What is basaltic crust?
Basalt is the dark, heavy volcanic rock that makes up most of the world’s oceanic crust. Some of it erupts on land, too, but to a first approximation, basalt is an oceanic rock. Compared to the familiar granite of the continents, basalt (“ba-SALT”) is darker, denser and finer grained.
What’s the meaning of basaltic?
(bə-sôlt′, bā′sôlt′) n. 1. A hard, dense, dark igneous rock composed chiefly of plagioclase feldspar, pyroxene, and olivine, and often having a glassy appearance.
What is basaltic magma?
There are three major types of magma. Basaltic (or mafic) magma predominates in nonexplosive volcanic eruptions. It is a high-temperature magma (1,200 °C [about 2,200 °F]) characterized by flowing lava, and it is made up of about 45–55 percent silica (SiO2) by weight.
How is basaltic crust formed?
Currently oceanic crust forms by the eruption of basaltic lava along a globe-encircling network of mid-ocean ridges. More than 18 cubic kilometers of rock are produced every year by this process. The slab of newly formed crust rides on top of an outer layer of the mantle, which together make up the rigid lithosphere.
What is basalt made up of?
Basalts are composed of minute grains of plagioclase feldspar (generally labradorite), pyroxene, olivine, biotite, hornblende and <20% quartz. Nepheline or leucite may associate or proxy the feldspar giving rise to verities with special names. The ferromagnesian minerals are mainly amphibole and rarely biotite.
What are the main differences between basaltic and granitic magma?
Igneous rocks are formed by the crystallisation of a magma. The difference between granites and basalts is in silica content and their rates of cooling. A basalt is about 53% SiO2, whereas granite is 73%. Intrusive, slowly cooled inside the crust.
Where is basalt found?
It is found all over Earth, but especially under the oceans and in other areas where Earth’s crust is thin. It formed in the Isle Royale-Keweenaw region because of the Midcontinent Rift. Most of Earth’s surface is basalt lava, but basalt makes up only a small fraction of continents.
What does basalt look like?
Basalt is usually dark grey to black in colour, due to its high content of augite or other dark-coloured pyroxene minerals, but can exhibit a wide range of shading. Some basalts are quite light-coloured due to a high content of plagioclase, and these are sometimes described as leucobasalts.
Where is basaltic magma formed?
Basaltic magma is commonly produced by direct melting of the Earth’s mantle, the region of the Earth below the outer crust. On continents, the mantle begins at depths of 30 to 50 km. Shield volcanoes, such as those that make up the Islands of Hawai’i, are composed almost entirely of basalt.
What are characteristics of basalt?
basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in colour, and comparatively rich in iron and magnesium. Some basalts are quite glassy (tachylytes), and many are very fine-grained and compact.
Where basalt is found?
What is granite and basalt?
Basalt is an igneous rock or volcanic rock that is produced by the rapid cooling of lava which is rich in magnesium and iron. It is formed at the surface where it will Barden from lava. Granite is a coarse- or medium-grained intrusive igneous rock with a felsic composition.
What is the definition of basaltic?
Define basaltic. basaltic synonyms, basaltic pronunciation, basaltic translation, English dictionary definition of basaltic. n. 1. A hard, dense, dark igneous rock composed chiefly of plagioclase feldspar, pyroxene, and olivine, and often having a glassy appearance. 2.
Where does the term basalt come from?
The modern petrological term basalt describing a particular composition of lava-derived rock, originates from its use by Georgius Agricola in 1546 in his work De Natura Fossilium.
What is the difference between basalt and basaltic magma?
Basalt is an igneous rock, i.e., one that has congealed from a molten state. Basaltic magma is derived by partial melting of the peridotite that is found in the asthenosphere asthenosphere
What is an example of a basaltic plain?
For example, the bulk of the plains of Venus, which cover ∼80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars .