Lower Congo Research Articles

Turbidite facies identification and analysis using geophysical methods in the salt diapir domain of Lower Congo basin

This study applied geophysical methods to investigate the turbidite system developing over salt domes in the Lower Congo basin. As a rift basin, the Lower Congo basin experienced synrift, transition and post-rift tectonic movement. A series of evaporite deposits consisting largely of Aptian salts overlay the synrift half-grabens followed by thick post-rift sediment. The westward tilting triggered massive loading of Congo fan delta and initiated salt movement. In the study area, the major reservoirs are Oligocene and Miocene turbidite sands. The tectono–sedimentary interactions between Oligocene-Miocene deep-water depositional systems and salt-related structural topography can be observed through the salt structure and the deformation of turbidites. Later salt movement created a complex structure and either deformed the original setting of turbidite deposition or provided accommodation of the turbidite flow system. However, the complexity of salt structures and turbidite systems complicates the prediction of reservoir configuration and sedimentary facies in the study area. With high-resolution 3D seismic, we are able to study the sedimentary facies by employing geophysical methods that include seismic amplitude analysis, seismic waveform classification and spectral decomposition techniques. Our interpretations suggest that in the study area, the width of turbidite system ranges from 200 m to 4 km and the total thickness is up to 200 m. The turbidite channels trended from the northeast to the southwest during the Oligocene and turned westwards approximately 24° in the Miocene. Three typical sediment architectures are observed including distributary channel mouth lobe, confined turbidite complex with cut and fill channels and isolated individual channels, which would be the useful models for the reservoir evaluation over the active salt domes.

E&P Notes (June 2021)

E&P Notes (June 2021)

Cast netting new species: Integrative taxonomy of emDistichodus/em emnotospilus/em (Characiformes: Distichodontidae) discovers new species and overlooked areas of endemism in Central Africa.

Distichodus notospilus was described from the Ogooué River and is considered to occur throughout the Lower Guinea ichthyofaunal province and the western tributaries of the middle and lower Congo River. Recent expeditions in Equatorial Guinea collected D. notospilus specimens in the Mbini River drainage and the Mbia River; a small coastal river that is located between the Ntem and Mbini river drainages. Detailed morphological analyses and multilocus molecular analyses confirm that these two populations are distinct from one another. Topotypic populations of D. notospilus were included in the analyses and demonstrated that populations in the Mbini and Mbia rivers are distinct and these two new species are described herein. Distichodus microps sp. nov. is endemic to the Mbia River drainage and is distinguished from D. notospilus in having more scales along the lateral line (41, rarely 40 versus 37-39, rarely 40), a nearly inferior mouth versus subterminal in D. notospilus, a curved posterolateral margin of the opercle versus straight in D. notospilus, a smaller eye (56.7-80.4 versus 70.1-104.3 % of snout length), and a less prominent elongated spot at the base of the caudal fin. Distichodus mbiniensis sp. nov. is endemic to the upper Mbini River drainage and distinguished from D. notospilus in having more scales along the lateral line (41-42, rarely 40 versus 37-39, rarely 40), a much less prominent elongated dark spot at the base of the caudal fin, and a shorter dorsal fin (21.4-27.2 versus 22.7-34.2% standard length). Distichodus microps is distinguished from D. mbiniensis in having a shallower body (usually six scales from lateral line to the pelvic fin versus seven), fewer anal-fin rays (usually 12 total rays versus 13 or 14), a more inferior mouth, a deeper and longer caudal peduncle, a smaller eye, and differences in several features associated with the head. In addition to the two new species described this study also revealed potential undescribed diversity in the D. notospilus species complex in the Ntem River and Dja River (Congo R. basin) in Cameroon. The biogeography of these fishes in the rivers of Lower Guinea suggests that the Mbini River and smaller coastal rivers are overlooked areas of endemism. Studies of other reported widespread species will likely reveal additional diversity and further elucidate the processes promoting and maintaining freshwater diversity in Central Africa.

