Seismic stratigraphic framework and depositional history for Cretaceous and Cenozoic contourite depositional systems of the Mozambique Channel, SW Indian Ocean

Abstract

This study describes previously unrecognized contourite depositional systems (CDSs) in the Mozambique Channel which constrain palaeoceanographic models for this area. The stratigraphic stacking patterns record nine seismic units (SU1 to SU9) separated by eight major discontinuities (a to h, oldest to youngest). Key seismic markers in CDS evolutionary history occur during Aptian-Albian (~122 Ma), late Cenomanian (94 Ma), early (38.2–36.2 Ma) and late (25–23 Ma) Oligocene, and early-middle Miocene (~17–15 Ma) epochs. These record onset (~122 to 94 Ma), growth (94 to 25–23 Ma), maintenance (25–23 to 17–15 Ma), and burial (17–15 Ma to the actual time) stages for CDSs. CDSs first develop during the onset stage which coincides with the opening and deepening of the African-Southern Ocean gateway (at 122 and 100 Ma, respectively). The growth stage, beginning in the late Cenomanian (94 Ma), correlates with the opening and deepening of the Equatorial Atlantic gateway. During the growth stage, two major shifts in sedimentary stacking pattern occur which coincide with palaeoceanographic changes during the early (38.2–36.2 Ma) and late (25–23 Ma) Oligocene. These in turn coincide with the onset and local enhancement of Antarctic water masses. CDS growth continued until the early-middle Miocene during the maintenance stage (~17–15 Ma). Most CDS growth ceased at the end of the maintenance stage. Circulation of the North Atlantic water mass into the Southern Hemisphere led to a deepening of Antarctic water masses in the area.