Does rhyolitic magma have violent eruptions?
Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas). The explosive bursting of bubbles fragments the magma into clots of liquid that cool as they fall through the air.
What is rhyolitic 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.
How does rhyolitic magma flow?
Rhyolite is a felsic extrusive rock. Due to the high silica content, rhyolite lava is very viscous. It flows slowly, like tooth paste squeezed out of a tube, and tends to pile up and form lava domes.
What type of eruption will rhyolitic lava cause?
Pelean eruptions are considered violently explosive. Plinian – These eruptions result from a sustained ejection of andesitic to rhyolitic magma into eruption columns that may extend up to 45 km above the vent.
What type of volcano has rhyolitic magma?
stratovolcanoes
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.
What are the characteristics of rhyolitic magma?
Rhyolitic magma is high in potassium and sodium but low in iron, magnesium, and calcium. It occurs in the temperature range of about 650oC to 800oC (1202oF to 1472oF).
Where would you expect to find rhyolitic magma?
Rhyolite is common along convergent plate boundaries, where a slab of oceanic lithosphere is being subducted into the Earth’s mantle beneath overriding oceanic or continental lithosphere. It can sometimes be the predominant igneous rock type in these settings.
How is rhyolitic lava formed?
Rhyolite is an extrusive igneous rock, formed from magma rich in silica that is extruded from a volcanic vent to cool quickly on the surface rather than slowly in the subsurface. It is generally light in color due to its low content of mafic minerals, and it is typically very fine-grained (aphanitic) or glassy.
What volcanoes have rhyolitic magma?
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. You will also come to understand the relationship between volcanic phenomena and plate tectonics.
What is rhyolitic magma made of?
Rhyolite is extrusive equivalent of granite magma. It is composed predominantly of quartz, K–feldspar and biotite. It may have any texture from glassy, aphanitic, porphyritic, and by the orientation of small crystals reflecting the lava flow.
What is granitic magma?
Laboratory experiments suggest that when rocks with the composition of continental crust start to melt at temperature and pressure conditions found in the lower crust, a granitic liquid is formed, with 30 percent partial melting. …
Where does rhyolitic magma come from?
Rhyolite usually forms in continental or continent-margin volcanic eruptions where granitic magma reaches the surface. Rhyolite is rarely produced at oceanic eruptions.
When does rhyolite come from a lava eruption?
Rhyolite or obsidian are made when the lava flows more smoothly from the eruption, but it takes especially quick cooling to produce obsidian from the smooth flow. All four of these igneous rock types can come from the same eruption.
What kind of lava flows do rhyoliticlavas produce?
Rhyoliticlavas are viscous and tend to form thick blocky lava flows or steep-sided piles of lava called lava domes. Rhyolitemagmastend to erupt explosively, commonly also producing abundant ashand pumice. Glossary Terms
Which is more explosive obsidian or rhyolite lava?
Rhyolite or obsidian are made when the lava flows more smoothly from the eruption, but it takes especially quick cooling to produce obsidian from the smooth flow. All four of these igneous rock types can come from the same eruption. Volcanos produced from granitic magma are rare, but they can be the most explosive of all eruptions.
Why do dacitic and rhyolitic volcanoes erupt?
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. De-gassed magma can then rise to the surface and extrude in a less violent fashion, as dacite to rhyolite lava.