A pair of seamount chains in the central Indian basin, identified from multibeam mapping

Seamounts are major physiographic features on the ocean floor. Their study is important to the understanding of the tectonic history of the seafloor. Over 150 seamounts were identified during the multibeam (Hydrosweep system) mapping of the Central Indian Basin. The average depth in this basin is around 5,100 m. Heights of these features range from 200 to 1700 m, with varying morphologies ranging from pointed cones to flat lops and cratered tops. Two distinct chains of seamounts and abyssal hills were found. Chain A, along 75°26'E, has seven features trending along N3°E. Two of the seamounts in this chain are 1,200 m high and occupy large areas (275 and 170 km²). One of these seamounts has a cratered top. The crater is 1 km wide and 180 m deep. Two features in Chain A have a high summit width and are flattopped. Chain B, along 75°43'E, has six features, trending N10°E. The maximum height of the seamounts in this chain is 1,150 m. The flatness values (ratio of summit width to basal width) increase from north to south. Features in the north have pointed cone shapes, while features in the south have flat tops. The southernmost feature has a cratered top, 0.8 km wide and 110 m deep. The trend of the seamounts is parallel to the absolute motion of the Indian plate. Their origin may be related to the rear‐axis fast‐spreading systems.

Keywords:

• crater
• fracture zone
• morpology
• multibeam system
• seamount chains