies, dominated by planktonic foraminifera, are identified on the western flank of the ridge between the moat infill and the erosional area at the top of the ridge. They consist of condensed deposits, with sedimentation rate about 0.3 cm/ka, indicating a strong and stable bottom current that winnows away the fine-grained component. This facies could be present more generally in an intermediate position between erosion and depositional areas in contourite systems. At present, the contourite system is located at the transition depth between North Atlantic Deep Water and Antarctic Intermediate Water. Trajectories of bottom currents are complex and interact with sporadic turbidity currents and anti-clockwise eddies that participate in reshaping the sea floor morphology. Although Plio-Quaternary depositional geometries indicate the end of drift/moat development, the moat filling and drift erosion are also related to bottom currents and constitute atypical contouritic sedimentation.