West African and Brazilian Conjugate Margins: Crustal Types, Architecture, and Plate Configurations

Rosendahl, Bruce R.; Mohriak, Webster Ueipass; Odegard, Mark E.; Turner, Jonathan P.; Dickson, William

doi:10.5724/gcs.05.25.0261

Cited by 22 publications

(24 citation statements)

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“…In particular, along the northeastern Brazil-Gabon conjugate margin, the data set was provided courtesy to Statoil and comprises seismic reflection profiles acquired by TGS-NOPEC (Camamu/Almada basins) and ION-GXT (South Gabon Basin). Published seismic reflection [Rosendahl et al, 1991;Meyers et al, 1996aMeyers et al, , 1996bRosendahl and Groschel-Becker, 1999;Rosendahl et al, 2005] and wideangle refraction profiles [Wannesson et al, 1991] along the Gabon margin have also been analyzed, revised and incorporated into our interpretations. Farther south, along the conjugate southeastern Brazil-Angola margin, industrial reflection seismic profiles acquired by Fugro Multi Client Services (Espírito Santo Basin) were at our disposal.…”

Section: Discussionmentioning

confidence: 99%

“…Along the conjugate margin off Gabon, a prominent gravity anomaly low that flanks the "edge effect" gravity anomaly high abruptly terminates to the north at the N'Komi Transfer Zone (Figure 2c). These observations suggest a segmented along-margin character which may be attributed to a distinct and probably inherited segmentation of this part of the South Atlantic margins, where Archean-Paleoproterozoic structures probably exerted a strong control on the patterns of rifting and breakup and where major changes in lithospheric strength may have occurred [e.g., Watts and Stewart, 1998;Rosendahl et al, 2005]. Farther south, the continuous, prominent and elongated gravity anomaly high along both conjugate margins is interrupted by a broad gravity high characterized by the Abrolhos volcanic complex and by the Congo Fan.…”

Section: Margin Settingmentioning

confidence: 99%

“…Two such end-member margins have been subjected to intense debate, the "magma-dominated" and the "magmapoor" margins. In this context, possibly anomalous crust located within the continent-ocean transitional domain has been recognized along several margin segments in South Atlantic and described variously as 'proto-oceanic crust,' 'attenuated continental crust', and 'transitional crust' [e.g., Meyers et al, 1996aMeyers et al, , 1996bRosendahl and Groschel-Becker, 1999;Wilson et al, 2003;Moulin et al, 2005;Rosendahl et al, 2005]. However, in most of the passive margins worldwide the nature and the precise evolution of the crust at the transitional domain from early rifting to breakup of the continental lithosphere is still unclear and several alternative models have been proposed [Whitmarsh et al, 1996;Wilson et al, 2003;Rosendahl et al, 2005;Kusznir and Karner, 2007;Afilhado et al, 2008;Reston, 2009a].…”

Section: Continental Breakupmentioning

confidence: 99%

“…[2] The extensional margin evolution from rift through breakup rupture of the continental lithosphere to progressive oceanic crust formation remains controversial [e.g., Rosendahl et al, 2005;Sawyer et al, 2007;Reston and Pérez-Gussinyé, 2007;Rosenbaum et al, 2008]. Complicating the issue, the deep crustal structures along several margins are partially or totally masked by evaporite deposits and/or by magmatic materials which deteriorate the seismic reflection resolution at depth.…”

Section: Introductionmentioning

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: Discussionmentioning

confidence: 99%

Section: Margin Settingmentioning

confidence: 99%

Section: Continental Breakupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Blaich¹,

Faleide²,

Tsikalas³

2011

J. Geophys. Res.

151

174

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“…The Late Tertiary evaporite deposits occur as gypsum beds onshore and as salt diapirs offshore. There is no clear evidence for an active spreading center in the northern Red Sea, and the Gulf of Suez might have been aborted as the transform fault between the Sinai Peninsula and Arabia formed the Gulf of Aqaba / Dead Sea rift systems, in a process similar to the abandonment of the onshore Recôncavo-Tucano-Jatobá rits in Brazil (Szatmari & Milani 1999;Rosendahl et al 2005). In this case, transform faults developed as the oceanic crust was formed between the Bahia -Sergipe and northern Gabon continental margins Further south, in the Central Red Sea (24 o N to 19 o N) the seismic, gravity and magnetic surveys indicate that oceanic crust occurs on both flanks of the axial trough, where a presentday spreading center is indicated by seismic data.…”

Section: " "mentioning

confidence: 99%

Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Mohriak

Leroy

2012

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To cite this version:Webster Ueipass Mohriak, Sylvie Leroy. Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea-Gulf of Aden conjugate margins. Special Publication -Geological Society of London, 2012, 369, pp.1-40. <10.1144/SP369.17>. !" " " ARCHITECTURE OF RIFTED CONTINENTAL MARGINS AND BREAKUP EVOLUTION: INSIGHTS FROM THE SOUTH ATLANTIC, NORTH ATLANTIC AND RED SEA -GULF OF ADEN CONJUGATE MARGINS

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Conjugate rifted margins width and asymmetry: The interplay between lithospheric strength and thermomechanical processes

2015

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Numerical experiments have been used to relate the range in the distribution and the style of deformation observed in rifted margins to localizing/delocalizing thermomechanical processes. The experiments give rise to four end‐members of margins for varying initial lithospheric strength and extension rates. The first two end‐members are narrow and asymmetric and narrow and near‐symmetric, conjugate margins. The third end‐member is asymmetric conjugate margins, wherein one side is <100 km wide and the other is >100–300 km wide. Lastly, we explore wide rift systems that may form very asymmetric conjugate margins with one narrow margin and a very wide conjugate, 200 km to > 350 km across. With initial and boundary conditions close to that inferred from the North and South Atlantic margins, we find that not all margins experience a polyphase rifting history of stretching‐thinning‐exhumation. Instead, the stretching mode can be very short or protracted, and the thinning or the exhumation modes can be incomplete or absent. The deformation localization of the thinning mode is in places associated with the formation of a keystone block or “block H.” A new mechanism for the formation of the unstable crustal root under block H is described, wherein the bounding border faults lead to differential thinning of the crust and mantle lithosphere. Nonuniform extension also occurs in both types of wide rift systems and is related to the sequential deformation migration outward of an initial graben, associated with effective lithospheric strengthening that occurs during crustal thinning and bending.

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West African and Brazilian Conjugate Margins: Crustal Types, Architecture, and Plate Configurations

Cited by 22 publications

References 0 publications

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

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

Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Conjugate rifted margins width and asymmetry: The interplay between lithospheric strength and thermomechanical processes

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