What is the cooling history of andesite?
Andesite is a volcanic rock. It is fine-grained because it forms by the rapid cooling of magmas usually when it erupts onto the Earth’s surface and forms lava flows. Andesite forms from magma that contains less quartz (silica) than rhyolite but more than basalt.
What is the cooling history of andesite porphyry?
Slow cooling facilitates the growth of large mineral crystals in the rock. Andesite is a fine-grained rock that forms when the magma erupts onto the surface and crystallizes quickly. Andesite and diorite have a composition that is intermediate between basalt and granite.
What is cooling history of rhyolite?
Eruptions of granitic magma can produce rhyolite, pumice, obsidian, or tuff. These rocks have similar compositions but different cooling conditions. Explosive eruptions produce tuff or pumice. Effusive eruptions produce rhyolite or obsidian if the lava cools rapidly.
What is the origin of dacite?
Etymology. The word dacite comes from Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains (now modern Romania and Moldova) where the rock was first described.
When was andesite discovered?
In 2009, researchers revealed that andesite was found in two meteorites (numbered GRA 06128 and GRA 06129) that were discovered in the Graves Nunataks icefield during the US Antarctic Search for Meteorites 2006/2007 field season.
How is texture related to cooling history?
The texture of an igneous rock (fine-grained vs coarse-grained) is dependent on the rate of cooling of the melt: slow cooling allows large crystals to form, fast cooling yields small crystals.
What is the cooling history of a Phaneritic igneous rock?
Porphyritic:a mixture of large and small crystals – perhaps a two-stage cooling history with the large crystals (the phenocrysts) cooling slowly and the small crystals (the groundmass) cooling more quickly. The rock to the right has a phaneritic texture; individual grains can be seen.
What kind of cooling history do porphyritic textures indicate?
Porphyritic texture indicates the magma body underwent a multi-stage cooling history, cooling slowly while deep under the surface and later rising to a shallower depth or the surface where it cooled more quickly.
Is dacite extrusive or intrusive?
Dacite is a felsic extrusive rock, intermediate in composition between andesite and rhyolite. It is often found associated with andesite, and forms lava flows, dikes, and, in some cases, massive intrusions in the centres of old volcanoes. Dacite is the volcanic equivalent of granodiorite.
What is andesite used for in real life?
Andesite may be used as aggregate or fill, but it is not ideal for concrete applications because it is high in silica, and causes alkali-silica reactivity in the concrete. Andesitic volcanism is associated closely with porphyry copper deposits and it is a host rock for much of the world’s copper ore.
How is andesitic magma formed?
Andesitic magma is formed through wet partial melting of the mantle. The mantle under the ocean has contact with water. When subduction, or continental plates pulling away from one another, occurs, the mantle will heat up and water is pushed into it.
Can cooling change the composition of andesitic plagioclase?
Therefore, kinetic effects due to cooling significantly change the plagioclase composition with remarkable petrological implications for the solidification of andesitic lavas and dikes. The glass-forming ability (GFA) of the andesitic melt has been also quantified in a critical cooling rate ( Rc) of ~ 37 °C/min.
What is the formation of andesite?
Andesite Formation 1 Fractional crystallization of a mafic parent magma. 2 Partial melting of crustal material. 3 Magma mixing between the magmas in a magma reservoir
What is an andesitic rock?
Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Martian crust . The name andesite is derived from the Andes mountain range, where this rock type is found in abundance.
What is the A/CNK of andesite?
The andesite from Šiatorska Bukovinka is metaluminous, medium-potassic rock with A/CNK = 0.95 and A/NK = 2.38. The Mg/ (Mg + Fe2+) ratio was recalculated after the conversion of all Fe2O3 to FeO.