BASINAL SEAMOUNTS AND SEAMOUNT CHAINS OF THE CENTRAL INDIAN-OCEAN - PROBABLE NEAR-AXIS ORIGIN FROM A FAST-SPREADING RIDGE

Hydrosweep mapping of crust in the Central Indian Ocean Basin reveals abundant volcanoes ocurring both as isolated seamounts and linear seam ount chains parallel to flow lines. Their shapes, sizes and overall st yle of occurrence are indistinguishable from near-axis seamounts in th e Pacific. Evidence from seamount morphology, distributions and petrog raphy of dredged samples suggests that they were generated near the fa st-spreading Southeast Indian Ridge at 50-60 Ma. If so, this style of near-axis seamount generation may be a result of fast-spreading rate r ather than a peculiarity of the present Pacific spreading ridges. In f act, the results of several recent studies, taken together, suggest th at the style of axis/near-axis seamount volcanism varies systematicall y as a function of spreading rate.