What type of magma is considered intermediate and composition?
Types of magma are determined by chemical composition of the magma. Three general types are recognized: Basaltic magma — SiO2 45-55 wt%, high in Fe, Mg, Ca, low in K, Na. Andesitic magma — SiO2 55-65 wt%, intermediate.
What type of volcano has intermediate lava?
Stratovolcanoes Stratovolcanoes show inter-layering of lava flows and pyroclastic material, which is why they are sometimes called composite volcanoes.
What is intermediate lava?
Intermediate lava Intermediate or andesitic lavas contain 52% to 63% silica, and are lower in aluminium and usually somewhat richer in magnesium and iron than felsic lavas. Intermediate lavas form andesite domes and block lavas and may occur on steep composite volcanoes, such as in the Andes.
What are intermediate volcanoes?
Intermediate composition (andesitic) lavas are common where two plates converge to produce a subduction zone, especially along continental margins like western South America. Intermediate lavas are more viscous than the mafic lava which forms shield volcanoes (see above) and normally contain more volatiles.
What is andesitic lava?
Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesites contain crystals composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende.
What is mafic magma?
Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows. Includes andesites (57-63 percent SiO2), basaltic andesites (53-57 percent SiO2), and basalts (47-53 percent SiO2).
Which volcanoes have mafic lava?
Mafic lava flows can travel quite far before solidifying completely, and the type of volcano that forms from mafic lava is called a shield volcano (Figure 9.9). Shield volcanoes are very broad at the base and have relatively gentle slopes.
What are mafic volcanoes?
Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows.
What is mafic lava composed of?
Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows. Includes andesites (57-63 percent SiO2), basaltic andesites (53-57 percent SiO2), and basalts (47-53 percent SiO2).
Where is intermediate magma found?
Intermediate magma most commonly transforms into andesite due to the transfer of heat at convergent plate boundaries. Andesitic rocks are often found at continental volcanic arcs, such as the Andes Mountains in South America, after which they are named.
What is basaltic lava?
Basaltic lava is another term for mafic lava. Mafic lava is molten rock that is enriched in iron and magnesium and low in silica. When mafic lava cools on the earth's surface, it forms basalt, which is why mafic lava is commonly called 'basaltic lava.
Is andesite an intermediate?
Andesite is an extrusive rock intermediate in composition between rhyolite and basalt. Andesite lava is of moderate viscosity and forms thick lava flows and domes.
What is an intermediate igneous rock?
Igneous Rocks by Composition Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). There is little or no quartz.
Which rock has an intermediate composition?
Intermediate is a composition between felsic and mafic. It usually contains roughly-equal amounts of light and dark minerals, including light grains of plagioclase feldspar and dark minerals like amphibole.
Is magma felsic or mafic?
| MAGMA COMPARISON | ||
|---|---|---|
| Property | Mafic Magma | Felsic Magma |
| Composition | iron, magnesium | silica, aluminum |
| Color | darker | lighter |
| Density | higher (3 g/cm3) | lower (2.7 g/cm3) |
How is intermediate magma made?
Intermediate magma most commonly transforms into andesite due to the transfer of heat at convergent plate boundaries. Andesitic rocks are often found at continental volcanic arcs, such as the Andes Mountains in South America, after which they are named.
How is intermediate magma produced?
Intermediate and felsic magmas form around convergent margins with a subduction zone. 3. these volcanic mountain chains often form arc shapes, because that is the shape produced when a flat plate (tectonic plate) intersects a sphere (Earth).
What is granitic lava?
Granitic magmas are very different from basaltic magmas. They have about 20 percent more silica, and the minerals in granite (mica, amphibole) have a lot of water in their crystal structures. Granitic magmas are mostly exclusive to regions of continental crust.
What is rhyolite lava?
Rhyolitic lavas are viscous and tend to form thick blocky lava flows or steep-sided piles of lava called lava domes. Rhyolite magmas tend to erupt explosively, commonly also producing abundant ash and pumice.
Is basalt intermediate?
Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite are intermediate, with an average silica content of 59 percent; gabbro and basalt are mafic, with an average silica content of 48 percent; and peridotite is …
Which igneous rocks are intermediate?
Typical intermediate rocks include andesite, dacite and trachyandesite among volcanic rocks and diorite and granodiorite among plutonic rocks.
What is felsic magma?
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3.
What is the magma composition of a composite volcano?
Composite volcano magma is felsic, which means it contains silicate-rich minerals rhyolite, andesite, and dacite. Low-viscosity lava from a shield volcano, such as might be found in Hawaii, flows from fissures and spreads.
Is rhyolite an intermediate?
Rhyolite. Medium silica content (intermediate). A fine-grained volcanic rock of granitic composition.
What igneous rocks are intermediate?
Typical intermediate rocks include andesite, dacite and trachyandesite among volcanic rocks and diorite and granodiorite among plutonic rocks.
Are composite volcanoes basaltic?
Shield volcanoes are formed by basaltic magma, typically above a mantle plume, whereas the stratovolcanoes (sometimes referred to as composite volcanoes) are formed by andesitic/rhyolitic magma.
Which of the following is a composite type of volcano?
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra.
Is basalt mafic felsic or intermediate?
Igneous Rocks by Composition
| Coarse-Grained Textures | Fine-Grained Textures |
|---|---|
| Peridotite = Ultramafic | Komatiite (Ultramafic, but too rare to worry about at this point in your life) |
| Gabbro = Mafic | Basalt = Mafic |
| Diorite = Intermediate | Andesite = Intermediate |
| Granite = Felsic | Rhyolite = Felsic |
What is intermediate igneous rock?
In igneous petrology an intermediate composition refers to the chemical composition of a rock that has 52-63 wt% SiO2 being an intermediate between felsic and mafic compositions.
Which of the following is a volcanic intermediate composition igneous rock?
Intermediate igneous volcanic rock is: basalt.