Geophysics and the Crustal Structure of West Africa

Roussel, J.; Lesquer, A.

doi:10.1007/978-3-642-84153-8_2

Cited by 10 publications

(3 citation statements)

References 55 publications

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“…Therefore, the geothermal gradient prevailing during the West African craton times should be commensurate with the recent one for which values between 15 o C km -1 (Gunnell, 2003) and 23 o C km -1 (Roussel & Lesquer, 1991) are reported. Such cooling pattern ( of 15 o C and 23 o C km -1 ) suggests (i) mid-Palaeozoic episode of slow and homogeneous denudation along the southeastern margin of the Leo shield, and (ii) variable denudation of the newly created La Côte d' Ivoire-Ghana transform margin since the early Cretaceous break up of western Gondwanaland.…”

Section: Discussionsupporting

confidence: 56%

“…Given a recent annual surface temperature of 27 o C (Von Gnielinski, 1986), the amount of post-Jurassic cooling varies between 60 o and 85 o . Using a stable geothermal gradient of 15 o -23 o km -1 (Gunnell, 2003;Roussel & Lesquer, 1991), the accumulated denudation of La Côte d'Ivoire-Ghana margin since the beginning of the continental rifting stage is estimated to have been between 2.5 and 5.5 km. Considering a Cenozoic long-term denudation rate of 11-16 m Ma -1 , as postulated for the topographically and climatically comparable kimberlite diatreme system in Sierra Leone (Thomas, 1995), denudation range between 1.5 and 5 km can be envisaged for early Cretaceous rifting.…”

Section: Discussionmentioning

confidence: 99%

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Cretaceous rifting of the Ghana transform margin - Evidence from on shore apatite fission track data and optimum thermal history models

Hayford¹,

Lisker²,

Apaalse³

2010

Ghana Journal of Science

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The rock samples of the granitoid at the marginal ridge of the Ghanaian shelf within La Côte d' Ivoire continental transform margin, have been studied using fission tracks in apatite. The ages of the apatite fission track (AFT), which are mainly metamorphosed igneous rocks, range from 130 to 415 Ma. Apatite fission track measurements demonstrate that the rocks were cooled from temperatures >110 o C to temperatures below 60 o C during the early Cretaceous. Quantitative thermal histories, derived from rock data from southern Ghana, indicate two stages of cooling and two stages of denudation during Devonian-Permian times, and in the Cretaceous. The denudation was the result of faults and landslides produced by increases in bathymetric step between the continental margin and the oceanic crust. The latter cooling stage commencing at 130 Ma represents the 2.5-5.5 km of basement denudation which is related to intra-continental transform faulting between West Africa and Brazil. The AFT data of La Cote d' Ivoire-Ghana marginal ridge reveal similar times of cooling, thus, ruling out provenance-related AFT ages of the meta igneous rocks. Instead, cooling of ODP samples from the offshore marginal ridge is the consequence of coeval hydrothermal circulation within intracontinental fault acting between African and Brazilian basements.

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Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Cretaceous rifting of the Ghana transform margin - Evidence from on shore apatite fission track data and optimum thermal history models

Hayford¹,

Lisker²,

Apaalse³

2010

Ghana Journal of Science

View full text Add to dashboard Cite

show abstract

“…The late fracturing, linked to the Dn + 4 compression, would be generalized to the whole orogen. Therefore, it is probable that the Wilson Cycle (divergence-convergence) evolution, in the case of the Trans-Saharan Belt, was controlled by the same Panafrican palaeotress fields [16,18,31]. However, it is not excluded that the geometry of the eastern border of the WAC could have influenced these palaeostress fields.…”

Section: Synthesis and Discussionmentioning

confidence: 99%