Pre-salt regional structure and its control for hydrocarbon accumulation in Lower Congo Basin from seismic and gravity data

In the present work, we utilize the processing and interpretation of both seismic and gravity data to clarify pre-salt regional structure pattern and further guide pre-salt exploration in Lower Congo Basin. Combining other available geologic and lithology data sets as well as a tectonic model, we present a new understanding of the pre-salt uplift and depression pattern of Lower Congo Basin. The results show a clear E-W distribution of the first-class structural units, namely, the inner rift zone, central uplift zone and outer rift zone, where the latter two parts are separated by the Atlantic hinge zone. The outer rift zone is characterized by a "two convex and three concave" high and depression pattern. The patterns of the pre-salt structure control the distribution of source rocks, reservoir and cap rock types, and also affect the combination and model of hydrocarbon accumulation. The key exploration area can be placed in the shallow water area on the land side of both the inner rift zone and the outer rift zone. The favorable exploration targets should be focused on fault-controlled blocks of the structural high horst. This study can provide the geophysical support for a new interpretation of the pre-salt seismic sequence, the strategic selection of pre-salt hydrocarbon and the next exploration deployment.

The optimistic utopia: sacrifice and expectations of political transformation in the Angolan Revolutionary Movement

The optimistic utopia: sacrifice and expectations of political transformation in the Angolan Revolutionary Movement

Detrital input quantification in lacustrine petroleum systems: An example of the pre‐salt source rocks from the Lower Congo Basin (Congo)

AbstractThis study describes an integrated workflow designed to quantify detrital input into lacustrine deposits in terms of regional extent and total organic carbon content. This workflow includes (a) organic geochemical data such as Rock Eval and palynofacies and (b) palaeogeographical maps. This workflow was applied to the immature Barremian source rocks from the Lower Congo Basin because of a large available data set describing a complex sedimentary record. From palynofacies analysis, it was demonstrated that lacustrine organic matter corresponds to a hydrogen index higher than 600 mg/g C whereas detrital input corresponds to a hydrogen index lower than 300 mg/g C. The range seen in the hydrogen index of between 300 and 600 mg/g C corresponds to mixtures of organic matter. The correlation between the hydrogen index and detrital content was then applied to 50 wells which allowed the extent of detrital input to be mapped at local and regional scales. The geochemical data were plotted on high‐resolution palaeogeographic maps for four stratigraphic intervals, BA2, BA2‐BA3, BA3‐PN and BA3‐PI. Results confirm the periodic presence of lacustrine turbiditic systems allowing strong detrital inputs into the palaeolake under the tropical palaeoclimate, especially in the BA2‐BA3 and BA3‐PI intervals. These inputs of continental‐derived organic material degrade the quality and richness of the lacustrine source rock leading to a decrease of the initial hydrogen index values. These detrital influxes were related to coastal rivers whereas, in the deepest parts of the basin, the autochthonous organic matter is well‐preserved and not diluted, which allowed the deposition of exceptional source rocks especially during the BA2 and BA2‐BA3 intervals. All of these geochemical diagnostics are consistent with available palaeogeographic maps. This study demonstrated the importance of integrating geochemical data into the palaeo‐reconstruction of the source rock depositional environment. It enables palaeogeographic maps to be constrained in terms of both detrital input and preservation at both regional and local scales for a given source rock.

Evolution and controlling factors of the gravity flow deposits in the Miocene sequence stratigraphic framework, the Lower Congo—Congo Fan Basin, West Africa

To understand the evolution of the Miocene gravity flow deposits in the Lower Cong—Congo Fan Basin, this paper documents the Miocene sequence stratigraphic framework, the depositional characteristics and the controlling factors of the gravity flow system. Based on the establishment of high-resolution sequence stratigraphic framework, lithofacies characteristics and sedimentary units of the gravity flow deposits in the region are identified by using seismic, well logging and core data comprehensively, and the sedimentary evolution process is revealed and the controlling factors are discussed. The Miocene can be divided into four 3rd-order sequences (SQ1—SQ4). The gravity flow deposits mainly include siliciclastic rock and pelite. The main sedimentary units include slumping deposits, mass transport deposits (MTD), channel fills, levee-overbank deposits, and frontal lobes. In the Early Miocene (SQ1), mainly gull-wing, weakly restricted to unrestricted depositional channel-overbank complexes and lobes were formed. In the early Middle Miocene (SQ2), W-shaped and weakly restricted erosional-depositional channels (multi-phase superposition) were subsequently developed. In the late Middle Miocene (SQ3), primarily U-shaped and restricted erosional channels were developed. In the Late Miocene (SQ4), largely V-shaped and deeply erosional isolated channels were formed in the study area. Climate cooling and continuous fall of the sea level made the study area change from toe of slope-submarine plain to lower continental slope, middle continental slope and finally to upper continental slope, which in turn affected the strength of the gravity flow. The three times of tectonic uplifting and climate cooling in the West African coast provided abundant sediment supply for the development of gravity flow deposits. Multistage activities of salt structures played important roles in redirecting, restricting, blocking and destroying the gravity flow deposits. Clarifying the characteristics, evolution and controlling factors of the Miocene gravity flow deposits in the Lower Congo—Congo Fan Basin can provide reference for deep-water petroleum exploration in this basin.

