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4.6 How does magma generation4.6 How does magma generation
connect to plate tectonics?connect to plate tectonics?
Magma forms in areas of unique conditions in Magma forms in areas of unique conditions in the upper mantle/lower crust.the upper mantle/lower crust.
Partial melting can happen where rising mantle Partial melting can happen where rising mantle remains hot and experiences decreasingremains hot and experiences decreasing pressure such as along divergent boundariespressure such as along divergent boundaries or hot spots.or hot spots.
Partial melting can also occur by the addition of Partial melting can also occur by the addition of water by subductionwater by subduction of convergent plateof convergent plate boundaries.boundaries.
The rising of mafic The rising of mafic magma may cause partialmagma may cause partial melting of continental crust to form felsicmelting of continental crust to form felsic magma.magma. Docsity.com
compositions so diverse?compositions so diverse?
A single volcano may extrude lavas A single volcano may extrude lavas exhibiting very different compositionsexhibiting very different compositions
Bowen Bowen’’s reaction series and thes reaction series and the composition of igneous rockscomposition of igneous rocks N.L. Bowen demonstrated that as a magma N.L. Bowen demonstrated that as a magma cools, minerals crystallize in a systematiccools, minerals crystallize in a systematic fashion based on their melting pointsfashion based on their melting points
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Figure 3.
compositions so diverse?compositions so diverse?
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compositions so diverse?compositions so diverse?
Fractional crystallization: As minerals crystallize out, the remnant melt changes as compared to the original melt
Fig 4.22 Docsity.com
compositions so diverse?compositions so diverse?
Magma assimilation: as magma rises through Magma assimilation: as magma rises through surrounding rock it melts; parts are incorporatedsurrounding rock it melts; parts are incorporated into the melt.into the melt.
Magma mixing: when a new “ Magma mixing: when a new “pulsepulse”” of magmaof magma injects into an intrusive body it may mix, forminginjects into an intrusive body it may mix, forming a magma of different composition than either.a magma of different composition than either.
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compositions so diverse?compositions so diverse?
Melting rocks produces magma of differing Melting rocks produces magma of differing compositions. The extent to which the rockscompositions. The extent to which the rocks melt also determines composition.melt also determines composition.
Fractional crystallization can change a magma Fractional crystallization can change a magma into one with a different composition.into one with a different composition.
Rocks surrounding a magma chamber may Rocks surrounding a magma chamber may partly melt and become assimilated.partly melt and become assimilated.
Two or more magmas may mingle to produce a Two or more magmas may mingle to produce a hybrid magma of mixed composition.hybrid magma of mixed composition.
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4.8 Why are there different types of4.8 Why are there different types of
volcanoes and volcanic eruptions?volcanoes and volcanic eruptions?
Fig 4.24 Docsity.com
