Seismic sequence stratigraphy and tectonics offshore Namibia

Light, M.P.R.; Maslanyj, M. P.; Greenwood, Richard; Banks, N. L.

doi:10.1144/gsl.sp.1993.071.01.08

Cited by 58 publications

(86 citation statements)

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“…A significant rift onset unconformity has been identified in a number of previous seismic reflection studies (e.g. Gerrard and Smith 1982;Light et al 1993) and has been attributed to the initiation of the main South Atlantic rift phase in the Late Jurassic.…”

Section: Regional Settingmentioning

confidence: 70%

“…As a consequence of limited well data in the offshore, and the absence of significant Palaeozoic onshore outcrops, the stratigraphy of the post Pan-African basement is uncertain on the Namibian margin. It is generally considered that the basement is overlain by a CarboniferousPermian stratigraphy associated with the Karoo foreland basin (Maslanyj et al 1992;Light et al 1993). This is subsequently overlain by deposits associated with the early stages of continental rifting, although again the timing of this is poorly constrained.…”

Section: Regional Settingmentioning

confidence: 99%

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Interaction of crustal heterogeneity and lithospheric processes in determining passive margin architecture on the southern Namibian margin

Mohammed

Paton

Collier

et al. 2016

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Abstract:The influence of pre-rift crustal heterogeneity and structure upon the evolution of a continental rift and its subsequent passive margin is explored. The absence of thick Aptian salts in the Namibian South Atlantic allows imaging of sufficient resolution to distinguish different pre-rift basement seismic facies. Aspects of pre-rift basement geometry have been characterized which are then compared with the geometries of Cretaceous rift basin structure, and of subsequent post-rift margin architectural elements. Half-graben depocentres migrate westward within the continental syn-rift phase, at the same time as basin bounding faults become established as hard-linked arrays with lengths of approximately 100 km. The rift-drift transition phase, marked by Seaward Dipping Reflectors, gives way to the early post-rift progradation of clastics off the Namibian coast. In the Late Cretaceous, these shelf clastics are much thicker in the south, reflecting the dominance of the newly formed Orange River catchment as the main sediment entry point on the South African/Namibian margin. Tertiary clastics largely bypass the pre-existing shelf area, revealing a marked basinwards shift in sedimentation. Post-rift megasequence thicknesses do not vary simply according to the location of syn-rift half-grabens and thinned continental crust. Rather, the Namibian margin exemplifies margins influenced by a complex interplay of crustal thinning, pre-rift basement heterogeneity, volcanic bodies and transient dynamic uplift events on the evolution of lithospheric strain and depositional architectures.

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Section: Regional Settingmentioning

confidence: 70%

Section: Regional Settingmentioning

confidence: 99%

Interaction of crustal heterogeneity and lithospheric processes in determining passive margin architecture on the southern Namibian margin

Mohammed

Paton

Collier

et al. 2016

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“…6) is the other determinant parameter for triggering gravitational tectonics, as shown by the northwards decreases of amplitude and extent of gravitational tectonics, away from the Orange depocentre. Indeed, the thin Tertiary sequence off Namibia, is not affected by gravitational deformation (Light et al, 1993). During deposition of the whole drift sequence, shallow slumping affected the upper slope of southernmost SW Africa margin, and during Neogene slumping also affected the slope off the Orange River mouth (Dingle and Robson, 1992).…”

Section: Gravitational Tectonicsmentioning

confidence: 99%

South Atlantic continental margins of Africa: A comparison of the tectonic vs climate interplay on the evolution of equatorial west Africa and SW Africa margins

