Summary Table
| Magma Type | Solidified Rock | Chemical Composition | Temperature | Viscosity |
| Basaltic | Basalt | 45-55 SiO 2 %, high in Fe, Mg, Ca, low i ... | 1000 - 1200 o C | Low |
| Andesitic | Andesite | 55-65 SiO 2 %, intermediate in Fe, Mg, C ... | 800 - 1000 o C | Intermediate |
| Rhyolitic | Rhyolite | 65-75 SiO 2 %, low in Fe, Mg, Ca, high i ... | 650 - 800 o C | High |
What type of lava erupts from stratovolcanoes?
Although dacitic-to-rhyolitic lavas typically erupt from stratovolcanoes, they are not as abundant as andesite lava. Instead, felsic eruptions from stratovolcanoes are more commonly explosive and associated with the generation of tephraand pyroclastic flows.
What is the difference between basalt and rhyolite?
Basalt and Rhyolite are the primary ingredients of some of most awe-inspiring eruptions that this planet has ever seen. The viscous rhyolite produces large explosive eruptions while the fluid basalt produces rivers of molten rock. Everything intermediate magma does, these two do better and a great deal better at that.
What are the main components of a super volcano?
The pressure of the magma chamber is the most obvious and necessary component of any large explosive eruption. Magma chambers in “Super volcanoes” are usually cool and not very active with some chambers only having 5-10% melt, the magmas from the chamber stay there thousands of years and evolve into silica rich magma.
Why do dacitic and rhyolitic magmas have explosive eruptions?
These explosive eruptions are a function of the high viscosities and high gas contents of dacitic and rhyolitic magmas. Such eruptions, however, will often deplete the magma source in dissolved gases.
What type of volcano has rhyolitic lava?
stratovolcanoesAlthough dacitic-to-rhyolitic lavas typically erupt from stratovolcanoes, they are not as abundant as andesite lava. Instead, felsic eruptions from stratovolcanoes are more commonly explosive and associated with the generation of tephra and pyroclastic flows.
What volcanoes produce rhyolite?
Only four eruptions of rhyolite have been recorded since the start of the 20th century: at the St. Andrew Strait volcano in Papua New Guinea and Novarupta volcano in Alaska as well as at Chaitén and Cordón Caulle volcanoes in southern Chile.
Where is rhyolitic magma found?
Rhyolite usually forms in continental or continent-margin volcanic eruptions where granitic magma reaches the surface. Rhyolite is rarely produced at oceanic eruptions.
What forms rhyolitic magma?
Rhyolitic magma forms as a result of wet melting of continental crust. Rhyolites are rocks that contain water and minerals that contain water, such as biotite. The continental crust must be heated above the normal geothermal gradient in order to melt.
What is a rhyolitic volcano?
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.
What is rhyolite formed from?
Rhyolite forms from magma that contains lots of silica (quartz) and is the fine-grained equivalent of granite.
What is the difference between basaltic volcanoes and rhyolitic volcanoes?
Thus, basaltic magmas tend to be fairly fluid (low viscosity), but their viscosity is still 10,000 to 100,0000 times more viscous than water. Rhyolitic magmas tend to have even higher viscosity, ranging between 1 million and 100 million times more viscous than water.
What are andesitic volcanoes?
Andesite (/ˈændəzaɪt/) is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
What type of rock is rhyolite?
rhyolite, extrusive igneous rock that is the volcanic equivalent of granite. Most rhyolites are porphyritic, indicating that crystallization began prior to extrusion.
What are the 3 types of magma that commonly form volcanoes?
The high temperatures and pressure under Earth's crust keep magma in its fluid state. There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition.
What are the 4 types of magma?
Because many of the properties of a magma (such as its viscosity and temperature) are observed to correlate with silica content, silicate magmas are divided into four chemical types based on silica content: felsic, intermediate, mafic, and ultramafic.
What type of volcano is Mt Mayon?
stratovolcanoMayon, located in the Philippines, is a highly active stratovolcano with recorded historical eruptions dating back to 1616. The most recent eruptive episode began in early January 2018 that consisted of phreatic explosions, steam-and-ash plumes, lava fountaining, and pyroclastic flows (BGVN 43:04).
Where is rhyolite found in the United States?
Mattapan Volcanic Complex - Rhyolite, melaphyre, agglomerate, and tuff. Mattapan Volcanic Complex is found in west and southwest part of Boston basin and beyond, and to the south in Blue Hills.
What type of volcano is Yellowstone?
Yellowstone CalderaAge of rock2,100,000–70,000 yearsMountain typeCaldera and supervolcanoVolcanic fieldYellowstone PlateauLast eruptionapproximately 640,000 years ago (caldera-forming); 70,000 years ago (in the caldera)11 more rows
What is a rhyolite caldera?
