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granitic magmas contain more silica than basaltic magmas.
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∙ 13y ago
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Why are granitic igneous rocks light in color?
granitic igneous rocks are light colored because of a lower density than basaltic rocks
What type of eruptions do mafic magmas cause?
Basaltic magmas are associated with fissure eruptions creating lava flows spilling out from cracks in the crust. This is because basaltic magmas are more viscous and contain a lower concentration of gases than rhyolitic magma and therefore are unable to build up sufficient pressure to produce explosive eruptions.
What is the relationship in the silicon content and the viscosity of magma?
There is an inverse relationship between magma viscosity and silicon content. Lavas erupting from basaltic volcanoes (like Hawaii) have a much lower viscosity and are much hotter than those erupted by volcanoes whose magmas are rich in silicon. There may be up to 8 orders of magnitude viscosity difference between basaltic magmas (SiO2 contents or about 45 %) and rhyolitic magmas (SiO2 > 70 %).
Light colored igneous rocks are less what than dark igneous rocks?
basaltic rocks are darker because they are more dence granitic rocks are less dence so they are lighter
What percentage of lava on Earth is basaltic?
Volumetrically, most lava is of basaltic composition. Basaltic melts have overall lower gas contents and are more fluid than their andesitic-to-rhyolitic counterparts. Their higher fluidity (lower viscosity) is a product of their lower SiO2 (silica) contents. When gases exsolve from basaltic melts they are allowed to rise unimpeded through the fluid magma without a significant build up of gas pressure. This results in relatively calm, nonexplosive eruptions, and a preponderance of lava. In contrast, when gases exsolve from felsic magmas, their upward mobility is impeded by the high viscosity of the melt. This results in the buildup of gas pressure, which generates explosive eruptions associated with a preponderance of pyroclastic ejecta. The low viscosity of basaltic lavas allows them to be extruded over great distances, often producing high-volume lava flows with low aspect ratios (ratio of thickness to area). Under the right conditions, de-gassed felsic magmas can also erupt lava in a nonviolent manner. However, felsic lavas tend to be much thicker than basaltic lavas and have much higher aspect ratios.source:www.geology.sdsu.edu
Why are granitic igneous rocks lighter in color than basaltic rocks?
Because granitic rocks are poor in iron and magnesium, which gives basaltic rocks it dark color.
Will rhyolitic magmas erupt at lower temperatures than basaltic magmas?
Yes, rhyolitic magmas are several hundred °C colder than basaltic magmas. This is because the melting point of a rhyolitic magma is much lower than that of basaltic magma. Instead of heating up rhyolitic magma much above its melting point it will ascend and either crystallize in the Earth's interior as a pluton or erupt.
Why are granitic igneous rocks light in color?
granitic igneous rocks are light colored because of a lower density than basaltic rocks
How is continental lithosphere different oceanic lithosphere?
Continental lithosphere is thicker and less dense than oceanic lithosphere. Continental crust is primarily composed of granitic rock while oceanic crust is composed primarily of basaltic rock.
What type of eruptions do mafic magmas cause?
Basaltic magmas are associated with fissure eruptions creating lava flows spilling out from cracks in the crust. This is because basaltic magmas are more viscous and contain a lower concentration of gases than rhyolitic magma and therefore are unable to build up sufficient pressure to produce explosive eruptions.
What is the difference between oceanic and continental plates?
Continental plates are thicker and less dense. Continental plates are mainly granitic in composition. Oceanic plates are mainly basaltic in composition. The rock of continental plates is on average, much older than the rock of the oceanic plates. The oceanic plate underlies the oceans, and the continental plate makes up the land masses. Continental plates do not subduct at convergent plate boundaries.
How is basaltic lava different from granitic lava?
Basaltic lava is far less viscous, has less silica, erupts at a higher temperature and is denser than granitic lava (properly called rhyolitic lava when it is on the surface). Basaltic lava is composed primarily of pyroxenes and calcium rich plagioclase with small amounts of olivine. Rhyolitic lava primarily contains alkali feldspars and quartz.
How do scientists determine mantles is denser than the crust?
The mantle is composed of basaltic rock, the crust is composed mostly of granitic rock. Basalt is denser than Granite.
What is the relationship in the silicon content and the viscosity of magma?
There is an inverse relationship between magma viscosity and silicon content. Lavas erupting from basaltic volcanoes (like Hawaii) have a much lower viscosity and are much hotter than those erupted by volcanoes whose magmas are rich in silicon. There may be up to 8 orders of magnitude viscosity difference between basaltic magmas (SiO2 contents or about 45 %) and rhyolitic magmas (SiO2 > 70 %).
Why do granitic felsic magmas usually crystallize before reaching earth's surface?
Felsic magma is very viscous, so if often gets "stuck" in plutons rather than erupting.
What is the thickest the continental or oceanic?
i believe the continental(granatic)crust is thicker than oceanic(basaltic)crust but i could be wrong
How is continental lithosphere different from oceanic lithosphere?
Continental plates are thicker and less dense. Continental plates are mainly granitic in composition. Oceanic plates are mainly basaltic in composition. The rock of continental plates is on average, much older than the rock of the oceanic plates. The oceanic plate underlies the oceans, and the continental plate makes up the land masses. Continental plates do not subduct at convergent plate boundaries.
