Pliocene and Pleistocene stratigraphic evolution of the western Niger Delta intraslope basins: A record of glacio-eustatic sea-level and basin tectonic forcings

https://doi.org/10.1016/j.gloplacha.2020.103355Get rights and content

Highlights

  • Seq. cycles linked to the Milankovitch cycles are recorded regionally on the Niger Delta slope.

  • The early Pliocene-mid Pleist. (5.5–0.8 Ma) is dominated by 400 ka eccentricity sequences.

  • The mid Pleist.-present (0.8–0 Ma) is dominated by 100 ka eccentricity sequences.

  • Increase in sedimentation rates at the MPT facilitated the preservation of the 100 ka sequences.

  • Glacio-eustatic and shale tectonic forcings controlled the Pliocene and Pleistocene stratigraphy.

Abstract

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.

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.

.

Introduction

Deep-water sediments are important archives of the Earth's history not only because they record past climatic, geodynamic, environmental and hydrodynamic changes (e.g. Burbank, 1992; Molnar, 2004; Catuneanu, 2006; Posamentier and Kolla, 2003; Zecchin et al., 2010), but also because they host viable hydrocarbon fields (see review in Morley et al., 2011). Understanding the complex interplay between allocyclic (e.g. eustasy, tectonics, climate and indirectly sediment supply), and autocyclic (e.g. channel avulsion) or regional forcings (e.g. delta lobe switching, shale tectonics etc.), is critical for interpretation of the evolution of deep-water sedimentary systems (e.g. Elliott, 1975; Jervey, 1988; Posamentier et al., 1988; Pulham, 1989; Einsele et al., 1991; Wiener et al., 2010; Miall, 2010; Morley et al., 2011; Catuneanu et al., 2011).

The Pliocene and Pleistocene are ideal time intervals for this kind of study because eustasy and climate proxies (δ18O) are well constrained and show significant variations both in amplitude and frequency (e.g. Ruddiman et al., 1989; Imbrie et al., 1993; Bassinot et al., 1994; Leroy et al., 1999; Shackleton, 2000; Lisiecki and Raymo, 2005; Miller et al., 2005; Gibbard et al., 2010; Gibbard and Lewin, 2016; Raymo et al., 2018). Published climate proxies across the worlds' ocean basins show that the Pliocene and Pleistocene were controlled by orbital forcing (Milankovitch cycles) of three major periods namely: (i) precession (23 ka), (ii) obliquity (41 ka), and (iii) eccentricity (400 and 100 ka) (Lisiecki and Raymo, 2007). The early Pliocene from (5.3 Ma) to the early Pleistocene was dominated by obliquity cycles (41 ka), while the middle Pleistocene (circa 1.4 Ma) to the present was dominated by eccentricity (400–100) (Head and Gibbard, 2015a, Head and Gibbard, 2015b; Gibbard et al., 2014; Gibbard and Lewin, 2016). Although the switch to the eccentricity cycles is poorly understood and a transition period from 1.4 to 0.4 Ma was suggested by Head and Gibbard, 2015a, Head and Gibbard, 2015b, and Gibbard and Lewin (2016), a marked change to increasingly severe glacial cycles, the so-called ‘0.8 Ma event’ (Lisiecki and Raymo, 2007; Head and Gibbard, 2015a, Head and Gibbard, 2015b) or ‘0.9 Ma’ (Miller et al., 2005; Eldefield et al., 2012), is usually interpreted as the Middle Pleistocene Transition (MPT).

