Which phenomenon strongly mediates the magma composition produced during oceanic plate subduction under a continent?

💡 Explanation

When an oceanic plate subducts, melting occurs within the mantle wedge; the resulting magma rises through the overlying continental crust, undergoing crustal assimilation and fractional crystallization that significantly modify its composition because elements melt/crystallize at different temperatures/pressures. Therefore, crustal assimilation and fractional crystallization strongly alters melt composition, rather than plume interaction, slab alteration, or sediment compaction, which influence different aspects of the subduction process.

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