Magellan Rise (ocean plateau)

07°04.1′N 176°49.5′W^[1]Magellan Rise is an oceanic plateau in the Pacific Ocean,^[1] which covers a surface area of 500,000 square kilometres (190,000 sq mi).^[2] There is another geological structure with the same name west from the Marshall Islands.^[3]

The Magellan Rise has been called a large igneous province^[a] by Coffin and Endholm 2001^[5] and was emplaced 145 million^[4] or 135-128 million years ago, possibly as a consequence of intense volcanism at a former triple junction.^[6] Alternatively, the Rise was formed by a mantle plume^[7] linked to the deep "JASON superplume",^[8] or from the interaction of a spreading ridge with a plume.^[9] Candidate mantle plumes are the Easter hotspot^[10] and the Foundation hotspot.^[11]

The volume of rocks in the Magellan Rise is very uncertain, but may be in the range of 1,800,000 cubic kilometres (430,000 cu mi)^[2] to 19,740,000 cubic kilometres (4,740,000 cu mi).^[12] It apparently developed first on the Phoenix Plate before being transferred onto the Pacific Plate 125 million years ago.^[13] The Magellan Rise has never risen to shallow depths, at least since the Cretaceous, and it is covered by sediments of Tithonian/Berriasian to Quaternary age.^[1] The sediments include chalk, chert, limestone^[14] (including fossil belemnites,^[15] molluscs and polychaetes^[16]), phosphorites^[17] and volcanic ash from the Ontong Java Plateau, which were emplaced during the Selli Event.^[18]

Notes

1. Other such provinces in the Pacific Ocean are the Hess Rise, Manihiki Plateau, Mid-Pacific Mountains, Ontong Java Plateau and Shatsky Rise.^[4]