PETROLOGY OF SEAMOUNTS IN THE CENTRAL INDIAN-OCEAN BASIN - EVIDENCE FOR NEAR-AXIS ORIGIN

Previous studies on the distribution and morphology of ancient seamoun t chains (> 50 Ma) in the Central Indian Ocean basin (CIOB) indicated their generation from the fast spreading Southeast Indian Ridge. Here we describe the petrology of some of these seamounts. Fresh glass vene ers of pillow basalts from these seamounts were analyzed by electron m icroprobe. The rocks show a low content of TiO2 and FeO and moderate M g# suggesting slow eruption of a minimally fractionated N-MORB magma. In terms of chemistry and morphology, CIOB seamounts are indistinguish able from seamounts across slow spreading MAR and fast spreading EPR.