I-type granite

geology

Also known as: I-type granitoid

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In granite
These result in I-type granitoids, derived from igneous protoliths and containing moderate amounts of Al₂O₃ and high amounts of Na₂O, and S-type granitoids, derived from sedimentary protoliths and containing high amounts of Al₂O₃ and relatively low amounts of Na₂O. Amphibole and pyroxene are more common in I-type granitoids,…
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In igneous rock: Convergent plate boundaries
…chemical signatures; it is called I-type granite. The other type, called S-type granite, has muscovite and biotite and is depleted in sodium but enriched in aluminum such that corundum occurs in the norm and isotopic signatures. This suggests that such granites were formed by partial fusion of sedimentary rocks.
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