A documentation on burrows in hard substrates of ferromanganese crusts and associated soft sediments from the Central Indian Basin

摘要

Substrates of ferromanganese encrustations collected from the hummocky topography of the Central Indian Basin (CIB) (lat, 12 degrees 25'-12 degrees 45'S, water depth between 5150 and 5300 m) are largely composed of indurated claystone and altered pumice fragments, which are extensively bioturbated, Both the ferromanganese-coated and uncoated relict burrows have been collected from the same locality. Mobile epibenthic megafauna, e.g. molluscs, echinoderms, etc. seem to be the main bioturbating organisms. The adjacent sediments on the sea floor also show numerous records of recent bioturbation activity. Thus presence of the ancient and modern burrows from the same locality on the ocean floor indicates a prolonged bioturbation activity in this part of the CIB and this may have been a continuous process, pre- and post-dating the initiation of the formation of ferromanganese oxides at this place. The intense and prolonged bioturbation activity of the benthic fauna reported here indicates that they could have facilitated the occurrence of ferromanganese nodules at the sediment-water interface. [References: 43]