scholarly journals Weak orogenic lithosphere guides the pattern of plume-triggered supercontinent break-up

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Zhuo Dang ◽  
Nan Zhang ◽  
Zheng-Xiang Li ◽  
Chuan Huang ◽  
Christopher J. Spencer ◽  
...  
Keyword(s):  
South Atlantic ◽  
West African ◽  
Dynamic Evolution ◽  
The West ◽  
Tectonic Plates ◽  
Central Atlantic Magmatic Province ◽  
Geological Features ◽  
Continental Rifts ◽  
Break Up ◽  
Central Atlantic

AbstractThe importance of nonrigid geological features (such as orogens) inside tectonic plates on Earth’s dynamic evolution lacks thorough investigation. In particular, the influence of continent-spanning orogens on (super)continental break-up remains unclear. Here we reconstruct global orogens and model their controlling effects on Pangea break-up. We show that while loci of Pangea break-up are linked to mantle plumes, development of continental rifts is guided by orogens. Rifting at Central Atlantic is driven by the modelled plume responsible for the Central Atlantic Magmatic Province (CAMP) within Pangea-forming orogens. South Atlantic rifting is controlled by necking between Pangea- and Gondwana-forming orogens with the assistance of plume-induced lithospheric weakening. Without CAMP-induced weakening, South Atlantic rifting fails between the West African and Amazonian cratons, but occurs between the West African and Saharan cratons instead. Our modeling on Pangea break-up is able to recreate present-day continental geometry through the combined effect of orogens and plume center-locations.

scholarly journals Kinematics of the South Atlantic rift

Solid Earth ◽  
2013 ◽  
Vol 4 (2) ◽  
pp. 215-253 ◽  
Author(s):  
C. Heine ◽  
J. Zoethout ◽  
R. D. Müller
Keyword(s):  
South America ◽  
Kinematic Model ◽  
Shear Zones ◽  
South Atlantic ◽  
West African ◽  
Passive Margin ◽  
Equatorial Atlantic ◽  
The South ◽  
Break Up ◽  
Extension Direction

Abstract. The South Atlantic rift basin evolved as a branch of a large Jurassic–Cretaceous intraplate rift zone between the African and South American plates during the final break-up of western Gondwana. While the relative motions between South America and Africa for post-break-up times are well resolved, many issues pertaining to the fit reconstruction and particularly the relation between kinematics and lithosphere dynamics during pre-break-up remain unclear in currently published plate models. We have compiled and assimilated data from these intraplated rifts and constructed a revised plate kinematic model for the pre-break-up evolution of the South Atlantic. Based on structural restoration of the conjugate South Atlantic margins and intracontinental rift basins in Africa and South America, we achieve a tight-fit reconstruction which eliminates the need for previously inferred large intracontinental shear zones, in particular in Patagonian South America. By quantitatively accounting for crustal deformation in the Central and West African Rift Zones, we have been able to indirectly construct the kinematic history of the pre-break-up evolution of the conjugate west African–Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic pre-salt sag basin and the São Paulo High. We model an initial E–W-directed extension between South America and Africa (fixed in present-day position) at very low extensional velocities from 140 Ma until late Hauterivian times (≈126 Ma) when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial ≈14 Myr-long stretching episode the pre-salt basin width on the conjugate Brazilian and west African margins is generated. An intermediate stage between ≈126 Ma and base Aptian is characterised by strain localisation, rapid lithospheric weakening in the equatorial Atlantic domain, resulting in both progressively increasing extensional velocities as well as a significant rotation of the extension direction to NE–SW. From base Aptian onwards diachronous lithospheric break-up occurred along the central South Atlantic rift, first in the Sergipe–Alagoas/Rio Muni margin segment in the northernmost South Atlantic. Final break-up between South America and Africa occurred in the conjugate Santos–Benguela margin segment at around 113 Ma and in the equatorial Atlantic domain between the Ghanaian Ridge and the Piauí-Ceará margin at 103 Ma. We conclude that such a multi-velocity, multi-directional rift history exerts primary control on the evolution of these conjugate passive-margin systems and can explain the first-order tectonic structures along the South Atlantic and possibly other passive margins.