Rhyolite caldera complexes are the most explosive of Earth's volcanoes but often don't even look like volcanoes. They are usually so explosive when they erupt that they end up collapsing in on themselves rather than building any tall structure (George Walker has termed such structures "inverse volcanoes").
Where are basaltic volcanoes?
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 is the most important component of a volcano eruption?
The pressure of the magma chamber is the most obvious and necessary component of any large explosive eruption. Magma chambers in “Super volcanoes” are usually cool and not very active with some chambers only having 5-10% melt, the magmas from the chamber stay there thousands of years and evolve into silica rich magma. The portions of melt in the chamber would likely make a very slow ascent to the top and the lack of massive pressure would aid in that. Isolated high concentrations of melt in a large chamber is what likely leads to the smaller cinder cone forming eruptions in large calderas. These pockets of melt are likely generated by smaller intrusions, the melt generated from an intrusion can stay molten for an elevated time in chamber after the intrusion ends. It probably doesn’t take much to destabilize the chamber to the point of a smaller eruption.
How does a caldera affect the magma chamber?
The pressure generated by unrest, past or present, puts cumulative stress on the roof of the magma chamber. The effects of past unrest on the rock containing the magma fades after some time but in very active calderas, the effects are sustained for a longer period of time. Earthquakes and uplift put stress on the on the rock above leading to cracks and weakening any plug the volcano has over a period of thousands of years. The smaller eruptions in these calderas either increase or decrease the chance for a caldera forming eruptions. Smaller explosive eruptions can weaken the crust holding back the eruption as well as plug some vents while effusive eruption removes the vital pressure and eruptible magma while eventually being part of the same rock that is keeping the magma chamber under control. This phase will take thousand of years before the massive eruption and is the most benign sign but this is an important part of the phase of Super eruptions.
How does an explosive eruption affect the crust?
Smaller explosive eruptions can weaken the crust holding back the eruption as well as plug some vents while effusive eruption removes the vital pressure and eruptible magma while eventually being part of the same rock that is keeping the magma chamber under control.
What are the ingredients of the most awe-inspiring eruptions that this planet has ever seen?
Basalt and Rhyolite are the primary ingredients of some of most awe-inspiring eruptions that this planet has ever seen. The viscous rhyolite produces large explosive eruptions while the fluid basalt produces rivers of molten rock. Everything intermediate magma does, these two do better and a great deal better at that. The worst our planet can produce is something that no one truly understands to the fullest. Scientists can’t even agree on the climate affects of the Samalas eruption so the effects of a larger VEI 8 eruptions are not settled.
How does pressure affect eruption?
The pressure from the accumulated magma sets the stage for a large eruption, making the system more susceptible to external variables. The actual size of the eruption however depends on how much eruptible magma accumulated to the top and the strength of the crust.
What are the factors that cause caldera eruptions?
So many different factors play a role in large caldera forming eruptions, such as regional faulting, the pressure in the chamber, the strength of the rock, and possibly the hydrothermal system. I will explain how each factor plays a role in these massive eruptions. I would also like to say, once again, that I am not a volcanologist or scientist, I am just a person who loves volcanoes and has read up on a lot of research papers.
How do earthquakes affect volcanoes?
Earthquakes and uplift put stress on the on the rock above leading to cracks and weakening any plug the volcano has over a period of thousands of years. The smaller eruptions in these calderas either increase or decrease the chance for a caldera forming eruptions.
1. Andesitic Magma
Containing between 55 and 65 percent silica content, andesitic magma is firmly in the middle of the scale for silica, but not for everything.
2. Basaltic Magma
Right below andesitic magma on the silica content scale, basaltic magma has roughly 45 to 55 percent silica content. However, it actually is a step above andesitic in terms of temperature, ranging from 1,832 to 2,192 degrees Fahrenheit.
3. Felsic Magma
At 65 to 70 percent silica content, felsic magma is the thickest and gassiest of all magma types. It’s a “cool” 1,202 to 1,472 degrees Fahrenheit but the thickness and gas content means it’s the most explosive of magmas, often forming bubbles that then burst.
4. Intermediate Magma
This type of magma is often confused with andesitic magma because it frequently becomes andesite and has similar qualities to andesitic magma. However, intermediate magma remains around 60 percent silica.
5. Mafic Magma
Mafic magma is a close kin to basaltic magma, having a silica content of roughly 50 percent and temperatures of 1,832 to a blistering 3,632 degrees Fahrenheit.
6. Rhyolitic Magma
This is actually a hybrid form of magma, containing both basaltic magma and at least one other silica source. The qualities of this magma type can vary greatly as a result.
7. Ultramafic Magma
You’ll probably have to pay a visit to Io, Mercury, or Venus if you want to see this type of magma in action. That’s because it runs at a crisp 2,900 degrees Fahrenheit or hotter. Also known as komatiite magma, it’s runnier than any other type of magma but thankfully no longer flows on our planet.