Distribution and Origin of Seamounts in the Central Indian Ocean Basin

Approximately 200 seamounts of different dimensions have been identified, from multibeam bathymetry maps of the Central Indian Ocean Basin (CIOB) (9°S to 16°S and 72°E to 80°E), of which 61% form eight chains that trend N-S. The seamounts are clustered above and below 12°S latitude. Area II (9°–12°S) shows a concentration of smaller seamounts (≤400 m height), and area I (12°–15°S) has a mixed population (including both less and more than 400 m height). Inspite of the differences in their height, the seamounts of these eight chains are morphologically (slope angle, flatness, basal width) corelatable. Furthermore, we suggest that height-width ratio could be useful in identifying the style of seamount eruption. The seamount chains in the CIOB probably originated from propagative fractures and were produced between 61 and 52 Ma (chrons A26 to A23) as a result of the interaction between the conjugate crusts of the Central Indian and Southeast Indian Ridges during the Indo-Eurasian collision event.

Keywords:

• Seamounts
• CIOB fracture-zone
• seamount-chain

We thank the Director, NIO, for permission to publish. The data were collected under the “Survey of Polymetallic Nodule” project funded by DOD, New Delhi. We are indebted to the referees for a patient and thorough assessment of the study and to Prof. N. K. Saxena (Editor-in-Chief) for encouragement to carry out the revisions. P.D. acknowledges the Council of Scientific and Industrial Research, New Delhi, for financial assistance in the form of a Research Fellowship. This is NIO's contribution #3968.