Subsidence of the Kerguelen Plateau: The Atlantis Concept

Ocean Drilling Program Leg 119 and 120 results from the Southern Kerguelen Plateau provide important constraints on the subsidence history of this large igneous province. Following emplacement of the plateau at —110 Ma, sedimentary facies indicate that portions of the feature remained above sea level or in shallow water for up to 40 m.y. I use previously determined age-depth relationships for oceanic lithosphere to determine the level of emplacement for five sites on the Southern Kerguelen Plateau. If thermal subsidence was the dominant tectonic process affecting the Southern Kerguelen Plateau following emplacement, then large portions of the feature were emplaced and began subsiding far above sea level. This resulted in significant erosion and redeposition of volcanic material mixed with biogenic sediment, and a gradual development of facies from terrestrial through terrigenous to shallow water and pelagic. I propose the "Atlantis" concept for this early evolution of the Kerguelen Plateau and of other large igneous provinces that produced a sedimentary record intermediate between continental and oceanic.