Magmatism and rifting in Western and Central Africa, from Late Jurassic to Recent times

Wilson, Marjorie; Guiraud, René

doi:10.1016/b978-0-444-89912-5.50038-7

Cited by 51 publications

(59 citation statements)

References 80 publications

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“…Outside cratonic areas, the lithosphere is thinner and some lines of weakness persist from the past tectonics of Africa. The Central African shear zone (CASZ in Figure 3) from Cameroon to Sudan [Wilson and Guiraud, 1992] is a Mesozoic rift reactivated about 30 Ma ago. The thick root of African cratons and the thinner lithosphere between them might give rise to convective instabilities with a mechanism similar to edge-driven con- vection [Guillou and Jaupart, 1995;King and Ritsema, 2000].…”

Section: Discussion: Geodynamical Interpretationmentioning

confidence: 99%

“…A first phase of active volcanism related to the breakup of Gondwana continent during Mesozoic (245 -66 Ma) was followed by a quiet interval of time during the early Cenozoic (66 -30 Ma) [Burke, 1996]. Since Oligocene (33 -23 Ma), renewed volcanic activity [Wilson and Guiraud, 1992] was particularly important in the Horn of Africa where $1 Â 10 6 km 3 continental flood basalts (CFB) in Ethiopia erupted 30 Ma ago in a time interval of 1 Ma or less [Hofmann et al, 1997;Ayalew, 2002]. The Afar volcanic province, still magmatically active though with large temporal variations, is thought to represent the surface expression of a deep mantle plume [Morgan, 1971], originating either in the transition zone [Debayle et al, 2001] or even deeper in the lower mantle [Nyblade and Robinson, 1994;Montelli et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

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Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Montagner¹,

Marty²,

Stutzmann³

et al. 2007

Geophysical Research Letters

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International audienceThe relationship between intraplate volcanism and continental tectonics has been investigated for North and East Africa using a high resolution three-dimensional anisotropic tomographic model derived from seismic data of a French experiment “Horn of Africa” and existing broadband data. The joint inversion for seismic velocity and anisotropy of the upper 400 km of the mantle, and geochemical data reveals a complex interaction between mantle upwellings, and lithosphere. Two kinds of mantle upwellings can be distinguished: The first one, the Afar “plume” originates from deeper than 400 km and is characterized by enrichment in primordial 3He and 3He/4He ratios higher than those along mid-ocean ridges (MOR). The second one, associated with other Cenozoic volcanic provinces (Darfur, Tibesti, Hoggar, Cameroon), with 3He/4He ratios similar to, or lower than MOR, is a consequence of shallower upwelling. The presumed asthenospheric convective instabilities are oriented in an east-west direction, resulting from interaction between south-north asthenospheric mantle flow, main plume head and topography on the base of lithosphere

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Section: Discussion: Geodynamical Interpretationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Montagner¹,

Marty²,

Stutzmann³

et al. 2007

Geophysical Research Letters

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“…The first phase (Early Cretaceous: 141-106 Ma; Baudin, 1991) is related to the main extensional tectonic regime which affected the trough. During the Tertiary, basaltic magmas were emplaced throughout the entire trough with the greatest concentration in the NE (Wilson & Guiraud, 1992). This Post-Cretaceous extension and volcanism in the Upper Benue corresponds to a period of general stress release after the Santonian or Cretaceous compressional events (Benkhelil, 1989).…”

Section: Swell-and-basin Structures and Magmatic Provincesmentioning

confidence: 99%

“…This is related to strike-slip movements along the Central African Shear Zone (Bosworth, 1992). Magmatic activity in the BT was particularly important during the Cretaceous-Early Tertiary and took place in many phases, contemporaneous with the opening and infilling of the trough (Wilson & Guiraud, 1992). The first phase (Early Cretaceous: 141-106 Ma; Baudin, 1991) is related to the main extensional tectonic regime which affected the trough.…”