U–Pb baddeleyite and zircon ages of 2040Ma, 1650Ma and 885Ma on dolerites in the West African Craton (Anti-Atlas inliers): Possible links to break-up of Precambrian supercontinents

Lithos ◽  
2013 ◽  
Vol 174 ◽  
pp. 71-84 ◽  
Author(s):  
Djiky Kouyaté ◽  
Ulf Söderlund ◽  
Nasrrddine Youbi ◽  
Richard Ernst ◽  
Ahmid Hafid ◽  
...  
Keyword(s):  
West African ◽  
The West ◽  
West African Craton ◽  
Break Up

Along-Strike Variation of Halokinesis and Structural Inheritance Along the West African Salt Basin, South Atlantic

2020 ◽  
Author(s):  
Etienne Legeay ◽  
Jean-Claude Ringenbach ◽  
Jean-Paul Callot
Keyword(s):  
Cross Sections ◽  
Temporal Distribution ◽  
West African ◽  
Passive Margin ◽  
Distal Margin ◽  
Dynamic Topography ◽  
Regional Study ◽  
The West ◽  
Seismic Reflection Data ◽  
Break Up

<p>Along the West African margin from Gabon to southern Angola, the Loeme Aptian salt deposited during the late rift break-up process. Following the Atlantic opening, passive margin subsidence, large deltas and dynamic topography triggered and shape gravity tectonic systems. Evaporite deposition occurred during the break-up process, from the rupture of the continental crust to the spreading, thus providing an early inheritance (in term of thickness and geographic distribution of evaporites) for future salt tectonics, which is largely controlled by the genetic domain compartmentalizing the margin, namely the proximal margin, the neck basin, the distal margin, and the outer high and exhumed mantle. Classically, since the mid-90s the gravity gliding system pattern, with the usual triptych extension-translation-compression, has been over-applied along the West African margin. Recent data from Angola show mini-basins in a context of gravity spreading in addition to pure gliding-spreading roll-overs, rafts and diapirs, as well as mini basins developed during the early phase of evolution, and were later on squeezed by the gliding cell. We present here a regional study to compare major internal and external factors controlling halokinesis structural styles and we propose new maps and cross-sections up to 300 km long from onshore to ultra-deep offshore, to describe the main domains and styles across the Gabon, Lower Congo, Kwanza, Benguela and Namibe sub-basins. This work is based on an extensive 2D and 3D seismic reflection data, wells and internal reports. Margin scale cartographic compilation of both pre- and post-salt tectono-sedimentary trends provide elements to constrain both geometries and kinematics. This study documents the spatial and temporal distribution of both the inherited salt controlled basins (i.e. minibasins, salt ridges, etc.) as well as the superimposed gravitational systems, their characteristics and drivers (e.g. gliding, spreading), and by linking them to the genetic domains of the margin to highlight their various roles.</p>

The West African connection—Evolution of the central Atlantic Ocean and its continental margins

Geology ◽  
1984 ◽  
Vol 12 (10) ◽  
pp. 635
Author(s):  
John Rodgers ◽  
Jean Sougy ◽  
Frances Delany ◽  
René Dame
Keyword(s):  
Atlantic Ocean ◽  
West African ◽  
Continental Margins ◽  
The West ◽  
Central Atlantic

scholarly journals Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Mahaman Sani Tairou ◽  
Pascal Affaton ◽  
Solomon Anum ◽  
Thomas Jules Fleury
Keyword(s):  
West African ◽  
Normal Faulting ◽  
Clockwise Rotation ◽  
The West ◽  
West African Craton ◽  
Benue Trough ◽  
Pan African ◽  
Volta Basin ◽  
Central Atlantic ◽  
Eastern Edge

This faulting tectonics analysis concerns the southernmost segment of the Dahomeyide Orogen and the West-African craton eastern margin in southeast Ghana. The analysis of strike-slip faults in the frontal units of the Dahomeyide Belt indicates that four distinct compressive events (NE-SW, ENE-WSW to E-W, ESE-WNW to SE-NW and SE-NW to SSE-NNW) originated the juxtaposition of the Pan-African Mobile Zone and the West-African craton. These paleostress systems define a clockwise rotation of the compressional axis during the structuring of the Dahomeyide Orogen (650–550 Ma). The SE-NW and SSE-NNW to N-S compressional axes in the cratonic domain and its cover (Volta Basin) suggest that the reactivation of the eastern edge of the West African craton is coeval with the last stages of the Pan-African tectogenesis in southeast Ghana. An extensional episode expressed as late normal faulting is also recorded in this study. This E-W to SE-NW extension, which is particular to the southernmost part of the Dahomeyide Belt, appears to be post-Pan-African. This extension probably contributed to the formation of a major Jurassic rifting zone that originated the Central Atlantic and the Benue Trough.

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