boninite


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boninite

[′bän·ə‚nīt]
(petrology)
An andesitic rock that contains much glass and abundant phenocrysts of bronzite and less of olivine and augite.
References in periodicals archive ?
This ophiolite includes magmas from MORB to Boninite and suggest that it was formed in an arc/back arc system.
Rocks snatched from the volcano include boninite lavas, a chemically distinct type of lava previously found only around extinct volcanoes that erupted more than 1 million years ago.
The West Mata Volcano is producing boninite lavas, believed to be among the hottest on Earth in modern times, and a type seen before only on extinct volcanoes more than one million years old.
According to University of Hawaii geochemist Ken Rubin, the active boninite eruption provides a unique opportunity to study magma formation at volcanoes, and to learn more about how Earth recycles material where one tectonic plate is subducted under another.
Swarms of these dikes are exposed in the Bonin Islands, and one lava type from this environment, boninite, was named for the islands.
However, boninites contain the chemical imprint of a source region invaded by fluids derived from a subduction zone (for example, they contain 10 times more water than mid-ocean ridge lavas).
This area hosts a band of low titanium tholeiite and boninite mafic volcanic rocks believed to have been emplaced in high heat flow rifting environments, important for the formation of massive sulphide deposits.
Subsequently Stern and Bloomer (1992) established a link between initiation of subduction, boninite production and ophiolite formation.
1979, Boninites, komatiites, and ophiolitic basalts: Namre, v.
1983, Boninite petrogenesis: chemical and Nd-Sr isotopic constraints: Earth and Planetary Science Letters, v.
Geochemical analyses show that the schist is a high-Ca boninite (high-Mg andesite to basalt).
Because some Archean komatiites are associated with calc-alkaline volcanic rocks and boninites, Grove and Parman (2004) argued that like recent boninites, komatiites may result from wet melting above a subduction zone.