Section: Swell-and-basin Structures and Magmatic Provincesmentioning

confidence: 99%

“…Some workers (e.g. Wilson & Guiraud, 1992;Lee et al, 1994;Ebinger & Sleep, 1998) link it to the role of mantle plumes. However, most African hotspots have been active since the Cretaceous; thus, to explain the extensive Triassic-Early Jurassic magmatism along the West African and North American margins, Wilson (1997) suggested the location of a pre-Pangea continental break-up 'super plume' axis beneath West Africa.…”

Section: Continental Breaking and Possible Links With Magmatic Chainsmentioning

confidence: 99%

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Plates Amalgamation and Plate Destruction, the Western Gondwana History

Ngako¹,

Njonfang²

2011

Tectonics

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Tectonics 4This study involves modern structural analysis and concepts (phase chronology, strain analysis, deformation and kinematics), petrology (metamorphic parageneses and phase equilibrium, relation with deformation, geothermobarometry), geochemistry (major and trace elements) and geochronology. Data from regional literature including geophysical data are also abundantly used for synthesis and re-interpretation. The most important achievements include: 1. A new tectonic model for the Pan-African/Brasiliano belts; this model includes many original aspects and developments with regards to the collisional setting, tectonics, metamorphic and magmatic processes. In particular, a three-plate model is proposed, and the role of the asthenosphere on crustal melting and reactivation during collision is emphasized. 2. Evidence of a tectonic indent in the central Nigeria-Cameroon domain, inferred from the regional strain field; indentation in central-west Africa strongly suggests that the East Saharan Block (ESB) evolved originally as a rigid prong prior to crustal melting, batholiths emplacement and subsequent dismantling of the prong during the late PanAfrican evolution. 3. Clear distinction between Pan-African and Post Pan-African tectonic and magmatic processes which raises the question on the relevance of integrating Phanerozoic lithospheric structures inferred from geophysical data (gravity, seismic tomography, etc.) in the interpretation and reconstruction of the Pan-African tectonic evolution. Future research would be focused on the Central Cameroon Shear Zone (CCSZ) kinematics and the characterization of vestiges of the dismantled SFCC/ESB cratons and hypothetic pre-tectonic boundaries.

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Uplift histories of Africa and Australia from linear inverse modeling of drainage inventories

et al. 2015

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We describe and apply a linear inverse model which calculates spatial and temporal patterns of uplift rate by minimizing the misfit between inventories of observed and predicted longitudinal river profiles. Our approach builds upon a more general, nonlinear, optimization model, which suggests that shapes of river profiles are dominantly controlled by upstream advection of kinematic waves of incision produced by spatial and temporal changes in regional uplift rate. Here we use the method of characteristics to solve a version of this problem. A damped, nonnegative, least squares approach is developed that permits river profiles to be inverted as a function of uplift rate. An important benefit of a linearized treatment is low computational cost. We have tested our algorithm by inverting 957 river profiles from both Africa and Australia. For each continent, the drainage network was constructed from a digital elevation model. The fidelity of river profiles extracted from this network was carefully checked using satellite imagery. River profiles were inverted many times to systematically investigate the trade-off between model misfit and smoothness. Spatial and temporal patterns of both uplift rate and cumulative uplift were calibrated using independent geologic and geophysical observations. Uplift patterns suggest that the topography of Africa and Australia grew in Cenozoic times. Inverse modeling of large inventories of river profiles demonstrates that drainage networks contain coherent signals that record the regional growth of elevation.

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Magmatism and rifting in Western and Central Africa, from Late Jurassic to Recent times

Abstract: Wilson, M. and Guiraud, R., 1992. Magmatism and rifting in Western and Central Africa, from Late Jurassic to Recent

Cited by 51 publications

References 80 publications

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Plates Amalgamation and Plate Destruction, the Western Gondwana History

Uplift histories of Africa and Australia from linear inverse modeling of drainage inventories

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