Magma Generation - Aleutian Arc (Scheland, 2015)
Item
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Title
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Magma Generation - Aleutian Arc (Scheland, 2015)
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Description
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The melts produced subduction zones are sourced by the mantle wedge between the subducting and overriding lithospheric plates (Fig. 1). Under normal conditions melts do not form in the mantle (Fig. 2). The external invigoration that creates conditions conducive for partial melting of the mantle wedge is the introduction of water as a volatile into the system.
Water lowers the melting point of the rocks and films of melt form around the crystals in the mantle wedge.
Once enough melt has formed it begins to rise to lower pressures. As it rises it may assimilate surrounding rocks if it has enough thermal energy, volatile content, and the pressure and composition conditions of those rocks permit it. Once the melt reaches a certain point in the overlying arc it stalls as it encounters the room problem. This allows for more melt for rise into the system, the melting of the surrounding rock, which may be easier than the mantle source rocks due to increased incompatible content.
The Aleutian Arc creates the staple melt of island arc settings, the calc-alkaline compositional series. This is despite the mantle source. Thus, the above mentioned evolutionary processes must have taken place to some degree. This is further investigated in the geochemistry section of this exhibit.
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Subject
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The processes that facilitate the forming of magma bodies at the convergent margin setting that is the Aleutian Arc
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Creator
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Cullen Scheland