Sedimentary records all over the world show the imprint of tectonic, climatic and glacio-eustatic cycles of different orders (Haq et al., 1987). Fourth-order climate cycles lasting 400 ka have been reported during the Pliocene e.g. on the continental shelf offshore Foz do Amazonas Basin (Brazil), with incised valleys, slope canyons and mass wasting (Gorini et al., 2014). During the Pleistocene, fifth-order glacio-eustatic sea-level changes with 100 ka periodicity are also well documented with marked shoreline progradation on the shelf and increased deep-water sedimentation during glacials e.g. in the Mediterranean Sea over the last 500 ka (Rabineau et al., 2006; Ridente et al., 2008; Lafosse et al., 2018). During the Pliocene, sediment architecture in the Mediterranean Sea does not appear to be much imprinted by the 400 ka cycles as shown in seismic (Rabineau et al., 2014) and numerical simulations (Leroux et al., 2014), probably because of an anomaly in accommodation created by the erosion of the entire margin after the Messinian Salinity Crisis. 100-ka glacio-eustatic cycles have also been described worldwide e.g. offshore Alaska (Gulick et al., 2015), in the Gulf of Mexico (Galloway, 2001) and the Bengal fan (Weber et al., 1997).

In the eastern Niger Delta, Jermannaud et al. (2010) and Rouby et al. (2011), documented a transition from global climate-controlled sequences from circa 4–2.5 Ma to sediment supply-controlled sequences from 2.5 Ma to the present. These authors also demonstrated a general progradation and an increase in sedimentation rates from 4 to 2.5 Ma, followed by a retrogradation and a decrease in sedimentation rates over the last 2.5 Ma. Additionally, Riboulot et al. (2012), showed that eccentricity forcing of 100 ka periodicities has controlled the stratigraphic evolution of the eastern Niger Delta continental shelf over the last 0.5 Ma.

In the western Niger Delta slope, where the present study was conducted (Fig. 1), Jobe et al., 2015, Jobe et al., 2016; red box in Fig. 1A, D), linked changes in sedimentation rates during the last 130 ka (MIS 5e to the present) to glacial/interglacial cycles with increased sedimentation rates during the lowering of the sea level (MIS3 and MIS2) and an overall reduction in sedimentation during a rapid post-glacial sea-level rise associated with the Meltwater pulse 1A at 14 ka. Earlier studies e.g. Lézine et al. (2014); Weldeab et al. (2011); Collins et al. (2014); Govin et al. (2014) and Armitage et al. (2015), linked the increase in sedimentation rates in the Gulf of Guinea during the Quaternary to the West African Monsoon. A recent high-resolution, 3D seismic and sequence stratigraphic study of the western Niger Delta slope (yellow box in Fig. 1A, C, D, E) by Chima et al. (2019, dated the Neogene stratigraphic record from the Burdigalian (18.5 Ma) to the late Miocene (5.5 Ma), and described interactions between mobile shale and erosional submarine channel over the last 5.5 Ma. However, the lack of biostratigraphic data for the Pliocene and Pleistocene poses a challenge to constraining the timing of major changes in sedimentary records.

Despite the above-mentioned studies of the Pliocene and Pleistocene sedimentary records in the Niger Delta, no study has investigated its control by orbital forcings from the late Messinian (5.5 Ma) to the present. Hence, the objective of this paper is to perform a detailed analysis of the stratigraphic evolution of the western Niger Delta intraslope basins over the last 5.5 Ma with a view to (i) proposing a sequence stratigraphic framework for the Pliocene and Pleistocene intervals; and (ii) investigating their control by orbital forcings.

The Niger Delta is an ideal laboratory to study climate stratigraphy and slope depositional processes because it is located on a passive margin where the imprints of regional/global climate dynamics, sea-level variation, gravity-tectonics, drainage evolution and sediment supply are well imaged on high-resolution 3D seismic reflection data.

Section snippets

Regional setting

The Cenozoic Niger Delta is located in the Gulf of Guinea on the equatorial Atlantic margin of West Africa (Fig. 1A). The delta is the twelfth largest petroleum province in the world (Tuttle et al., 1999). It covers an area of ~140,000 km2 with a maximum sediment thickness of ~12 km (Allen, 1965; Evamy et al., 1978; Doust and Omatsola, 1990). The Niger Delta is divided into the Eastern and the Western lobes by a Cretaceous basement high [the Charcot Fracture Zone (CFZ)] (Corredor et al., 2005;

Dataset

We used high-resolution 3D seismic data and lithologic logs from five boreholes (see Fig. 1A, D, E), to study the Pliocene and the Pleistocene stratigraphic evolution of the western Niger Delta.

