Structural architecture of the ocean–continent boundary at an oblique transform margin through deep-imaging seismic interpretation and gravity modelling: Equatorial Guinea, West Africa

Wilson, Paul; Turner, Jonathan P.; Westbrook, G. K.

doi:10.1016/s0040-1951(03)00326-3

Cited by 60 publications

(55 citation statements)

References 49 publications

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“…[34] The crust at the continent-ocean transitional domain along the conjugate margins of the central segment has previously been defined as "proto-oceanic crust" (POC) [Mohriak and Rosendahl, 2003;Wilson et al, 2003;Rosendahl et al, 2005], "igneous crust" [Mohriak et al, 2008], exhumed lower/middle crust [Aslanian et al, 2009] and exhumed and serpentinized subcontinental mantle . Our analysis of seismic reflection data integrated with gravity modeling, however, casts doubt on the previous interpretations as we believe that the transitional domain observed along the conjugate margins of the central segment is not necessarily oceanic or lower crust or serpentinized mantle in nature (Figures 3a-3c and 6).…”

Section: Continental Breakupmentioning

confidence: 99%

“…In this margin setting, local outcrop of serpentinized peridotite ridges across the remaining thin veil of crust may not be unusual [Sibuet, 1987]. If this is the case, serpentinized upper lithospheric mantle has become unroofed and emplaced at the basement surface [e.g., Whitmarsh et al, 2001;Wilson et al, 2003;Lavier and Manatschal, 2006;Reston and Pérez-Gussinyé, 2007;Reston, 2009a]. Furthermore, as serpentinized mantle may have a wide range of density values and due to the nonunique interpretation of gravity anomalies, it is difficult or even impossible to exclude such possibility.…”

Section: Continental Breakupmentioning

confidence: 99%

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Crustal breakup and continent-ocean transition at South Atlantic conjugate margins

Blaich¹,

Faleide²,

Tsikalas³

2011

J. Geophys. Res.

151

174

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[1] Seismic reflection and refraction profiles, and potential field data, complemented by crustal-scale gravity modeling and plate reconstructions are used to study the evolution of the central and south segments of the South Atlantic conjugate margins. The central segment is characterized by a hyperextended continent-ocean transitional domain that shows evidence of rotated fault blocks and a detachment surface active during rifting. A polyphase rifting evolution mode, associated with a complex time-dependent thermal structure of the lithosphere, is substantiated for the central segment that is not a "magma-poor" end-member. Increase of volcanic activity during the late stages of rifting may have "interrupted" the extensional system implying a failed exhumation phase that was replaced instead by continental breakup and emplacement of fully igneous crust. The continent-ocean transitional domain along the "magma-dominated" south segment is characterized by a large volume of flood basalts and high-velocity/high-density lower crust. The northern province of the south segment is characterized by symmetrical seaward-dipping reflections and symmetrical continent-ocean transitional domain. The influence of the Tristan da Cunha plume on this province is very likely. The central province of the south segment is characterized by along-strike tectonomagmatic asymmetry, which can be caused by the initial continental stretching and accompanying magmatism rather than by the subsequent seafloor spreading. The Tristan da Cunha plume on the central province may have influenced the volume of magmatism but did not necessarily alter the process of rifted margin formation, implying that the central province of the south segment may have much in common with "magma-poor" margins.

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Section: Continental Breakupmentioning

confidence: 99%

Section: Continental Breakupmentioning

confidence: 99%

Crustal breakup and continent-ocean transition at South Atlantic conjugate margins

Blaich¹,

Faleide²,

Tsikalas³

2011

J. Geophys. Res.

151

174

View full text Add to dashboard Cite

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“…These areas with accentuated riftzone-width along the Brazilian margin are conjugate to areas with reduced rift-zone-width along the West African Margin (Karner & Driscoll, 1999). The COT/COB (white line) of the Brazilian side is from Karner & Driscoll (1999) and of the African side from Wilson et al (2003). Fracture zones are interpreted based on ; Gomes et al (1997) and Davison (1999).…”

Section: Geological Frameworkmentioning

confidence: 99%

“…Note that the discussion presented here is just a first attempt to understand the structural evolution of the other margin segments since there was limited amount of studied data on these regions. Karner & Driscoll (1999) and on the African side from Wilson et al (2003). Bottom: Plate reconstruction showing the main fracture zones and the position of the conjugate margins during breakup (modified from Davison, 1999).…”

Section: Oblique Transform Marginmentioning

confidence: 99%

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Northeastern Brazilian margin: Regional tectonic evolution based on integrated analysis of seismic reflection and potential field data and modelling

2008

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Oceanic residual depth measurements, the plate cooling model, and global dynamic topography

Hoggard¹,

et al. 2017

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Convective circulation of the mantle causes deflections of the Earth's surface that vary as a function of space and time. Accurate measurements of this dynamic topography are complicated by the need to isolate and remove other sources of elevation, arising from flexure and lithospheric isostasy. The complex architecture of continental lithosphere means that measurement of present‐day dynamic topography is more straightforward in the oceanic realm. Here we present an updated methodology for calculating oceanic residual bathymetry, which is a proxy for dynamic topography. Corrections are applied that account for the effects of sedimentary loading and compaction, for anomalous crustal thickness variations, for subsidence of oceanic lithosphere as a function of age and for non‐hydrostatic geoid height variations. Errors are formally propagated to estimate measurement uncertainties. We apply this methodology to a global database of 1936 seismic surveys located on oceanic crust and generate 2297 spot measurements of residual topography, including 1161 with crustal corrections. The resultant anomalies have amplitudes of ±1 km and wavelengths of ∼1000 km. Spectral analysis of our database using cross‐validation demonstrates that spherical harmonics up to and including degree 30 (i.e., wavelengths down to 1300 km) are required to accurately represent these observations. Truncation of the expansion at a lower maximum degree erroneously increases the amplitude of inferred long‐wavelength dynamic topography. There is a strong correlation between our observations and free‐air gravity anomalies, magmatism, ridge seismicity, vertical motions of adjacent rifted margins, and global tomographic models. We infer that shorter wavelength components of the observed pattern of dynamic topography may be attributable to the presence of thermal anomalies within the shallow asthenospheric mantle.

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Structural architecture of the ocean–continent boundary at an oblique transform margin through deep-imaging seismic interpretation and gravity modelling: Equatorial Guinea, West Africa

Cited by 60 publications

References 49 publications

Crustal breakup and continent-ocean transition at South Atlantic conjugate margins

Crustal breakup and continent-ocean transition at South Atlantic conjugate margins

Northeastern Brazilian margin: Regional tectonic evolution based on integrated analysis of seismic reflection and potential field data and modelling

Oceanic residual depth measurements, the plate cooling model, and global dynamic topography

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