The amirante ridge and trench system in the Indian Ocean: The southern termination of the NW Indian subduction

Abstract

The Amirante Ridge and Trench System forms a 600-km-long arcuate structure in the Mascarene Basin (Indian Ocean), whose origin remains enigmatic. Here, I provide a paleogeographic reconstruction of the NW India margin for the Late Cretaceous–Paleocene interval, compiling information from ophiolites surrounding the Arabian Sea and data collected at sea. This reconstruction shows that the Amirante Ridge and Trench System constitutes the southern termination of a ∼1500-km-long subduction, which used to run along the NW Indian margin during the Late Cretaceous–Paleocene. The dislocation of the NW Indian subduction, recorded at the Amirante Ridge and Trench System and the Bela ophiolites, may have played a role in the plate reorganization event recorded at 73–63 Ma.