Postrift depositional evolution and sequence stratigraphy from offshore subsurface data of the Kribi-Campo subbasin (Cameroon, West African margin)

Abstract

Using 2D seismic data and well logs from the Kribi-Campo subbasin in the south Cameroon margin, we have analyzed the postrift succession with the aim of deriving a chronostratigraphic chart and identifying stratigraphic traps. The Kribi-Campo subbasin related to the rifting between Africa and South America could be divided into a structurally complex eastern depocenter and a relatively less disturbed western depocenter in which a break-up unconformity approximately 107.5 Ma underlined the beginning of postrift history. We have used the modern concepts of sequence stratigraphy to identify and characterize seven second-order (SS1, SS2, SS3, SS4, SS5, SS6, and SS7) sequences and one third-order (SS8) sequences grouped into three megasequences (A, B, and C) from Albian to Recent. Sequence 1 (Albian-Cenomanian) was characterized by a retrogradation overlying a lowstand progradational pattern. The SS2 (Campanian-Maastrichtian) and SS3 (Maastrichtian) sequences were deposited during a highstand normal regression. From Paleocene to Eocene, the deposition of sequences SS4–SS5 was controlled by the development of submarine fan turbiditic system related to a forced regression of coastline. From the Middle Miocene to Recent age, the SS6, SS7, and SS8 sequences have been characterized by the development of sigmoidal-oblique clinoforms of a deltaic system well observed in the northern part of the study area. We have studied a new undocumented phase of forced regression of Mio-Pliocene in age within the postrift sequence SS7. The forced regression phases are associated with the Paleogene and Neogene uplift. Relative sea-level curves were constructed and compared with the existing published curves. The processes involved in the formation of these sequences were interpreted as a combination of tectonics, sediment supply, and sea-level changes. Potential reservoirs embedded within the sequences include channel fill, shingled turbidites, slope fan, and basin-floor fan complex.

Striations at The Base of The Paleo-Fan and Channel Revealed by 3D Seismic Data, Offshore Cameroon

“…Basin stratigraphy from Paleocene to Pleistocen of Kribi-Cambo Basin. Stratigraphy of the basin is interpreted from 3D seismic data with the inference age from Gulf of Guinea and 2D seismic interpretation of Kribi-Cambo Basin (Lawrence et al, 2002;Iboum Kissaaka et al, 2016). Due to the lack of well data in the basin, depth conversion assumes a similar lithological composition to the Rio-Muni Basin, and a Vp velocity of 1,850 m/s has been used for the Tertiary sediments (Turner, 1995).…”

Distribution of Mid‐deeply Buried Sand‐bodies and their Hydrocarbon Significance at Basin Margins: Case Study of the Paleogene in the Eastern Liuzan Area of the Nanpu Sag, Bohai Bay Basin, China

“…Sequence stratigraphy has gradually become a useful tool for studying sedimentary reservoir distribution within the hydrocarbon industry (Tinker, 1996;Lin et al, 2001;Zhu et al, 2008;Iboum Kissaaka et al, 2016;Rivera et al, 2018). The three-order sequence stratigraphic boundary was determined based on the unconformity The study interval is Es 3 reflection characteristics of the slope area and its corresponding conformity reflection characteristics of the non-slope area via seismic data.…”

Seismic Geomorphology of a Late Cretaceous Turbidite Channel system in Deepwater Kribi/Campo sub-basin, offshore Cameroon

“…The post-rift sequence in the study area is characterized by sand-rich turbidity channel belts and basin floor to toe-of-slope fans (Wornardt, 1999;Sterling, 2010;Le, 2012;Iboum et al, 2016;Loule et al, 2018;Yugye et al, 2021) (Fig. 2).…”

“…In the more proximal settings (i.e., east of Kribi-Campo High), there are multiple submarine incisions of several kilometres wide and some amalgamated cut-and-fill submarine channel complexes downslope and parallel to present-day shelf-break for most of the Paleocene section (Wornardt, 1999;Le, 2012;Iboum et al, 2016). The late Eocene-early Oligocene tectonic event facilitated a relative sea-level fall, responsible for the widespread erosion and non-deposition in the deep-water of Douala Basin (Wornardt, 1999;Helm, 2009;Mvondo, 2010;Iboum et al, 2016;Ngo et al, 2018;Le, 2021) (Fig. 2).…”

“…The Kribi/Campo sub-basin, which is a component of the northern Douala/Kribi-Campo Basin, hosts the South Sanaga and Kribi oil fields in deep-water turbidite sediments (Pauken et al, 1991;Pauken, 1992;Nguene et al, 1992;Ackerman et al, 1993;Tamfu et al, 1995;Brownfield and Charpentier, 2006;Ndonwie, 2007). However, in contrast to the well-studied submarine channels and their implications for hydrocarbon exploration in the West African basins (e.g., Niger Delta, Congo, and Gabon), those in the Kribi/Campo subbasin are poorly understood in terms of their architectural elements, morphological variations and factors controlling the distribution of sands (see Iboum et al 2016;Loule et al, 2018;Yugye et al, 2021).…”