The Kerguelen volcanic Plateau: the second largest oceanic Igneous Province (LIP) on earth and a witness of the Indian Ocean opening
The geological evolution, geomorphological and geophysical data of the Kerguelen Plateau are summarized from the results of Indian Ocean Drilling Program (ODP) and Institut Paul Emile Victor (IPEV) scientific programs conducted during the last twenty years. This plateau is located in the Antarctic plate oceanic domain between 46 and 64°S, approximately equidistant from Africa and Australia. It is a Large Igneous Province (LIP) made up of thick sequences of lava flows rising 2000 to 3000 m above the seafloor, and generated by the activity of a hot spot, which seems to be presently located beneath Heard Island (where the active volcano Big Ben is located). The birth of the Plateau occurred in a mid-oceanic ridge setting (South East Indian Ridge, SEIR) 115 Ma ago. Since 43 Ma, the Kerguelen Plateau and Broken Ridge separated and the SEIR moved away northward from the plateau to reach its present intraplate setting. The plateau is subdivided into three parts: (1) the Northern Part, which carries the Kerguelen Islands, (2) the Central Part, which represents a basin located between Kerguelen and Heard islands with Upper Cretaceous sediments, and (3) the Southern Part which is characterized by a thick crust and which may contain old continental crust fragments. Available ages on sediments and lavas from several ODP legs indicate a short interval (110-115 Ma) for the formation of the uppermost igneous crust constituting the Kerguelen plateau.