what does metamorphic rock turn into at subduction zones
Subduction zone metamorphism Paired metamorphic belts are a set of parallel metamorphic rock units parallel to a subduction zone displaying two contrasting metamorphic conditions and thus two distinctive mineral assemblages. Nearest the trench is a zone of low temperature, high pressure metamorphic conditions characterized by blueschist to eclogite facies assemblages. This assemblage is associated with subduction along the trench and low heat flow. Nearest the arc is a zone of high temperature-low pressure metamorphic conditions characterized by amphibolite to granulite facies mineral assemblages such as aluminosilicates, cordierite, and orthopyroxenes. This assemblage is associated with high heat flow generated by melting beneath the volcanic arc.[20]