Séranne¹,

Anka²

2005

Journal of African Earth Sciences

135

106

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Africa displays a variety of continental margin structures, tectonic styles and sedimentary records. The comparative review of two representative segments: the equatorial western Africa and the SW Africa margins, helps in analysing the main controlling factors on the development of these margins. Early Cretaceous active rifting south of the Walvis Ridge resulted in the formation of the SW Africa volcanic margin that displays thick and wide intermediate igneous crust, adjacent to a thick unstretched continental crust. The non-volcanic mode of rifting north of the Walvis ridge, led to the formation of the equatorial western Africa margin, characterised by a wide zone of crustal stretching and thinning, and thick, extensive, synrift basins. Contrasting lithologies of the early post-rift (salt vs shale) determined the style of gravitational deformation, whilst periods of activity of the decollements were controlled by sedimentation rates. Regressive erosion across the prominent shoulder uplift of SW Africa accounts for high clastic sedimentation rate during Late Cretaceous to Eocene, while dominant carbonate production on equatorial western Africa shelf suggests very little erosion of a low hinterland. The early Oligocene long-term climate change had contrasted response in both margins. Emplacement of the voluminous terrigenous Congo deep-sea fan reflects increased erosion in equatorial Africa, under the influence of wet climate, whereas establishment of an arid climate over SW Africa induced a drastic decrease of denudation rate, and thus reduced sedimentation on the margin. Neogene emplacement of the African superswell beneath southern Africa was responsible for renewed onshore uplift on both margins, but it accelerated erosion only in the Congo catchment, due to wetter climatic conditions. Neogene high sedimentation rate reactivated gravitational tectonics that had remained quiescent since late Cretaceous.

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“…(Light et al, 1993, 84 Muntingh & Brown, 1993, Paton et al, 2007, 2008, Hirsch et al, 2010. basin is extensive, though limited to the shelf margin, and has been used by previous studies (e.g.…”

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confidence: 99%

Influence of mechanical stratigraphy on multi-layer gravity collapse structures: insights from the Orange Basin, South Africa

Dalton

Paton

Needham³

2016

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6Gravity collapse structures are common features on passive margins and typically have a tripartite 7 configuration including an up-dip extensional domain, transitional domain and a down-dip 8 compressional domain with a common detachment underlying the system. A number of recent studies 9 have classified these systems, yet few document the wide variation in geometry. 10This study documents the gravity collapse structures of the Namibian and South African Orange Basin 11 as these represent some of the best imaged examples globally of this important process. Firstly, we 12 demonstrate the geometry and kinematic evolution of these systems, focussing on examples of the 13 tripartite configuration from a typical collapse. We then highlight the significant variability in the systems 14 structures describing features such as; portions of the system with multiple detachments; systems with 15 stacked synchronous detachments; the temporal evolution of faults within the system. Integrating our 16 observations from a number of sections we present a model explaining the spatial and temporal 17 evolution of the system. This enables us to discuss likely causes of collapse structures but also, by 40In this study we focus on shale detachment systems that, regardless of the driving mechanism 54In this study we look in detail at the three domains along a typical section from the Orange Basin 55 system, before comparing them to other portions of the same collapse structure to observe variations 56 along strike. From these observations we construct a model to explain the temporal evolution of this 57 important margin process. Finally we consider how the margin stratigraphy plays a critical role in the 58 nature of the deformation and propose that this has a significant, and as to now unrecognised control 59 on this process that occurs on many passive margins. 61 Regional Setting 63The Orange Basin is the southernmost basin on the West African passive margin; forming during the 64 break-up of Gondwana and subsequent spreading of the South Atlantic Ocean (Muntingh & Brown, 65 1993, Brown et al.,1995, Paton et al., 2008, Koopman et al., 2014. (Light et al., 1993, 84 Muntingh & Brown, 1993, Paton et al., 2007, 2008, Hirsch et al., 2010. basin is extensive, though limited to the shelf margin, and has been used by previous studies (e.g.

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Seismic sequence stratigraphy and tectonics offshore Namibia

Cited by 58 publications

References 10 publications

Interaction of crustal heterogeneity and lithospheric processes in determining passive margin architecture on the southern Namibian margin

Interaction of crustal heterogeneity and lithospheric processes in determining passive margin architecture on the southern Namibian margin

South Atlantic continental margins of Africa: A comparison of the tectonic vs climate interplay on the evolution of equatorial west Africa and SW Africa margins

Influence of mechanical stratigraphy on multi-layer gravity collapse structures: insights from the Orange Basin, South Africa

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