Minerals Report - International Seabed Authority

The richest gold bearing seafloor deposit found to date is located at
Conical Seamount in the territorial waters of Papua New Guinea close to Lihir
Island. Maximum gold concentrations in samples collected from the summit
plateau of this seamount (2.8 km basal diameter at 1,600 m water depth, top at
1,050 m) range up to 230 ppm with an average of 26 ppm for 40 samples
analysed 79, 80 .
Table 5: Primary Gold Grades in Polymetallic Massive Sulphides from the Modern
Seafloor
Immature Back-Arc Ridges
(Intermediate to felsic volcanics)
Lau Basin
Okinawa Trough
Central Manus Basin
Eastern Manus Basin
Woodlark Basin
Mature Back-Arc Ridges
(MOR-type volcanics)
Mariana Trough
North Fiji Basin
Mid-Ocean Ridges
(MORB)
Conical Seamount (PNG)
(Magmatic-epithermal system)
Range
Au (ppm)
Average (N)
0.01-28.7
0.01-14.4
0.01-52.5
1.30-54.9
3.80-21.1
0.14- 1.7
0.01-15.0
0.01-10.7
0.01-30.0
2.8
3.1
30.0
15.0
13.1
0.8
2.9
103
40
10
26
6
11
42
INTERNATIONAL SEABED AUTHORITY 125
1.2
26.0
8. Resource Potential Of Seafloor Sulphide Deposits
1,259
Out of the more than 100 sites of hydrothermal mineralisation
currently known at the modern seafloor, only about 10 deposits may have
sufficient size and grade to be considered for future mining, although
information on the thickness of most of those sulphide deposits is not yet
available (Table 6). These potential mine sites include the Atlantis II Deep in
40