Oceanic trench the level of the surrounding oceanic floor. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km/yr. There are approximately of convergent plate margins, mostly around the Pacific Ocean—the reason for the reference “Pacific-type” margin—but they are also in the eastern Indian Ocean, with relatively short convergent margin segments in the Atlantic Ocean and in the Mediterranean Sea. Globally, there are over 50 major ocean trenches covering an area of 1.9 million km or about 0.5%
Ontong Java Plateau Ontong Java Plateau The Ontong Java Plateau (OJP) is a huge oceanic plateau located in the south-west Pacific Ocean, north of the Solomon Islands. The OJP was emplaced 120 Ma with a much smaller volcanic event 90 Ma. Two other south-west Pacific plateaus, Manihiki and Hikurangi, now separated from the OJP by Cretaceous ocean basins, are of similar age and composition and probably formed as a single plateau and a contiguous large igneous province together with the OJP. When emplaced this Ontong Java-Manihiki-Hikurangi plateau covered 1% of Earth's surface and represented a volume of of basaltic magma. This "Ontong Java