Seismic reflection profiling and basement topography in the Somali Basin: Possible fracture zones between Madagascar and Africa

Abstract

Continuous seismic profiling in the western Somali Basin reveals basement topography aligned approximately north to south. We interpret three buried ridges, approximately 50 km apart, approximately parallel to the Davie Ridge in the Mozambique Channel, as fracture zones along which Madagascar moved away from Africa. These data therefore support the northern paleopositions of Madagascar suggested by du Toit [1937] and Smith and Hallam [1970]. The ridges seem to provide an eastern barrier to sedimentation. The basement topography forming these fracture zones has a different origin from that of Chain Ridge.

Himalayan Uplift, Sea Level, and the Record of Bengal Fan Sedimentation at the ODP Leg 116 Sites

“…Formation of the Indian Ocean began in the Jurassic with the breakup of Gondwanaland into eastern (India, Madagascar, Australia, Antarctica) and western (Africa, Arabia, South America) portions. Eastern Gondwanaland moved to the south relative to Africa (Bunce and Molnar, 1977;Scrutton, 1978) with India and Madagascar left behind in the middle Cretaceous by the formation of a spreading center between India and Australia/ Antarctica (Markl, 1974(Markl, , 1978Larson et al, 1979) combined with the cessation of spreading at the Somali Basin spreading center (Segoufin and Patriat, 1980;Cochran, 1988).…”

The Africa–Madagascar connection and mammalian migrations

“…1). These conclusions were based primarily on magnetic anomaly identifications in the Somali Basin (Segoufin and Patriat, 1981;Rabinowitz et al, 1983) and is supported by paleomagnetic evidence , and physiographic, seismic and gravity anomaly evidence such as locations of fracture zones, salt diapirs or hot spot traces (Heirtzler and Burroughs, 1971;Rabinowitz, 1971; Bunce and Molnar, 1977;Scrutton, 1978;Rabinowitz et al, 1982;Storey et al, 1995). Prior to the collection of the magnetic anomalies, however, other investigators held differing opinions on the paleoposition of Madagascar relative to Africa.…”

Magmatism in Extensional Structural Settings

“…Incidentally, the south to southeastwards migration of Madagascar took place along this NW-SE fracture system presently extending offshore to the N-S Davie Ridge (Heirtzler and Burroughs 1971; Simpson et al 1974;Bunce and Molnar 1977;Segoufin and Patriat 1981;Mougenot et al 1986). Incidentally, the south to southeastwards migration of Madagascar took place along this NW-SE fracture system presently extending offshore to the N-S Davie Ridge (Heirtzler and Burroughs 1971; Simpson et al 1974;Bunce and Molnar 1977;Segoufin and Patriat 1981;Mougenot et al 1986).…”