Seafloor massive sulfide deposits or SMS deposits, are modern equivalents of ancient

volcanogenic massive sulfide ore deposit Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and created by volcanic-associated hydrothermal events in submarine environments. Th ...

s or VMS deposits. The term has been coined by mineral explorers to differentiate the modern deposit from the ancient. SMS deposits were first recognized during the exploration of the deep oceans and the mid ocean ridge spreading centers in the early 1960s. Deep ocean research

submersible A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of in ...

bathysphere The Bathysphere (Ancient Greek, Greek: , , "deep" and , , "sphere") was a unique spherical deep-sea submersible which was unpowered and lowered into the ocean on a cable, and was used to conduct a series of dives off the coast of Bermuda from 19 ...

s and remote operated vehicles have visited and taken samples of black smoker chimneys, and it has been long recognised that such chimneys contain appreciable grades of Cu, Pb, Zn, Ag, Au and other trace metals. SMS deposits form in the deep ocean around submarine volcanic arcs, where hydrothermal vents exhale sulfide-rich mineralising fluids into the ocean. SMS deposits are laterally extensive and consist of a central vent mound around the area where the hydrothermal circulation exits, with a wide apron of unconsolidated sulfide silt or ooze which precipitates upon the seafloor. Beginning about 2008, technologies were being developed for

deepsea mining Deep sea mining is a growing subfield of experimental seabed mining that involves the retrieval of minerals and deposits from the ocean floor found at depths of or greater. As of 2021, the majority of marine mining efforts are limited to shall ...

of these deposits.

Minerals

Mineralization in submarine magmatic-hydrothermal systems is a product of the chemical and thermal exchange between the ocean, the lithosphere, and the magmas emplaced within it. Different mineral associations precipitate during the typical stages of mineralization that characterize the life span of such systems. Minerals present in a hydrothermal system or a fossil volcanogenic massive sulfide deposit are deposited passively or reactively. Mineral associations may vary (1) in different mineralized structures, either syngenetic (namely, passive precipitation in chimneys, mounds and stratiform deposits) or epigenetic (structures that correspond to feeder channels, and replacements of host rocks or pre-existing massive sulfide bodies), or ''structural zonation'', (2) from proximal to distal associations with respect to venting areas within the same ''stratigraphic horizon'', or horizontal zonation, (3) from deep to shallow associations (''i.e.'', stockworks to mounds), or ''vertical zonation'', (4) from early and climactic to late stages of mineralization (dominated by sulfides, and sulfates or oxides, respectively), or ''temporal zonation'', and (5) in various volcano sedimentary contexts, depending essentially on the composition of volcanic rocks and, ultimately, on the tectonomagmatic context. The most common minerals in ore-bearing associations of volcanogenic massive sulfide deposits (non-metamorphosed or oxidized) and their modern analogues are

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

pyrrhotite Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it ...

chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mo ...

, covellite,

sphalerite Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Va ...

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cry ...

tetrahedrite Tetrahedrite is a copper antimony sulfosalt mineral with formula: . It is the antimony endmember of the continuous solid solution series with arsenic-bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the t ...

- tennantite,

marcasite The mineral marcasite, sometimes called “white iron pyrite”, is iron sulfide (FeS2) with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Bot ...

, realgar,

orpiment Orpiment is a deep-colored, orange-yellow arsenic sulfide mineral with formula . It is found in volcanic fumaroles, low-temperature hydrothermal veins, and hot springs and is formed both by sublimation and as a byproduct of the decay of another ...

proustite Proustite is a sulfosalt mineral consisting of silver sulfarsenide, Ag3 As S3, known also as light red silver or ruby silver ore, and an important source of the metal. It is closely allied to the corresponding sulfantimonide, pyrargyrite, from w ...

pyrargyrite Pyrargyrite is a sulfosalt mineral consisting of silver sulfantimonite, Ag3SbS3. Known also as dark red silver ore or ruby silver, it is an important source of the metal. It is closely allied to, and isomorphous with, the corresponding sulfars ...

, wurtzite,

stannite Stannite is a mineral, a sulfide of copper, iron, and tin, in the category of thiostannates. Background The chemical formula Cu2 Fe Sn S4. Zinc commonly occurs with the iron and trace germanium may be present. Stannite is used as an ore of tin, ...

