Diamantina Fracture Zone Ridge Plateau. All these features are mirrored by corresponding topography on the other side of the Southeast Indian Ridge. Broken Ridge Plateau was formed at the ridge together with the Kerguelen Plateau. Diamantina Fracture Zone was first detected by and RV Argo in 1960. It is named after , which did further exploration in 1961. The Diamantina Deep is the zone's deepest location, located about 1 125 km West-South-West of Perth, Western Australia, at . This is not the deepest point in the Indian Ocean: the CIA's Physical Map of the World lists the Java Trench as such. On the
Philippine Trench a M 8.2. The trench reaches one of the greatest depths in the ocean, third only to the Mariana trench and the Tonga trench. Its deepest point is known as Galathea Depth and reaches 10,540 meters (34,580 ft) or (5,760 fathoms). Sedimentation of the Philippine trench contains slightly metamorphosed, calc-alkalic, basic, ultrabasic rock and sand grains. The southern area of the trench contains homogenous, blue, clay silt and was poor in lime. Sand grains that were also found contained fresh basaltic andesite. The sediments found in the trenches are hypothesized to have been deposited by turbidity currents. A turbidity current