How do you classify ultramafic rocks?

Amphibole-bearing ultramafic rocks These rocks can be classified using the olivine – pyroxene – hornblende (Ol – Px – Hbl) ternary diagram, where Px comprises both ortho- and clinopyroxene. IUGS classification of ultramafic rocks with olivine, pyroxene, and hornblende.

What are the characteristics of ultramafic rocks?

Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium …

What is an example of ultramafic?

An igneous rock with a very low silica content and rich in minerals such as hypersthene, augite, and olivine. These rocks are also known as ultramafic rocks. Examples include: peridotite, kimberlite, lamprophyre, lamproite, dunite, and komatiite. Shown in the photo is a specimen of peridotite.

What is the composition of ultramafic rocks?

Ultramafic metamorphic rocks result from the metamorphism of mantle rocks and some oceanic crust and contain dominantly magnesium, silicon, and carbon dioxide, with smaller amounts of iron, calcium, and aluminum.

What are ultramafic igneous rocks?

« Back to Glossary Index. An igneous rock with extremely low silica composition, being made of almost all olivine and pyroxene. Ultramafic rocks contain very low amount of silica and are common in the mantle. Primary ultramafic rocks are komatiite (extrusive) and peridotite (intrusive).

What is mafic and ultramafic?

In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with between 55 and 65 percent silica are intermediate; those with between 45 and 55 percent silica are mafic; and those with less than 45 percent are ultramafic.

What is the texture of ultramafic rocks?

Porphyroclastic. -The most common texture in the ultramafic xenoliths that we have studied is characterized by kinked or strained porphyroclasts in a finer- grained (average less than 2 mm) matrix of recrystallized, unstrained (polygonized) grains (fig. 7). Olivine and pyroxenes occur as relict and matrix grains.

What is the difference between ultramafic and mafic?

What is ultramafic mean?

adjective. geology. (of igneous rock) composed of a very high percentage of magnesium and iron.

What are mafic and ultramafic rocks?

What type of rock is mafic?

mafic rock, in geology, igneous rock that is dominated by the silicates pyroxene, amphibole, olivine, and mica. These minerals are high in magnesium and ferric oxides, and their presence gives mafic rock its characteristic dark colour.

What is meant by the term ultramafic?

Are ultramafic rocks dense?

Normal oceanic crust tends to be mafic or ultramafic, of high density, 2.85-3.0 g/cm , typically 6-10 km thick, based on refraction data.

What is the difference between mafic and felsic?

Either in describing rocks or lava, mafic means that the lava or rock has less silica while felsic implies that the lava or rock has the most silica. 6. Mafic rocks are darker in color than felsic rocks.

What is the difference between mafic and ultramafic rocks?

Where is ultramafic rock found?

Many surface exposures of ultramafic rocks occur in ophiolite complexes where deep, mantle-derived rocks have been obducted onto continental crust along and above subduction zones.

What is the difference in ultramafic and mafic?

What is ultramafic igneous rock?

What is mafic and ultramafic rocks?

What is the difference between ultramafic and felsic?

How can ultramafic rocks be classified?

Ultramafic and related mafic rocks can conveniently be classified in terms of the tectonic environment in which they were emplaced.

What are intrusive ultramafic rocks?

Intrusive ultramafic rocks are often found in large, layered ultramafic intrusions where differentiated rock types often occur in layers. Such cumulate rock types do not represent the chemistry of the magma from which they crystallized.

Are there any ultramafic volcanoes?

Subvolcanic ultramafic rocks and dykes persist longer, but are also rare. There is evidence of ultramafic rocks elsewhere in the solar system. Many of the lavas being produced on Io, a moon of Jupiter, may be ultramafic, as evidenced by their temperatures which are higher than terrestrial mafic eruptions.

What is the difference between ultramafic and Phanerozoic rocks?

The majority of ultramafic rocks are exposed in orogenic belts, and predominate in Archaean and Proterozoic terranes. Ultramafic magmas in the Phanerozoic are rarer, and there are very few recognised true ultramafic lavas in the Phanerozoic.