ScienceEnvironmental SciencePlanet Earth Ch 6
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Planet Earth Ch 6

Veronica Edwards avatar Veronica Edwards
24 July 2022
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question
Igneous rocks are
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intrusive extrusive volcanic ash pyroclastic flow
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Igneous rocks are formed by magma that originates in the
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asthenosphere
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Melting that occurs due to a decrease in pressure called:
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decompression melting
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Most magmas contain
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silica
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What is not a major type of magma?
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assimilation magma
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Which of the following does not affect magma or lava viscosity
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buoyancy
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The process by which mafic minerals freeze first in a melt, leaving behind a more felsic magma is called:
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fractional crystallization
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Felsic lava with high volatile content will most likely create a
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pyroclastic flow
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What is useful in the classification of igneous rocks
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texture, density, mineral constituents, grain size
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Where are igneous rocks not typically created?
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passive continental margins
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Where is the source of heat that slows the cooling of the earth
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radioactive decay
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Identify the factors which cause melting and thus the formation of magma.
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decompression volatiles heat transfer
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Why are there so many types of magma?
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the source of rock from which they form may vary different magmas may mis to form new magma
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Why does magma rise from depth to the surface of the Earth?
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the surrounding rock creates pressure that pushes it upward it is less dense than the rocks that surround
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The change in the viscosity of a melt is directly proportional to the change
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silica content temperature
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What factors control the cooling time of magma within the crust
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volume of the intruded magma the depth at which the magma cools
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What does grain size generally indicate about the cooling of a melt?
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larger crystals indicate the melt cooled gradually