New seismic data in the Mozambique Channel |
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Authors: | J M Lort W Q Limond J Segoufin Ph Patriat J R Delteil B Damotte |
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Institution: | (1) Observatoire Géophysique de l'Institut de Physique du Globe, 4 Av. de Neptune, 94100 St. Maur-des-Fossés, France;(2) Present address: British Petroleum, Moor Lane, EC2Y 9BU London, UK;(3) Entreprise de Recherches et d'Activités Petrolières ELF, 7 Rue Nelaton, 75015 Paris, France;(4) Institut Français de Pétrole, 1-4 Av. de Bois Préau, 92 Rueil Malmaison, France |
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Abstract: | This paper presents seismic reflection and refraction data from the Mozambique Channel, collected between 1971 and 1973. A deep sedimentary basin (up to 5 km of sediments) opens southwards to the Mozambique Basin, and is bounded to the east by the Davie Ridge and beyond by the marginal plateau of Malagasy. A continuous reflector (C), possibly of Cretaceous age, is identified between layers having seismic interval velocities of 2.4–2.8 km/s and 3.1–3.4 km/s. The deepest sediments have velocities of 4.5–4.9 km/s and overlie a layer with velocity 5.5 km/s, which may be volcanic in the north-east of the Channel.The crust occupying most of the Channel is probably pre-Cretaceous in age, and may be largely continental in nature. This is supported by subdued magnetic anomalies and the possibility of a continuous Karroo sedimentary section across the northern Channel. The oceanic crust of the Mozambique Basin may extend as far north as 24°S, into the western Channel only. The problem of the origin of the Mozambique Channel remains unresolved, although a long sedimentary history indicates that Malagasy may have separated from Mainland Africa prior to Karroo times. The Davie Ridge may possibly represent a relict strike-slip fault, which permitted movement along a north-south line. |
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