Tectonic Reactivation in the Indian Ocean:Evidences from Seamount Morphology and Manganese , Nodule Characteristics

The Central Indian Ocean Basin (CIOB) was subjected to tectonic reacti, vation in geological past which is unusual for a basin occurring on an apparently , single tectonic plate. ENE-WSW trending latitude parallel zone of reactivation across the central part of the basin is reported. Distinct difference in characters of seamounts, . manganese nodules and bottom sediment are found in this deformed central part as . compared to those from northern and southern parts of th'is basin. Much lower ratio of height to basal width (h/Wb) of seamounts; and presence of several guyots in this' ; central part are reported. Abundance of smaller. spheroidal, smooth textured nodules and absence of index radiolarian zone I fossil, coupled with sediment erosion of to several centimeters indicate activity of west-bound Antarctic Bottom Water (ABW) , and other turbulent water masses that later passed through the reactivated central part. The cause of this deformation is attributed to wrench.faulting as part of large scale tectonic reactivation during late Miocene.