Table of Contents
- 1 Where are ultramafic rocks found?
- 2 Is komatiite an igneous rock?
- 3 Is komatiite magnetic?
- 4 Where are mafic rocks found?
- 5 What minerals are in Komatiite?
- 6 Who discovered Komatiite?
- 7 Where is mafic magma found?
- 8 What are the location of mafic or basaltic?
- 9 Where do you find komatiites?
- 10 What is the chemical composition of komatiite?
- 11 Are komatiites produced by plumes or melting processes in the upper mantle?
Where are ultramafic rocks found?
Earth’s mantle
Ultramafic rocks are primarily found in Earth’s mantle. Since the mantle represents about 84\% of the Earth’s volume, most of the Earth is actually ultramafic.
Is komatiite an igneous rock?
Komatiites are very rare igneous rocks. They are one variety of extrusive ultramafic igneous rock (although a komatiite in Canada has been interpreted to be an intrusive sill). They are named after the Komati River in South Africa, the type locality. Komatiite is an exceedingly rare type of lava.
Why is komatiite important?
In addition to the information they provide about the tectonics and the thermal evolution of Archean Earth, komatiites are economically important because they host locally significant magmatic Ni-sulfide (Ni-Cu-PGE) mineralization.
Is komatiite magnetic?
(1990) point out, gold occurs in a wide variety of host rocks. All the deposits studied here are hosted by strongly magnetic volcanic and sedimentary rocks such as komatiites, tholeiites and BIF.
Where are mafic rocks found?
Mafic minerals crystallize at higher temperatures, which Bowen’s Reaction Series describes. Therefore, rocks composed of mafic minerals are formed at higher temperatures. They are found in locations deep within the earth and also in tectonic spreading environments, like the seafloor.
Where is kimberlite rock found?
Generally speaking, kimberlites are found only in cratons, the oldest surviving areas of continental crust, which form the nuclei of continental landmasses and have remained virtually unchanged since their formation eons ago.
What minerals are in Komatiite?
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, and frequently displays spinifex texture composed of large dendritic plates of olivine and pyroxene.
Who discovered Komatiite?
Komatiites were first identified by Richard and Morris Viljoen in 1969, in the Archean greenstone belt in the Barberton Mountain land of South Africa as a distinctive and “new” class of magnesium-rich (20-30 wt \% MgO) volcanic rocks.
What is the cooling rate of komatiite?
Donaldson (1982) estimated that cooling rates in the A3 layer of a typical 5–10 m thick komatiite flow were <1 C/h. In contrast, to reproduce the dendritic mor- phology of platy spinifex olivine crystals in normal dynamic cooling laboratory experiments requires cooling rates >50 C/h (Donaldson, 1982).
Where is mafic magma found?
Magma collects in magma chambers in the crust at 160 kilometers (100 miles) beneath the surface of a volcano. The words that describe composition of igneous rocks also describe magma composition. Mafic magmas are low in silica and contain more dark, magnesium and iron rich mafic minerals, such as olivine and pyroxene.
What are the location of mafic or basaltic?
A. Basaltic magmas most commonly erupt on the ocean floor at places where two tectonic plates move away from each other. 1. Such places are called spreading centers or mid-ocean ridges.
Where is kimberlite found in Australia?
South Australia
Most of the known kimberlites in South Australia are located in the Adelaide Fold Belt (Colchester, 1972;Ferguson and Sheraton, 1979;Stracke et al., 1979;Scott Smith et al., 1984), where they occur as a semi- continuous, northwest trending dyke-swarm ( Fig. 1).
Where do you find komatiites?
Komatiites are fairly rare rocks, but they are found throughout the world in places such as Canada and South Africa. Most komatiites were formed billions of years ago in the Archean (approximately 2.5 to 3.8 billion years ago).
What is the chemical composition of komatiite?
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, and frequently displays spinifex texture composed of large dendritic plates of olivine and pyroxene .
When were komatiite lavas first discovered?
Most komatiite lavas were produced in the Archean (approximately 2.5 to 3.8 billion years ago). 3. A rock type whose hotly– and wetly– debated origin sometimes galvanizes geologists to shouting matches, fist fights, and drinking contests.
Are komatiites produced by plumes or melting processes in the upper mantle?
Recently though, an old debate ( Allegre, 1982) has been rekindled that argues these magmas are not produced by plumes, but rather by hydrous melting processes in the upper mantle ( Parman & Grove, 2001). Komatiites were first recognized in the late 1960s in the Barberton Mountainland greenstone belt in South Africa ( Viljoen & Viljoen, 1969a,b).