A slab in depth: Three-dimensional geometry and evolution of the Indo-Australian plate

Abstract

Geoscientists use plate tectonics to explain many aspects of both continental evolution and evolution of the planet as a whole. The subduction of material at convergent plate boundaries forms a fundamental component to the theory of plate tectonics. Plates, continents, subduction zones, and spreading centers all exhibit motion and geometric evolution, so to try and resolve the past geometries of the planet, geologists have utilized plate tectonic reconstructions. Here we present a three-dimensional image of the subducted Indo-Australian plate below southeast Asia and show that the geometry of the subducted slab at depth is intimately related to the geometric evolution of SE Asia over the past 50 Ma, including the collision of India with the Asian continent. We show how the once semicontinuous subducting Indo-Australian plate has been segmented during collision between India, Australian, and the subduction margin to the north. Thus we have found that the geometry of the subducted plate should form a key component to the interpretation of the evolution of Earth's surface, as complexities and evolution of the subducted plate are manifest in the evolution of the overriding plate.