(

sulfides Sulfide ( British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds ...

), Mn oxides, cassiterite,

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With ...

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of ...

(

oxides An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the ...

barite Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

anhydrite Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with t ...

(

sulfates The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ar ...

calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scra ...

siderite Siderite is a mineral composed of iron(II) carbonate (FeCO3). It takes its name from the Greek word σίδηρος ''sideros,'' "iron". It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Zinc, magnesium an ...

(

carbonates A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

)

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

and native gold, and are differently distributed in the various associations schematized above. The most common hydrothermal alteration assemblages are chloritic (including Mg-rich ones) and

phyllic alteration Phyllic alteration is a hydrothermal alteration zone in a permeable rock that has been affected by circulation of hydrothermal fluids. It is commonly seen in copper porphyry ore deposits in calc-alkaline rocks. Phyllic alteration is characterise ...

(dominated by “

sericite Sericite is the name given to very fine, ragged grains and aggregates of white (colourless) micas, typically made of muscovite, illite, or paragonite. Sericite is produced by the alteration of orthoclase or plagioclase feldspars in areas th ...

”, mostly

illite Illite is a group of closely related non-expanding clay minerals. Illite is a secondary mineral precipitate, and an example of a phyllosilicate, or layered alumino-silicate. Its structure is a 2:1 sandwich of silica tetrahedron (T) – alumina ...

), and also silicification, deep and shallow

talc Talc, or talcum, is a clay mineral, composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent ...

ose alteration, and ferruginous (including Fe oxides, carbonates and sulfides) alteration.

Economic importance

Economic extraction of SMS deposits is in the theoretical stage, the greatest complication being the extreme water depths at which these deposits are forming. However, apparent vast areas of the peripheral areas of these black smoker zones contain a sulfide ooze which could, theoretically, be vacuumed up off the seafloor.

Nautilus Minerals Nautilus Minerals Inc. was an underwater mineral exploration company headquartered in Toronto, Ontario, Canada. It was the first company to commercially explore deep sea mining of the seafloor for massive sulfide systems, a potential source of hi ...

Inc. (Nautilus) was engaged in commercially exploring the ocean floor for copper, gold, silver and zinc seafloor massive sulphide (SMS) deposits, and mineral extraction from an SMS system. Nautilus' Solwara 1 Project located at 1,600 metres water depth in the

Bismarck Sea The Bismarck Sea (, ) lies in the southwestern Pacific Ocean within the nation of Papua New Guinea. It is located northeast of the island of New Guinea and south of the Bismarck Archipelago. It has coastlines in districts of the Islands Region, ...

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

, was an attempt at the world's first deep-sea mining project, with first production originally expected in 2017. However, the company went bankrupt in 2019 after failing to secure funding for the project.

Known SMS deposits

Deep ocean drilling, seismic

bathymetry Bathymetry (; ) is the study of underwater depth of seabed, ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of w ...

surveys and mineral exploration deep sea drilling has delineated several areas worldwide with potentially economically viable SMS deposits, including: * Lau Basin ** Kermadec Volcanic Arc ** Colville Ridge *

Okinawa Trough The (also called , literally China-Ryukyu Border Trough ) is a seabed feature of the East China Sea. It is an active, initial back-arc rifting basin which has formed behind the Ryukyu arc-trench system in the West Pacific. It developed where t ...

North Fiji Basin The North Fiji Basin (NFB) is an oceanic basin west of Fiji in the south-west Pacific Ocean. It is an actively spreading back-arc basin delimited by the Fiji islands to the east, the inactive Vitiaz Trench to the north, the Vanuatu/ New Hebrid ...

(see d'Entrecasteaux Ridge) *

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

References

{{reflist

External links

''The dawn of deep ocean mining'', Steven Scott, Feb. 2006
* Bertram C., A. Krätschell, K. O'Brien, W. Brückmann, A. Proelss, K. Rehdanz (2011). Metalliferous sediments in the Atlantis II deep -Assessing the geological and economic resource potential and legal constraints. Resources Policy 36(2011), 315–329. Economic geology Oceanography Sedimentary rocks

Minerals

Economic importance

Known SMS deposits

See also

References

External links