Dynamika ruchów mesjanistycznych w Afryce na przykładzie ludności Basenu Dolnego Konga

Artykuł dotyczy kościołów i grup religijnych, które powstawały w Afryce na bazie chrześcijaństwa w XX w. Przykładem jest tu religijność ludności zamieszkującej rejon Basenu Dolnego Konga. Początkowo aktywność religijna była tu wyrazem protestu przeciw segregacji rasowej i wyzyskowi kolonialnemu. Powstające kościoły niezależne były często kuźnią rodzących się nacjonalizmów. Ożywiane duchem mesjańskim przy­rzekały lepszą przyszłość wraz z uzyskaniem niepodległości. Z czasem kościoły te się zinstytucjonalizowały, a państwa uzyskały niepodległość, ale nie oznaczało to obiecanej świetlanej rzeczywistości. Wręcz przeciwnie. Kryzys lat osiemdziesiątych i dziewięć­dziesiątych XX w. spowodował wzrost ubóstwa i zakwestionowanie dotychczasowego rozwoju. Na tym podatnym gruncie powstawały nowe ruchy religijne o charakterze neopentekostalnym, które głoszą teologię dobrobytu i praktyczne zbawienie, w ramach którego możliwe jest wyjście z biedy przez osobiste nawrócenie i zaangażowanie religij­ne. W związku z wielką popularnością tych ruchów, niezależne kościoły afrykańskie zmuszone są do znacznych adaptacji.

Classical Biomarker and Quantitative Extended Diamondoid Analysis Fingerprints for Crude Oils from Deepwater Developments in Block 17, Lower Congo Basin, Angola.

The organic geochemistry of six oil samples from the offshore Block 17 (Lower Congo Basin, northwestern Angola) was studied by a combination of classical biomarker and extended diamondoid analyses to elucidate source rock facies, the extent of biodegradation, and thermal maturity. Based on molecular data, oils are interpreted as depicting a mixture of two pulses of hydrocarbon generation probably from the Bucomazi and Malembo formations. Geochemical results also gave evidence of mixing of a lacustrine siliciclastic-sourced oil charge and a second more terrestrially derived oil type in the samples analyzed. A single genetic oil family was identified through hierarchical cluster analysis; however, two groups of oils were identified on the basis of their biodegradation levels using the Peters/Moldowan scale. Lower and upper Malembo oils have a slight depletion and a notable absence of n-alkanes, suggesting PM levels of 1 and 2, respectively. Most molecular maturity parameters of the oil samples suggest a maturity level equivalent to the onset of the peak of the oil generative window.

Characterization of fossils and typomorphic minerals and its implications for source rocks in the Lower Congo Basin

Characterization of fossils and typomorphic minerals and its implications for source rocks in the Lower Congo Basin

Health in a Fragile State: Science, Sorcery, and Spirit in the Lower Congo. John M. Janzen, Madison: University of Wisconsin Press, 2019, 288 pp.

Health in a Fragile State: Science, Sorcery, and Spirit in the Lower Congo. John M. Janzen, Madison: University of Wisconsin Press, 2019, 288 pp.

Genomic Analysis of the Only Blind Cichlid Reveals Extensive Inactivation in Eye and Pigment Formation Genes.

