Mesozoic and Early Cenozoic sediment influx in the Mozambique Basin

Mozambique Basin is one of the oldest rifted sedimentary basins developed along the eastern African margin in Jurassic times. The basin has a continuous record of sediments since Jurassic when Antarctica separated from Africa. The primary objectives of this study were to extend the regional stratigraphic framework north of the Zambezi Delta and review early developments in the Mozambique basin. Nine Multi-Channel seismic reflection profiles are used to extend the regional stratigraphy in to deeper basin. We identify six major stratigraphic units that correlate to Jurassic, Early Cretaceous, Late Cretaceous, Paleogene, Neogene and Quaternary. Mesozoic sedimentation rates of 3-5 cm/kyr are observed in the deeper basin and 1-2 cm /kyr during Paleogene (neither compensated for compaction). Presence of shale from neighbouring wells imply a restricted circulation in the basin until mid-Cretaceous. Mesozoic sediments have a high velocity that exceed 4.5 km/s with an exception of a distinct low-velocity zone of 3.7 km/s in mid-Cretaceous that may indicate undercompacted overpressured shales. Albeit a smaller catchment area of the proto-Zambezi until Miocene, higher sedimentation rate in Late Cretaceous can be attributed to rapid denudation of the African continent after a major tectonic uplift episode at approximately 90 Ma. Increased sediment influx into the basin from the Zambezi in Late Cretaceous resulted in the formation a submarine delta fan lobe progressing into the Mozambique Channel around the northern periphery of Beira High. Strong north-south bottom currents commenced within the channel in Late Cretaceous that forced the aggradation of sediments of the submarine fan lobe on the southern flank. In addition, we observe several current-controlled drift bodies in the deeper basin that are influenced by the north-south bottom current. Low sedimentation rate in Paleogene is attributed to relative quiet tectonic phase onshore and erosion during global marine regression in mid-Oligocene