Minerals Report - International Seabed Authority
Minerals Report - International Seabed Authority Minerals Report - International Seabed Authority
While noting that the continuity of seafloor sulphide outcrops are difficult to determine, and that the depth of possible mineralisation is difficult to assess, Professor Herzig stated that estimates for several deposits on the mid-ocean ridges range between 1-100 million tonnes. He also stated that the largest deposits are found on failed and heavily sedimented but still hydrothermally active oceanic ridges. He reiterated the importance of drilling for resource estimation, informing the workshop that drilling carried out by the Ocean Drilling Programme during Legs 139 and 169 at the sedimentcovered Middle Valley deposit on the northern Juan de Fuca Ridge has delineated about 8-9 million tonnes of sulphide ore. He further informed participants that during both legs of the drilling programme, about 100 m of massive sulphides and 100 m of stock work were drilled at the Bent Hill site. At this site, he stated that the results of the drilling programme indicate that the sub seafloor stock work zone is underlain by a stratified Cu-rich horizon (“deep copper zone”) with copper grades ranging up to 17 %. With regard to the known sizes of seafloor sulphides deposits and compared to their counterparts on land (VMS), Professor Herzig made the following observations: The TAG hydrothermal mound located at 3,650 meter water depth at the Mid-Atlantic Ridge 26°N was drilled during Ocean Drilling Programme Leg 158 in 1994 to a total depth of 125 m. It was estimated that the active TAG mound contains about 2.7 million tonnes of sulphides ore above the seafloor and approximately 1.2 million tonnes of sulphides in the sub seafloor stock work. A comparison of the size of seafloor sulphides deposits with some of the ancient ore bodies and ore districts on land indicates that extremely large deposits such as Kidd Creed in Canada (135 million tonnes) or Neves Corvo in Portugal (262 million tonnes) are yet to be discovered at the seafloor. Among the known marine sulphides deposits, Professor Herzig stated that the largest known marine sulphide deposit is the Atlantis II Deep in the Red Sea, which was discovered more than ten years before the first black INTERNATIONAL SEABED AUTHORITY 26
smoker at the East Pacific Rise. The Atlantis II Deep mineralisation he further stated, consists of metalliferous muds, instead of massive sulphides. This difference, he stated, is a consequence of the high salinity that hydrothermal fluids acquire by circulation through thick miocene evaporites at the flanks of the Red Sea rift. He reported that detailed evaluation of the 40 square kilometre deposit has delineated 94 million tonnes of dry ore with metal grades of 2.0% Zinc, 0.5% Copper, 39 ppm silver, and 0.5 ppm gold which results in a total precious metal content of roughly 4,000 tonnes of silver and 50 tonnes of gold. As previously stated by Professor Rona, Professor Herzig informed the workshop that a pilot mining test of the metalliferous muds in the Atlantis II Deep, at a depth of 2,000 m, has shown that this deposit can be successfully mined. With regard to the precious metal content of seafloor massive sulphides, Professor Herzig noted that high gold grades have been found in a number of seafloor deposits at the mid-ocean ridges, in particular in samples from the back-arc spreading centres. He stated that the average gold content of deposits at the mid-ocean ridges range from 0.2 ppm gold up to 2.6 ppm gold, with an overall average of 1.2 ppm gold. In volcanic-dominated, sediment-free deposits, high-temperature (350 o C) black smoker chimneys composed of copper and iron sulphides typically contain less than 0.2 ppm gold. Here, much of the gold is lost to a diffuse hydrothermal plume. He further noted that higher concentrations of primary gold have been found in lower-temperature (
- Page 2 and 3: Workshop on Minerals Other than Pol
- Page 4 and 5: Published in Jamaica 2004 by the In
- Page 6 and 7: Chapter 6* Impact of the Developmen
- Page 8 and 9: PART 4 REGULATORY AND PROMOTIONAL F
- Page 10 and 11: The Authority designates one of two
- Page 12 and 13: deposits and gas hydrates of the co
