Tectonic Setting Comparison (kojaian, Sanders, Isihara)
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Title
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Tectonic Setting Comparison (kojaian, Sanders, Isihara)
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Description
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The tectonic settings for MORBs, OIBs and Convergent Margins are all very different. Magma that creates MORBs comes from the upper mantle. Since the upper mantle underneath a divergent boundary is responsible for producing so much magma, it is depleted in incompatible elements. Since MORBs are depleted in incompatible elements they are tholiitic. OIBs on the other hand, are created by mantle plumes that are sourced from the core-mantle boundary. Since the rocks at the core-mantle boundary are undepleted in incompatible elements, OIBs are rich in incompatible elements. This makes them rich in alkaline elements such as Na2O and K2O. Island arcs from convergent margins originate from subduction zones. As the slab subducts, water from hydrated minerals escapes from mineral structures. The water enters the surrounding mantle and lowers the melting temperature. Melt is then created and rises to the crust. Eventually this melt is erupted from the surface and forms volcanoes.
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Creator
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Claire Kojaian
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Mediator
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Tamara Carley
carleyt@lafayette.edu
