Ontong Java Plateau

Ontong Java Plateau

Location of the Ontong Java Plateau in the Pacific Ocean

The Ontong Java Plateau is a huge oceanic plateau located in the Pacific Ocean, lying north of the Solomon Islands. The plateau covers an area of approximately 2,000,000 km² (770,000 sq mi), or roughly the size of Alaska, and reaches a thickness of up to 30 km (19 mi). The plateau is of volcanic origin, composed mostly of flood basalts. Although they are now separated by thousands of kilometres, Manihiki Plateau and Hikurangi Plateau were at the time of their origin part of the same large igneous province, forming the world's largest oceanic plateau. It extruded some 100 million km³ of magma, covering approximately 1% of the Earth's surface, in one of the largest volcanic events on Earth in the last 300 million years.

The Ontong Java Plateau was formed 125–120 million years ago possibly by the initial plume-head phase of a mantle plume center called the Louisville hotspot. The timing corresponds roughly to the early Aptian anoxic event in the oceans.

Most of the rocks that make up the plateaus have been dated to 125–119 million years ago, in the Lower Cretaceous Epoch, with some secondary volcanism occurring 20–40 million years later, in the Upper Cretaceous Epoch.

These plateaus were formed beneath the waters of the Pacific Ocean, and mostly still lie under the sea—although the collision of the Solomon Islands with the Ontong Java Plateau has lifted some of this plateau above sea level on the islands of Makira, Malaita and the northern half of Santa Isabel—along with the smaller islands of Ramos and Ulawa. Several large seamounts arise from the plateau, including the one capped by Ontong Java Atoll.

External links

• Large Igneous Provinces: Ontong Java Plateau, by Clive Neal, University of Notre Dame