Tight Reassembly of Gondwana Exposes Phanerozoic Shears in Africa as Global Tectonic Players

Reeves, C.V.; Wit, Maarten J. de; Sahu, Bijaya Kumar

doi:10.1016/s1342-937x(05)70302-6

Cited by 52 publications

(36 citation statements)

References 27 publications

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“…This is consistent with the hypothesis of Burke (1996) that such a system was captured by a small west flowing river to produce the Congo Basin and the Congo delta on the Atlantic coast seen today. Reeves et al (2004) suggest that around the time of separation of Africa from South America (110-130 Ma), the new Atlantic coastline was similar to the East African Rift system. Thus shoulder uplifts on either side of the protoAtlantic Rift would exist, like the branches on either side of the East African Rift valley.…”

Section: Proposed Model For Drainage Evolution Since the Cretaceousmentioning

confidence: 92%

“…To accommodate this, Burke and Dewey (1974) first suggested that in the Cretaceous Africa behaved like two plates separated by rifting in West Africa. A more satisfactory fit can be obtained using this concept (Reeves, 2001;Reeves et al, 2004;Reeves and Davison, 2005). A model of this Cretaceous West and Central African Rift system was presented by Fairhead (1988), and is superimposed here on the drainage of the region (Fig.…”

Section: Northern and North-western Flank Of The Congo Basin: West Afmentioning

confidence: 99%

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A proposed drainage evolution model for Central Africa—Did the Congo flow east?

Stankiewicz

Wit

2006

Journal of African Earth Sciences

116

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Section: Proposed Model For Drainage Evolution Since the Cretaceousmentioning

confidence: 92%

Section: Northern and North-western Flank Of The Congo Basin: West Afmentioning

confidence: 99%

A proposed drainage evolution model for Central Africa—Did the Congo flow east?

Stankiewicz

Wit

2006

Journal of African Earth Sciences

116

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“…The history of this continental segmentation and subsequent movement is complex, but has been convincingly reconstructed using rigid plate models based on oceanic fracture zones and magnetic anomalies, and the rotation poles derived from them, and then refined further by alignment of piercing points at conjugate margins of the dispersed Gondwana fragments, using continental aeromagnetic and geological markers [Reeves and de Wit, 2000;Sahu, 2001;Reeves et al, 2002Reeves et al, , 2004Jokat et al, 2005]. First-order features of the evolution of the Indo-Atlantic Oceans appear now to be incontrovertible ( fig.…”

Section: The Origins Of Africa Madagascar India and The Indo-atlantmentioning

confidence: 99%

Reconciling the Origins of Africa, India and Madagascar with Vertebrate Dispersal Scenarios

Masters¹,

Wit²,

Asher³

2006

IJFP

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Africa, India and Madagascar were once part of the supercontinent of Gondwana. This land mass began to fragment approx. 170 million years ago, and by 83 million years, all of the major components we recognize today were separated by tracts of water. Madagascar’s fossil record and estimates of the timing of the extant vertebrate radiations in Madagascar are not easily reconciled with this history of fragmentation. Fossil faunas that lived prior to approx. 65 million years had a cosmopolitan flavour, but this was lost after the Cretaceous-Tertiary boundary. Phylogenetic reconstructions of most extant Malagasy vertebrate radiations indicate divergence times that postdate the End-Cretaceous (lemurs, tenrecs, cichlid fish) and even the Early Miocene (chameleons, carnivores, rodents). Most biogeographic explanations of these groups rely, therefore, on Simpson’s model of sweepstakes dispersal (see also cover figure), but there are significant problems in applying the model to migrations from Africa to Madagascar, although its application is not so intractable between India and Madagascar. Alternative migration routes for consideration lie: (1) along the suite of fracture zones between Antarctica and Africa/Madagascar (known as the Antarctic-Africa Corridor), which may have been exposed episodically above sea level; (2) along a series of submerged basaltic ridges/plateaus with known or suspected continental crust between Antarctica and Africa/Madagascar/India flanking the Antarctic-Africa Corridor (e.g. the Madagascar Ridge, Mozambique Ridge, Conrad Plateau, Gunnerus Ridge); (3) between Africa and Madagascar along the Davie Ridge (parts of which are known to have been exposed episodically above sea level); (4) along the Deccan hotspot corridor between India and greater Africa.

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“…1), sandwiched between India and eastern Africa (e.g. Stern 1994;Lawver et al 1999;Veevers 2001;Reeves et al 2002Reeves et al , 2004Collins and Windley 2002;MacDonald et al 2003;Collins and Pisarevsky 2005;Collins 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Nicollet 1990;Windley et al 1994;Martelat et al 1997;Martelat et al 2000;de Wit et al 2001) and an exposed length of about 350 km (Martelat et al 2000). Because of its oblique orientation with respect Reeves 2008, unpubl., model CR09MZRJ.rot, which is an updated version of model reev519c published in Reeves et al 2004). Purple geometrically rigid Precambrian continental crust, white areas of continental crust that have been extended and lost from outcrop by rifting, dark grey zones with steep foliations that have been interpreted as ductile shear zones.…”

Section: Introductionmentioning

confidence: 99%

A new perspective on the significance of the Ranotsara shear zone in Madagascar

Schreurs

Giese

Berger³

et al. 2009

Int J Earth Sci (Geol Rundsch)

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The Ranotsara shear zone in Madagascar has been considered in previous studies to be a [350-km-long, intracrustal strike-slip shear zone of Precambrian/Cambrian age. Because of its oblique strike to the east and west coast of Madagascar, the Ranotsara shear zone has been correlated with shear zones in southern India and eastern Africa in Gondwana reconstructions. Our assessment using remote sensing data and field-based investigations, however, reveals that what previously has been interpreted as the Ranotsara shear zone is in fact a composite structure with a ductile deflection zone confined to its central segment and prominent NW-SE trending brittle faulting along most of its length. We therefore prefer the more neutral term ''Ranotsara Zone''. Lithologies, tectonic foliations, and axial trace trajectories of major folds can be followed from south to north across most of the Ranotsara Zone and show only a marked deflection along its central segment. The ductile deflection zone is interpreted as a result of E-W indentation of the Antananarivo Block into the less rigid, predominantly metasedimentary rocks of the Southwestern Madagascar Block during a late phase of the Neoproterozoic/Cambrian East African Orogeny (c. 550-520 Ma). The Ranotsara Zone shows significant NW-SE striking brittle faulting that reactivates part of the NW-SE striking ductile structures in the flexure zone, but also extends along strike toward the NW and toward the SE. Brittle reactivation of ductile structures along the central segment of the Ranotsara Zone, confirmed by apatite-fission track results, may have led to the formation of a shallow Neogene basin underlying the Ranotsara plain. The present-day drainage pattern suggests on-going normal fault activity along the central segment. The Ranotsara Zone is not a megascale intracrustal strike-slip shear zone that crosscuts the entire basement of southern Madagascar. It can therefore not be used as a piercing point in Gondwana reconstructions.

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Tight Reassembly of Gondwana Exposes Phanerozoic Shears in Africa as Global Tectonic Players

Cited by 52 publications

References 27 publications

A proposed drainage evolution model for Central Africa—Did the Congo flow east?

A proposed drainage evolution model for Central Africa—Did the Congo flow east?

Reconciling the Origins of Africa, India and Madagascar with Vertebrate Dispersal Scenarios

A new perspective on the significance of the Ranotsara shear zone in Madagascar

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