Seismic facies analysis

The Pliocene and Pleistocene stratigraphy of the western Niger Delta intraslope basins were subdivided into two mega seismic units named MSU 1 and MSU 2, based on the observed changes in seismic geometries and depositional environments. MSU 1 and MSU 2 correspond to Unit 6 and Unit 7 respectively in Chima et al. (2019). Although a detailed seismic facies analysis of the study area was presented in Chima et al. (2019) (Fig. 1A, C, D, E; 2A), the present study sheds more light on facies

Discussion

We discuss the Pliocene and Pleistocene stratigraphic evolution of the western Niger Delta intraslope basins over the last 5.5 Ma in relation to allocyclic (glacio-eustatic) sea-level and basin tectonic forcings, and propose a deep-water depositional model.

Conclusions

Detailed seismic stratigraphy and 3D geomorphological analysis of high-resolution 3D seismic data over the Pliocene and Pleistocene stratigraphic record of the western Niger Delta intraslope basins, showed that:

  • 1.

    Glacio-eustatic sea-level changes since the last 5.5 Ma are recorded at regional scale in the intraslope basins of the western Niger Delta.

  • 2.

    The depositional sequence in the intraslope basins of the western Niger Delta is generally defined by the falling stage erosional surface (FSES) at

Declaration of Competing Interest

I, Kelvin Ikenna Chima, wish to state clearly that I have dully acknowledged the donor of the dataset used in this study (Shell Nigeria) and also the sponsor, Petroleum Technology Development Fund (PTDF) of the Federal Republic Nigeria. I also wish to clearly state that there is no conflict of interest in this study.

Acknowledgments

We thank the Federal Republic of Nigeria for sponsoring the PhD of Kelvin Ikenna Chima through the Petroleum Technology Development Fund (PTDF) Scholarship Programme. We are grateful to Shell Nigeria not only for providing the data used in this study but also for permission to publish it. PTDF provided the computer workstation used in this study. Many thanks to Schlumberger for providing Petrel () software, which we used to interpret the data. The first author would like to thank the

References (95)

  • A.S. Goudie

    The drainage of Africa since the Cretaceous

    Gemorphology

    (2005)
  • K Graue

    Mud volcanoes in deep-water Nigeria

    Marine and Petroleum Geology

    (2000)
  • L. Hansen et al.

    Submarine channel evolution, terrace development, and preservation of intra-channel thin-bedded turbidites: Mahin and Avon channels, offshore Nigeria

    Mar. Geol.

    (2017)
  • M.J. Head et al.

    Early-Middle Pleistocene transitions: Linking terrestrial and marine realms

    Quat. Int.

    (2015)
  • P. Heiniö et al.

    Knickpoint migration in submarine channels in response to fold growth, western Niger Delta

    Mar. Petrol. Geol.

    (2007)
  • P. Jermannaud et al.

    Plio-Pleistocene sequence stratigraphic architecture of the eastern Niger Delta: A record of eustasy and aridification of Africa

    Mar. Pet. Geol.

    (2010)
  • Z.R. Jobe et al.

    Two fundamentally different types of submarine canyons along the continental margin of Equatorial Guinea

    Mar. Pet. Geol.

    (2011)
  • B.A. Jolly et al.

    Growth history of fault-related folds and interaction with seabed channels in the toe-thrust region of the deep-water Niger Delta

    Mar. Pet. Geol.

    (2016)
  • M. Lafosse et al.

    Late Pleistocene-Holocene history of a tectonically active segment of the continental margin (Nekor basin, Western Mediterranean, Morocco)

    Mar. Pet. Geol.

    (2018)
  • A.S. Madof et al.

    Unreciprocated sedimentation along a mud-dominated continental margin, Gulf of Mexico, U.S.A.: Implications for sequence stratigraphy in muddy settings devoid of depositional sequences

    Mar. Pet. Geol.

    (2017)
  • C.K. Morley et al.

    Deep-water fold and thrust belt classification, tectonics, structure and hydrocarbon prospectivity

    Earth Sci. Rev.

    (2011)
  • H. Pälike et al.

