komatiite

The rock type komatiite is particularly diagnostic of those volcanic sequences and is almost exclusively restricted to the Archean Eon. The cratons were tectonically stabilized by voluminous granite intrusions toward the end of the Archean and were then covered by clastic sediments, some of which contain economically important…

Komatiite, a magnesium-rich, high-temperature volcanic rock derived from very hot mantle (part of the Earth between the crust and the core), was extruded in abundance during the early Precambrian when the heat flow of the Earth was higher than it is today. Blueschist, which contains…

…high-magnesium, high-temperature mafic magma called komatiite erupted from hot spots. Since most komatiites are only found in Archean regions, they are thought to be evidence for Earth being hotter than when it was initially formed. The youngest komatiite was recently discovered on the island of Gorgona, Colom.

…a magnesium-rich lava called a komatiite (named for the Komati River in South Africa).