Seabed topography and distribution of manganese nodules in the Central Indian Ocean

Abstract

The relationship between seabed topography and distribution of nodules, recovery of free fall grab samplers, nodule size and chemical composition of manganese nodules in the Central Indian Ocean have been studied. Nodule abundance was greater (4.2 kg/m2) in rugged topography (hill tops, slopes, and valleys) than in the abyssal plains (2.3 kg/m2). Similarly, the recovery of grab samplers was more from rugged topographic areas (66%) than from the plains (47.5%). Nodules of <40 mm size was greater in number in all the topographic environments. Mn/Fe ratio was least (2.2) for nodules from hill taps whereas it was maximum for those from the plains (4.4). Cu+Ni+Co compositioin varied antipathetically with nodule abundance in the Central Indian Ocean.