Kerguelen Plateau

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Location of the plateau - white spot is Kerguelen Island

The Kerguelen Plateau is an underwater volcanic large igneous province (LIP) in the Indian Ocean. It lies about 3000 km to the southwest of Australia and is nearly three times the size of Japan. The plateau extends for more than 2200 km in a northwest-southeast direction and lies in deep water. The plateau was produced by a hot spot or mantle plume starting with or following the breakup of Gondwanaland about 130 Mya. There is a small portion of the plateau that breaks sea level, forming the Kerguelen Islands, Heard Island and the McDonald Islands. Intermittent volcanism continues on Heard and McDonald islands. Symmetrically located across the Indian Ocean ridge and due west of Australia, is the Broken Ridge underwater volcanic plateau which was at one time contiguous with the Kerguelen Plateau prior to rifting by the mid-ocean ridge. To the north of Broken ridge lies the linear Ninety East Ridge which continues almost due north into the Bay of Bengal and is considered to be a hotspot track.

The Kerguelen Plateau was formed starting 110 million years ago from a series of large volcanic eruptions. The presence of soil layers in the basalt with included charcoal and conglomerate fragments of gneiss indicate that much of the plateau was above sea level as what is termed a microcontinent for three periods between 100 million years ago and 20 million years ago. The so-called Kerguelen continent might have been covered with lush ferns, small dinosaurs would have hidden in the undergrowth stalking their prey and moist with tropical humidity about 50 million years ago. The Kerguelen continent finally sank 20 million years ago and is now 1 - 2 km below sea level. It has sedimentary rocks similar to the ones found in Australia and India, indicating they were once attached.