Trait loss represents an intriguing evolutionary problem, particularly when it occurs across independent lineages. Fishes in light-poor environments often evolve “troglomorphic” traits, including reduction or loss of both pigment and eyes. Here, we investigate the genomic basis of trait loss in a blind and depigmented African cichlid, Lamprologus lethops, and explore evolutionary forces (selection and drift) that may have contributed to these losses. This species, the only known blind cichlid, is endemic to the lower Congo River. Available evidence suggests that it inhabits deep, low-light habitats. Using genome sequencing, we show that genes related to eye formation and pigmentation, as well as other traits associated with troglomorphism, accumulated inactivating mutations rapidly after speciation. A number of the genes affected in L. lethops are also implicated in troglomorphic phenotypes in Mexican cavefish (Astyanax mexicanus) and other species. Analysis of heterozygosity patterns across the genome indicates that L. lethops underwent a significant population bottleneck roughly 1 Ma, after which effective population sizes remained low. Branch-length tests on a subset of genes with inactivating mutations show little evidence of directional selection; however, low overall heterozygosity may reduce statistical power to detect such signals. Overall, genome-wide patterns suggest that accelerated genetic drift from a severe bottleneck, perhaps aided by directional selection for the loss of physiologically expensive traits, caused inactivating mutations to fix rapidly in this species.

Spatial and temporal variations in minibasin geometry and evolution in salt tectonic provinces: Lower Congo Basin, offshore Angola

AbstractIn passive margin salt basins, the distinct kinematic domains of thin‐skinned extension, translation and contraction exert important controls on minibasin evolution. However, the relationship between various salt minibasin geometries and kinematic domain evolution is not clear. In this study, we use a semi‐regional 3D seismic reflection dataset from the Lower Congo Basin, offshore Angola, to investigate the evolution of a network of minibasins and intervening salt walls during thin‐skinned, gravity‐driven salt flow. Widespread thin‐skinned extension occurred during the Cenomanian to Coniacian, accommodated by numerous distributed normal faults that are typically 5–10 km long and spaced 1–4 km across strike within the supra‐salt cover. Subsequently, during the Santonian–Paleocene, multiple, 10–25 km long, 5–7 km wide depocentres progressively grew and linked along strike to form elongate minibasins separated by salt walls of comparable lengths. Simultaneous with the development of the minibasins, thin‐skinned contractional deformation occurred in the southwestern downslope part of the study area, forming folds and thrusts that are up to 20 km long and have a wavelength of 2–4 km. The elongate minibasins evolved into turtle structures during the Eocene to Oligocene. From the Miocene onwards, contraction of the supra‐salt cover caused squeezing and uplift of the salt walls, further confining the minibasin depocentres. We find kinematic domains of extension, translation and contraction control the minibasin initiation and subsequent evolution. However, we also observe variations in minibasin geometries associated with along‐strike growth and linkage of depocentres. Neighbouring minibasins may have different subsidence rates and maturity leading to marked variations in their geometry. Additionally, migration of the contractional domain upslope and multiple phases of thin‐skinned salt tectonics further complicates the spatial variations in minibasin geometry and evolution. This study suggests that minibasin growth is more variable and complex than existing domain‐controlled models would suggest.

Post‐stack impedance blocky inversion based on analytic solution of viscous acoustic wave equation

ABSTRACTThe conventional impedance inversion method ignores the attenuation effect, transmission loss and inter‐layer multiple waves; the smooth‐like regularization approach makes the corresponding impedance solution excessively smooth. Both fundamentally limit the resolution of impedance result and lead to the inadequate ability of boundary characterization. Therefore, a post‐stack impedance blocky inversion method based on the analytic solution of viscous acoustic equation is proposed. Based on the derived recursive formula of reflections, the 1D viscous acoustic wave equation is solved analytically to obtain zero‐offset full‐wave field response. Applying chain rule, the analytical expression of the Fréchet derivative is derived for gradient‐descent non‐linear inversion. Combined with smooth constraints, the blocky constraints can be introduced into the Bayesian inference framework to obtain stable and well‐defined inversion results. According to the above theory, we firstly use model data to analyse the influence of incompleteness of forward method on seismic response, and further verify the effectiveness of the proposed method. Then the Q‐value sensitivity analysis of seismic trace is carried out to reduce the difficulty of Q‐value estimation. Finally, the real data from Lower Congo Basin in West Africa indicate that the proposed approach provide the high‐resolution and well‐defined impedance result. As a supplement and development of linear impedance inversion method, the non‐linear viscous inversion could recover more realistic and reliable impedance profiles.