- Page 14 and 15: Prof. Chris German, Challenger Divi
- Page 16 and 17: Mr. Sven Petersen, Research Associa
- Page 18 and 19: SECRETARIAT Ambassador Satya N. Nan
- Page 20 and 21: is to submit “an application that
- Page 22 and 23: that was established to help protec
- Page 24 and 25: on the continental margin. He state
- Page 26 and 27: with the German firm Preussag. As p
- Page 28 and 29: metre or metres of these black smok
- Page 30 and 31: nodules in terms of these metals -
- Page 32 and 33: Professor Herzig stressed however t
- Page 36 and 37: asal diameter at 1,600 m water dept
- Page 38 and 39: discovery of the new hydrothermal s
- Page 40 and 41: esearch cruises dedicated to ferrom
- Page 42 and 43: global mid-ocean ridge system. He p
- Page 44 and 45: athymetric map of the seafloor. A s
- Page 46 and 47: were encouraging. In the course of
- Page 48 and 49: that this matter was sensitive, he
- Page 50 and 51: complete a preliminary evaluation o
- Page 52 and 53: metals - nickel, cobalt, manganese,
- Page 54 and 55: 12. Issues to be taken into account
- Page 56 and 57: entities. Many of them included min
- Page 58 and 59: In this regard, the Secretary-Gener
- Page 60 and 61: According to Dr. Vysotsky, as estim
- Page 62 and 63: With regard to current knowledge ab
- Page 64 and 65: Dr. Corbett gave a brief account of
- Page 66 and 67: River resulting in the introduction
- Page 68 and 69: Ms. Zaamwani pointed out that as th
- Page 70 and 71: geochemical and geotechnical survey
- Page 72 and 73: of its continental shelf through bi
- Page 74 and 75: also stated, is similar to that of
- Page 76 and 77: Chapter 7 Technical requirements fo
- Page 78 and 79: Table 1: Classification of marine m
- Page 80 and 81: Volcanogenic Metalliferous sediment
- Page 82 and 83: deposits, including massive sulphid
While noting that the continuity of seafloor sulphide outcrops are<br />
difficult to determine, and that the depth of possible mineralisation is difficult<br />
to assess, Professor Herzig stated that estimates for several deposits on the<br />
mid-ocean ridges range between 1-100 million tonnes. He also stated that the<br />
largest deposits are found on failed and heavily sedimented but still<br />
hydrothermally active oceanic ridges. He reiterated the importance of drilling<br />
for resource estimation, informing the workshop that drilling carried out by<br />
the Ocean Drilling Programme during Legs 139 and 169 at the sedimentcovered<br />
Middle Valley deposit on the northern Juan de Fuca Ridge has<br />
delineated about 8-9 million tonnes of sulphide ore. He further informed<br />
participants that during both legs of the drilling programme, about 100 m of<br />
massive sulphides and 100 m of stock work were drilled at the Bent Hill site.<br />
At this site, he stated that the results of the drilling programme indicate that<br />
the sub seafloor stock work zone is underlain by a stratified Cu-rich horizon<br />
(“deep copper zone”) with copper grades ranging up to 17 %.<br />
With regard to the known sizes of seafloor sulphides deposits and<br />
compared to their counterparts on land (VMS), Professor Herzig made the<br />
following observations:<br />
The TAG hydrothermal mound located at 3,650 meter water<br />
depth at the Mid-Atlantic Ridge 26°N was drilled during<br />
Ocean Drilling Programme Leg 158 in 1994 to a total depth<br />
of 125 m. It was estimated that the active TAG mound<br />
contains about 2.7 million tonnes of sulphides ore above the<br />
seafloor and approximately 1.2 million tonnes of sulphides<br />
in the sub seafloor stock work.<br />
A comparison of the size of seafloor sulphides deposits with<br />
some of the ancient ore bodies and ore districts on land<br />
indicates that extremely large deposits such as Kidd Creed<br />
in Canada (135 million tonnes) or Neves Corvo in Portugal<br />
(262 million tonnes) are yet to be discovered at the seafloor.<br />
Among the known marine sulphides deposits, Professor Herzig stated<br />
that the largest known marine sulphide deposit is the Atlantis II Deep in the<br />
Red Sea, which was discovered more than ten years before the first black<br />
INTERNATIONAL SEABED AUTHORITY 26
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