Table of Contents
What happens when magma is low in silica?
Magma with low silica content is very fluid and easily erupts onto the surface through cracks and crevices at the surface. Over time the layers of lava build up a volcanic cone. Low silica volcanoes are characterized by “quiet” eruptions. Lava is able to easily flow out of the ground.
Why does silica make magma more viscous?
As the magma cools, more and more bonds are created, which eventually leads to the development of crystals within the liquid medium. Magmas that have a high silica content will therefore exhibit greater degrees of polymerization, and have higher viscosities, than those with low-silica contents.
Why would a volcano with high silica magma produce a more explosive eruption?
The density contrast between the magma and the surrounding rock causes more buoyant magma to rise. As the magma rises, the dissolved gases start to come out of the liquid and form bubbles. Silica molecules form a strong bond that permits entrapment of volcanic gases and promotes explosive volcanic eruptions.
What is the silica content of magma that has a low viscosity?
Non explosive eruptions are favored by low gas content and low viscosity magmas (basaltic to andesitic magmas)….Viscosity of Magmas.
| Summary Table | Magma Type | Rhyolitic |
|---|---|---|
| Solidified Rock | Rhyolite | |
| Chemical Composition | 65-75 SiO2 %, low in Fe, Mg, Ca, high in K, Na. | |
| Temperature | 650 – 800 oC | |
| Viscosity | High |
What type of magma has the greatest silica content?
As a result of its higher viscosity and gas content, intermediate magma builds up pressure below the Earth’s surface before it can be released as lava. Felsic magma has the highest silica content of all magma types, between 65-70%. Thick, viscous felsic magma can trap gas bubbles in a volcano’s magma chamber.
Which type of magma has the greatest amount of silica?
felsic magma has more silica and alumina content, which makes magma more viscous. It contains up to 70% of silica content . Its present in rhyolite rock.
Which magma has the most silica?
Rhyolitic magma
Rhyolitic magma contains the most silica. Silica is a chemical compound with the formula SiO2. Rhyolitic magma contains approximately 65 to 75…
Which rock has the greatest silica content?
Felsic rocks
Felsic rocks have the highest content of silica, and are predominantly composed of the felsic minerals quartz and feldspar. These rocks (granite, rhyolite) are usually light coloured, and have a relatively low density. Intermediate rocks have a moderate content of silica, and are predominantly composed of feldspars.