    Extended orbitally forced palaeoclimatic records from the equatorial Atlantic Ceara Rise

    Quat. Sci. Rev.

    (2006)
  • M. Picot et al.

    Monsoon control on channel avulsions in the Late Quaternary Congo Fan

    Quat. Sci. Rev.

    (2019)
  • B.E. Prather

    Controls on reservoir distribution, architecture ad stratigraphic trapping in slope settings

    Mar. Petrol.

    (2003)
  • M. Rabineau et al.

    Paleosea levels reconsidered from direct observation of paleo-shoreline position during Glacial Maxima (for the last 500 000 yr)

    Earth Planet. Sci. Lett.

    (2006)
  • M. Rabineau et al.

    Quantifying subsidence and Isostasy using paleobathymetric markers: Example from the Gulf of Lion

    EPSL

    (2014)
  • M.E. Raymo et al.

    The accuracy of mid-Pliocene δ18O based ice volume and sea level reconstructions

    Earth-Sci. Rev.

    (2018)
  • V. Riboulot et al.

    Geometry and chronology of late Quaternary depositional sequences in the Eastern Niger Submarine Delta

    Mar. Geol.

    (2012)
  • D. Rouby et al.

    Gravity driven deformation controlled by the migration of the delta front: The Plio-Pleistocene of the Eastern Niger Delta

    Tectonophysics

    (2011)
  • D.-G. Yoo et al.

    Plio-Quaternary seismic stratigraphy and depositional history of the Ulleung Basin, East Sea: Association with debris-flow activity

    Quat. Int.

    (2017)
  • M. Zecchin

    The architectural variability of small-scale cycles in shelf and ramp clastic systems: the controlling factors

    Earth-Sci. Rev.

    (2007)
  • A.A. Adeogba et al.

    Transient fan architecture and depositional controls from near-surface 3D seismic data, Niger Delta continental slope

    AAPG Bull.

    (2005)
  • Armitage, S.J., Bristow, C.S., Drake, N.A, 2015, West African monsoon dynamics inferred from abrupt fluctuations of...
  • J.L.R Allen

    Late Quaternary Niger Delta and adjacent areas: sedimentary environments and lithofacies

    AAPG Bulletin

    (1965)
  • J. Backman et al.

    Biozonation and biochronology of Miocene through Pleistocene calcareous nannofossils from low and middle latitudes

    Newsl. Stratigr.

    (2012)
  • O. Bakare et al.

    Effect of Growing Structures on Stratigraphic Evolution, Channel Architecture, and Submarine Fan Distribution, Niger Delta, West Africa

    (2007)
  • P. Bellingham et al.

    The deep-water Niger delta: An underexplored world class petroleum province

    Petrol. Geosci. Mag.

    (2014)
  • F.D. Bilotti et al.

    Detachment fold, Niger Delta

  • D.W. Burbank

    Causes of recent Himalayan uplift deduced from deposited patterns in the Ganges basin

    Nature

    (1992)
  • P.M. Burgees et al.

    Stratigraphic forward modeling of basin-margin clinoform systems: Implications for controls on topset and shelf width and timing of formation of shelf-edge deltas

    SEPM

    (2008)
  • O. Catuneanu

    Principles of sequence stratigraphy

    (2006)
  • O. Catuneanu

    Seqquence stratigraphy of deepwater systems

    Mar. Pet. Geol.

    (2020)
  • O. Catuneanu et al.

    Sequence stratigraphy: Methodology and nomenclature

    Newslett. Stratigr.

    (2011)
  • M. Chapin et al.

    Integrated seismic and subsurface characterization of Bonga Field, offshore Nigeria

    Lead. Edge

    (2002)
  • S. Chopra et al.

    Seismic attributes for prospect identification and reservoir characterization. Tulsa, Oklahoma

    (2007)
  • I.R. Clark et al.

    Interactions between coeval sedimentations and deformation from the Niger Delta deep-water fold belt

    SEPM

    (2012)
  • C.D. Connors et al.

    Compressive anticlines of the mid-outer slope, central Niger Delta (abs.)

    AAPG Bull.

    (1998)
  • Cited by (0)

    View full text