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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 produced by volcanic-associated hydrothermal vents in submarine environments. [2] [3] [4] These deposits are also sometimes called volcanic-hosted massive sulfide (VHMS) deposits
In 2005, Neptune Resources NL, a mineral exploration company, applied for and was granted 35,000 km 2 of exploration rights over the Kermadec Arc in New Zealand's Exclusive Economic Zone to explore for seafloor massive sulfide deposits, a potential new source of lead-zinc-copper sulfides formed from modern hydrothermal vent fields.
The best nickel deposits are formed where sulfide accumulates in the base of lava tubes or volcanic flows — especially komatiite lavas. Komatiitic nickel-copper sulfide deposits are considered to be formed by a mixture of sulfide segregation, immiscibility, and thermal erosion of sulfidic sediments.
In an ideal exhalative model, hot dense brines flow to depressed areas of the ocean topography where they mix with cooler, less dense, sea water, causing the dissolved metal and sulfur in the brine to precipitate from solution as a solid metal sulfide ore, deposited as layers of sulfide sediment. [1]
Massive sulfide deposits are ore deposits that have significant stratiform ore bodies consisting mainly of sulfide minerals.Most massive sulfide ore deposits have other portions that are not massive, including stringer or feeder zones beneath the massive parts that mostly consist of crosscutting veins and veinlets of sulfides in a matrix of pervasively altered host rock and gangue.
Bacterial colonies and deposits can form concentration cells, causing and enhancing galvanic corrosion. [3] Bacterial corrosion may appear in form of pitting corrosion, for example in pipelines of the oil and gas industry. [4] Anaerobic corrosion is evident as layers of metal sulfides and hydrogen sulfide smell.
After being exposed to air and water, oxidation of metal sulfides (often pyrite, which is iron-sulfide) within the surrounding rock and overburden generates acidity. Colonies of bacteria and archaea greatly accelerate the decomposition of metal ions, although the reactions also occur in an abiotic environment.
World-wide distribution of MVT deposits (red), clastic sediment-hosted (green), and unclassified (blue) lead-zinc deposits. Source: USGS. Carbonate-hosted lead-zinc ore deposits are important and highly valuable concentrations of lead and zinc sulfide ores hosted within carbonate (limestone, marl, dolomite) formations and which share a common genetic origin.