Komatiite

Komatiite ( /koʊˈmɑːtɪ.aɪt/) is a type of ultramafic mantle-derived volcanic rock. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content. Komatiite was named for its type locality along the Komati River in South Africa.

True komatiites are very rare and essentially restricted to rocks of Archaean age, with few Proterozoic or Phanerozoic komatiites known (although high-magnesian lamprophyres are known from the Mesozoic). This restriction in age is thought to be due to cooling of the mantle, which may have been up to 500 °C hotter during the early to middle Archaean (3.8 to 2.8 Ga). The early Earth had much higher heat production, due to the residual heat from planetary accretion, as well as the greater abundance of radioactive elements.

Geographically, komatiites are restricted in distribution to the Archaean shield areas. Komatiites occur with other ultramafic and high-magnesian mafic volcanic rocks in Archaean greenstone belts. The youngest komatiites are from the island of Gorgona on the Caribbean oceanic plateau off the Pacific coast of Colombia.


Read more about KomatiitePetrology, Mineralogy, Metamorphism, Geochemistry, Morphology and Occurrence, Economic Importance

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Superior Craton - Western Superior Province - North Caribou Terrane
... a voluminous mafic-ultramafic submarine sequence with intercalated komatiite and basalt that has been interpreted to be the product of a mantle plume in which the hot, deep, mantle-derived axis produced ... succession of quartzite, carbonate, banded iron formation and komatiite ... Within the greenstone belts, thin packages of quartz arenite-carbonate-komatiite have variably been interpreted as platformal cover strata and plume-related rift deposits ...
Kambalda Type Komatiitic Nickel Ore Deposits - Genetic Model
... sediments and volcanic rocks), from which the sulfide is melted by the high-temperature komatiite magma Dynamic System Ni-Cu-Co-PGE are chalcophile and ... Sulfides within the komatiite lava flows are denser than the silicate melt and tend to pool within topographic lows, which may be enhanced in the lava channel by proposed thermal erosion of the ...
Komatiite - Economic Importance
... The economic importance of komatiite was first widely recognised in the early 1960s with the discovery of massive nickel sulfide mineralisation at Kambalda, Western Australia ... Komatiite-hosted nickel-copper sulfide mineralisation today accounts for about 14% of the world's nickel production, mostly from Australia, Canada and South Africa ... Komatiites are associated with nickel and gold deposits in Australia, Canada, South Africa and most recently in the Guiana shield of South America ...
Kambalda Type Komatiitic Nickel Ore Deposits - Morphology
... be shown to be associated with the floor of a komatiite lava flow, concentrated within a zone of highest flow in the lava channel facies ... The lava channel is typically recognised within a komatiite sequence by Thickening of the basal flow of the komatiite sequence Increased MgO, Ni, Cu, and concomitant decrease in Zn ... either thermal erosion of the underlying substrate by the ultra-high temperature komatiite lava, or physical remobilisation during deformation ...
Winnipegosis Komatiite Belt
... The Winnipegosis komatiite belt, also called the Winnipegosis komatiites, is a volcanic belt composed of komatiite in central Manitoba, Canada ...