Which change occurs during subduction when hydrated oceanic crust descends into the mantle?

💡 Explanation

When hydrated oceanic crust subducts, metamorphic dehydration occurs because increased pressure and temperature forces water out of the crustal minerals, lowering the mantle's melting point and causing partial melting. Therefore mantle melting results, rather than thickening, divergence, or reactivation, which need different geological processes.

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