Historical museum collections help detect parasite species jumps after tilapia introductions in the Congo Basin

This study highlights the value of museum collections in invasion biology. It focuses on introduced tilapias, Oreochromis niloticus and Coptodon rendalli in the Congo Basin and their monogenean (Platyhelminthes) gill parasite fauna. O. niloticus was introduced throughout the Congo Basin while C. rendalli was introduced into the Lower Congo, but is native to the Middle and Upper Congo. In order to study the impact of these stocking events on the native parasite community we investigate the co-introduction and host switching of their parasites. Post-introduction material is compared with pre-introduction samples from museum collections of 5 native tilapias in the Congo Basin. Nine of the known parasites of O. niloticus were co-introduced, while one, Cichlidogyrus rognoni, is missing and possibly not established. In contrast, no parasite species were found co-introduced with C. rendalli into the Lower Congo. The parasite fauna of Tilapia sparrmanii shared no species with O. niloticus. Oreochromis mweruensis shared five species with O. niloticus, but these were also found on the pre-introduction samples, and are considered native to both hosts. We report three putative host switches: Cichlidogyrus sclerosus and Cichlidogyrus tilapiae to Coptodon tholloni in the Lower Congo Basin and Gyrodactylus nyanzae to C. rendalli in the Upper Congo.

Mitogenomic characterization and systematic placement of the Congo blind barb Caecobarbus geertsii (Cypriniformes: Cyprinidae)

This study presents the first complete mitochondrial genome (mitogenome) of Caecobarbus geertsii, the Congo blind barb, a cave-dwelling, CITES-protected, cyprinid fish endemic to the Lower Congo basin (DRC). The length of the circular mitogenome is 16,565 base pairs. The 13 protein coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes are similar in position and direction to those of other members of the family Cyprinidae. Phylogenetic analyses including 28 complete mitogenomes from representatives of the subfamily Smiliogastrinae (Cyprinidae), showed that Caecobarbus was nested within a clade including representatives of the genus Enteromius. The data presented in this study provide information on the molecular identification and classification of this threatened species. The results further suggest the need for a taxonomic revision of the genus Enteromius.

Capacity Building in the Congo Basin: Rich Resources Requiring Sustainable Development

The Congo Basin is a unique freshwater ecosystem supporting hundreds of millions of people and a crucial part of regulating Earth’s water cycle. Increasing international attention on its resource potential brings worrying pressures to this understudied region. Equitable collaboration is the key to understanding this complex, interconnected system and enabling its sustainable development.

Facies and architecture of the SCIc formation (Schisto-Calcaire Group), Republic of the Congo, in the Niari-Nyanga and Comba subbasins of the neoproterozoic west Congo basin after the marinoan glaciation event

The Neoproterozoic Schisto-Calcaire Group (630 to ca. 580 Ma) was deposited on an extensive carbonate shelf in the margin of the Congo Craton in the Niari-Nyanga and Comba subbasins (Gabon and Republic of the Congo). It consists of three carbonate-dominated subgroups (SCI to SCIII, up to 1300 m-thick) recording relative sea-level changes. The SCIc Formation, at the upper part of the SCI Subgroup, is a carbonate succession of meter-scale shallowing-upward cycles, composed of a standard sequence of 7 facies grouped in 5 facies associations recording the evolution of a marine ramp from distal carbonate muds and giant stromatolitic bioherms (F1–F2) and extensive ooid shoals (F3), to proximal settings submitted to evaporation near a sabkha (F7). Fifth-order ‘meter-scale’ (or elementary parasequences) packages are grouped into fourth-order sequences (parasequence sets), which are not correlative in the whole basin. Two categories of fifth-order elementary parasequences are recognized, on the basis of physical bounding surfaces: (i) subtidal cycles bounded by marine flooding surfaces across which subfacies deepen; and (ii) peritidal cycles bounded by subaerial exposure surfaces. These cycles are the result of the interplay of relative sea-level changes due to eustatic variations related to periodic extensional tectonic events affecting the whole basin. The Niari-Nyanga and Comba subbasins experienced basin tectonics in the general context of the rifting of Rodinia creating changes of relative sea-level in the different parts of the shelf. The SCIc cycles are enclosed into a third-order sequence with two major transgressive-regressive phases, related to the deposition of the SCI Subgroup. The most typical sedimentologic feature of the SCIc Formation is the deposition of giant stromatolitic bioherms (stacked up to 20 m) topped by ooid shoals (up to 75 m thick) deposited during high systems tract prograding and forced regressive systems tract phases that ended with a lowstand systems tract phase with evaporitic and karstic conditions at the top of the SCIc Formation. The elementary parasequences and parasequence sets are probably the result of the migration of lateral environments related to the variation of the energy in relation to tectonic setting. As a result, a regional sea-level increase is for the first time highlighted in transgressive systems tract phase (composed of microbial induced sedimentary structures Facies) in the lower part of the SCIc Formation. The third-order succession can be followed more than 100 km in the Republic of the Congo and several hundred meters from South of Gabon to the Lower Congo in the Democratic Republic of the Congo. Tentative detailed sequence stratigraphy correlations between both Congo's highlight the role of tectonics affecting both areas.

