Mascarene plateau, western Indian Ocean

The submarine Mascarene plateau, lying east and northeast of Madagascar in the west central Indian Ocean, extends as a faulted composite arc for 2300 km, from the Precambrian granitic 'microcontinent' of Seychelles bank southward through the coral-reef-capped volcanic structures (?) of Saya de Malha, Nazareth, and Cargados Carajos banks to the faulted Tertiary-Quaternary oceanic volcanic island Mauritius. Locally the aseismic plateau is buttressed by spurs, is steep-sided and angular in plan, or is extended, disrupted, or offset by cross-faulting. Other major structural elements in a sector centered on the Mascarene plateau are: (1) the seismically active Mid-Indian Ocean ridge and rift zone (including that portion known as the Carlsberg ridge) between the equator and its bifurcation near 23 degrees S.; (2) the angular and faulted Amirante trench lying between Seychelles bank and the Madagascar-Farquhar complex; (3) the east-west late Tertiary-Pleistocene Rodriguez ridge and its possible extension eastward as a fracture zone offsetting the Mid-Indian Ocean ridge; (4) the Mauritius trench, a 1400-km border deep trending southwest from east of Mauritius to 28 degrees S., 51 degrees E.