TY - JOUR T1 - Pliocene and Pleistocene stratigraphic evolution of the western Niger Delta intraslope basins: A record of glacio-eustatic sea-level and basin tectonic forcings A1 - Chima,Kelvin Ikenna A1 - Gorini,Christian A1 - Rabineau,Marina A1 - Granjeon,Didier A1 - Do Couto,Damien A1 - Leroux,Estelle A1 - Hoggmascall,Nick AD - Sorbonne Université-ISTeP UMR 7193, F7500 Paris, France AD - Alex Ekwueme Federal University, Ndufu-Alike Ikwo, Ebonyi State, Nigeria AD - CNRS, UMR 6538, LGO (CNRS/UBO/UBS), Plouzane, France AD - IFPEN, Rueil-Malmaison, France AD - IFREMER, ZI Pointe du Diable, Plouzane,, France AD - Shell International, London, UK UR - https://doi.org/10.1016/j.gloplacha.2020.103355 DO - 10.1016/j.gloplacha.2020.103355 KW - Niger Delta KW - Intraslope basins KW - Pliocene KW - Pleistocene KW - Seismic stratigraphy KW - Allocyclic forcing KW - Eccentricity cycles N2 - Although climate proxy (δ18O) across the world ocean basins reveals that orbital forcing significantly controlled the Pliocene and the Pleistocene sediment deposition, and has been demonstrated in seismic and outcrop studies on the continental shelves of many margins, few or no seismic stratigraphic studies have investigated orbital forcing on deep-water sediment records. In this study, we combined detailed seismic stratigraphy and 3D geomorphological analysis of a high-resolution 3D seismic block in a detailed study of the stratigraphic evolution of the western Niger Delta intraslope basins over the last 5.5 Ma. Two mega seismic units named MSU 1 and MSU 2 were identified. The change in sedimentary architecture from (i) mass flows and turbidite sequences to (ii) hemipelagic and turbidite sequences at the MSU 1/MSU 2 transition coincides with a significant (x3) increase in sedimentation rates and a transition from dominant 400 ka eccentricity cycles (from 5.3 Ma-0.8 Ma) to dominant 100 ka eccentricity cycles, at the Middle Pleistocene Transition (MPT) (circa 0.8–0 Ma). The timing of these changes was estimated based on a detailed analysis of seismic facies succession, correlation of seismic markers with high-resolution sea-level and oxygen isotope curves, and estimation of sequence duration. Further changes in the sedimentary record, characterised by turbidite-dominated sequences at the lower part of MSU 1 to mixed mass flows and turbidite sequences at the upper part of MSU 1, were respectively correlated with changes that occurred in the early Pliocene (circa 4.9 Ma) and in the early Pleistocene (circa 2.6 Ma). The depositional sequence on the western Niger Delta intraslope basin is usually characterised by a falling stage erosional surface (FSES) at its base and top (sequence boundary), and by (i) basal MTDs/bypass facies (where preserved), (ii) turbidite feeder channels/aggrading or meandering channel levee complexes and/or MTDs (slides/slumps) and (iii) hemipelagic drapes that successively document the falling stage, lowstand to early transgressive and late transgressive to highstand transits of the shoreline. This seismic stratigraphic study demonstrates for the first-time sequence cyclicity associated with orbital (Milankovitch) forcing in the deep-water Niger Delta over the last 5.5 Ma. The Pliocene and Pleistocene sedimentary records of the western Niger Delta intraslope basins were controlled by interplay between allocyclic forcing linked to glacio-eustatic sea-level oscillations and basin tectonics associated with mobile shale movements, the latter being more prevalent from the early Pliocene to the MPT. If calibrated with high-resolution biostratigraphic data in future studies, this study could serve as a useful analogue for further studies in the Gulf of Guinea, equatorial Atlantic and other margins fed by large deltas. Y1 - 2020/12 PB - Elsevier BV JF - Global And Planetary Change SN - 0921-8181 VL - 195 ID - 76737 ER -