Hidden species diversity in Marcusenius moorii (Teleostei: Mormyridae) from the Congo Basin.

New collections from the Yangambi Biosphere Reserve (YBR) and Okapi Wildlife Reserve (OWR) revealed the presence of two groups of specimens similar to, but different from Marcusenius moorii. To study both these groups, an integrated morphological and genetic (mtDNA, cytb) approach was used. This study revealed that one of the two groups is conspecific with Marcusenius lambouri, a junior synonym of M. moorii, which is herein revalidated, with M. moorii longulus as its junior synonym. Marcusenius lambouri differs from M. moorii by a higher number of lateral line scales (44-46 vs. 40-43), a shorter pectoral-fin length (14.6-19.9 vs. 20.3-25.2% standard length; LS ) and a more elongated body due to a usually shallower middle body depth (19.8-26.5 vs. 26.3-35.9% LS ). The other group revealed to be a new species for science, Marcusenius verheyenorum, which can be distinguished from its congeners with eight circumpeduncular scales by the following unique combination of characters: a rounded head with a terminal mouth; a short and deep caudal peduncle (middle caudal-peduncle depth, 44.9-54.6% caudal-peduncle length; LCP ), a deep body (middle body depth, 27.7-34.2% LS ), 38-43 scales on the lateral line, 40-41 vertebrae, 20-21 dorsal-fin rays and 26 anal-fin rays. Some specimens previously attributed to M. moorii were examined and reassigned to M. lambouri or M. verheyenorum. As a result, M. moorii and M. lambouri occur in sympatry in the middle Congo Basin, with the distribution area of M. moorii still further extending into the lower Congo Basin. Instead, the distribution of M. verheyenorum is limited to some right bank tributaries of the upstream part of the middle Congo Basin. Two museum records from the Lilanda River (YBR), collected in the 1950s and previously identified as M. moorii, were re-identified as belonging to the new species, M. verheyenorum. However, the species now seems locally extinct in that region, which reflects the significant anthropogenic effects even within this reserve.

Deep-water channels in the lower Congo basin: Evolution of the geomorphology and depositional environment during the Miocene

Abstract Deep-water channel systems are an important component of the “source to sink” system from continental slope to deep-sea basin. They are also the critical reservoir type in deep-water hydrocarbon exploration. The study of geomorphology evolution, filling processes and controlling factors of the Miocene deep-water channel in the Lower Congo Basin is conducive to deepening our understanding of basin dynamics, and to improving the prediction accuracy of deep-water reservoirs. Based on 3D seismic data, cores, thin sections, well logging data, we study the Miocene seismic stratigraphic characteristics, deep-water sedimentary units, lithofacies and channel types. Using the techniques and means of seismic geomorphology, we discuss the occurrence, development, recession and extinction processes of channel complexes and controlling factors. The Miocene was divided into seven 3rd-order sequences. Each 3rd-order sequence is subdivided into two (lower/upper) seismic stratigraphy units, with initial flooding surface (FS) as the separated boundary. The seismic characteristics of the lower/upper unit suggest the occurrence of alternating turbidite/hemipelagic sedimentary units. Seismic units such as erosional surface, filling channel, levee, lobe, MTD and background slope deposits are described. Fifteen deep-water lithofacies are identified and they are determined to be composed of clay, silt, fine-coarse sand, gravel, and conglomerate. The deep-water channels in the study area are interpreted four types: single-stage erosional channel, single-stage aggradational channel, vertical aggradational channel complexes and lateral migration channel complexes. The different types of channel are the results of interaction of flow energy and accommodation space. On this basis, we propose that tectonic uplift is the driving force for the formation of the deep-water sandy channel system, and that high frequency sea-level fluctuation in West Africa controls the development of third-order sequences and restricts the scale of the deep-water sandstone accumulation. In addition, the avulsion processes controlled by climate variations are the main factors to influence channel complex filling process.