Depressed continental hypsometry behind oceanic trenches: A clue to subduction controls on sea-level change

Abstract

In the western Pacific there is a strong spatial correlation between areas predicted to be depressed because of subducted slabs and the location of flooded continental crust. Elevation of continental crust behind oceanic trenches and above subducting slabs is 400-500 m lower than the global average, and hypsometry of this crust is shallower and flatter than the global average, especially for crust just below sea level. Reduction in continental elevation in such areas is dependent on distance from the trench: the closer crust is to the trench (and hence to the slab), the greater is the reduction in average elevation. Shape of the hypsometry is consistent with a finite-element model with active sedimentation above a slab that becomes older with time. The results strongly suggest that dynamic distortion of Earth's surface by slabs may have been a fundamental control on location of shallow seas through geologic time.