Workshop on the Establishment of a Geological Model of ...

the Indian Ocean. Using 8 ships and 60 cruises, researchers had taken samples at regular intervals
throughout the original application area of 150,000 square kilometres, of which half had later been
relinquished to the Authority. India had used the results of this survey to select blocks of least economic
potential that were then relinquished to the Authority.
The survey had shown that nodules were most abundant in areas of the roughest topography. In
addition, whereas abundance varied over short distances, metal content tended to remain steady over broad
areas. Indian scientists had found that their abundance figures increased by an average of 132 per cent when
they shifted from one grab sampler to another, demonstrating the importance of adjusting estimates
according to the equipment used for sampling. The metal resource (cobalt, copper and nickel) in the 75,000‐
square‐kilometre Indian area had been estimated at 9.4 million tonnes.
Dr. Ryszard Kotliński, Director‐General of IOM, headquartered in Szczecin, Poland, presented results
from a research cruise conducted in 2001 in the 75,000‐square‐kilometre exploration area allocated to his
organization in the CCZ. The aim of the cruise had been to acquire data related to the identification of nodule
resources, including a detailed analysis of location, shapes, sizes and composition, and their relation to the
surrounding environment. Nodules were most abundant at the sediment‐water interface, a gummy, fluid
layer from 2 to 12 centimetres thick. Abundance was greatest at depths of 4,300‐4,500 metres below the
ocean surface. Nodules varied greatly in distribution, size and composition over the exploration area, with
concentrations of nickel and cobalt highest in the north, copper in the centre and manganese in the south.
Dr. Valeri Yubko, Deputy Director of the Okeanglofizika Research Institute, Yuhzmorgeologiya,
discussed nodule distribution over the CCZ as a whole, with reference to differences between northern,
central and southern segments. He found metal concentration patterns throughout the zone to be generally
similar to those described for the IOM area. The northern segment of the CCZ was characterized by fewer
and smaller nodules, while abundance was greatest in the central segment. These differences corresponded
to a north‐south gradation in surface‐sediment zones. Seabed topography was characterized by long hills,
abyssal valleys and inter‐valley plateaus running north‐south. Slopes greater than 6 degrees were devoid of
nodules.
He revealed recently discovered evidence of hydrothermal vent activity, including polymetallic
sulphides, along the undefined fracture at the centre of the CCZ.
Dr. Wenzheng Lu, of the Second Institute of Oceanography, State Oceanic Administration, Hangzhou,
China, told of results from eight cruises conducted by COMRA from 1991 to 1998 in the Chinese‐allocated
area at the western margin of the CCZ, an area divided into two non‐contiguous sectors. Linear north‐south
furrows marked the seabed of the eastern sector, along with seamounts scattered like a string of beads. In
the west, five seamount chains up to 1,000 metres high were separated by basins and furrow areas. The
sectors also differed in tectonic activity, with volcanism prominent in the west and faulting in the east. The
west had a higher abundance of nodules but the east had a higher grade of metals.
Factors controlling nodule development in the area included the Antarctic Bottom current, which
delivered extra oxygen conducive to nodule formation; the availability of metallic minerals from undersea
volcanoes, and the presence of the CCD at 4,900 metres, just above the most favourable depth of nodule
generation.
9. Biological Inputs
The final presentation addressed the ways in which knowledge of ocean biology might contribute to a
geological model. Dr. Craig R. Smith, professor in the Department of Oceanography of the University of
Hawaii (United States), described some of the main features of the CCZ deep‐sea environment. He noted
that about 90 per cent of the seabed was covered by sediment. The habitat was vast and largely continuous,
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