volcanoes are located parallel to the subduction zone in relation to a subduction zone.
where are volcanoes located in relation to a subduction zone?
parallel to the subduction zone
paired metamorphic belts were envisaged as 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.
subduction zone metamorphism
bullet::::- flat-slab subduction (subducting angle less than 30°) occurs when subducting lithosphere, called a slab, subducts nearly horizontally. the relatively flat slab can extend for hundreds of kilometers. that is abnormal, as the dense slab typically sinks at a much steeper angle directly at the subduction zone. because subduction of slabs to depth is necessary to drive subduction zone volcanism (through the destabilization and dewatering of minerals and the resultant flux melting of the mantle wedge), flat-slab subduction can be invoked to explain volcanic gaps. flat-slab subduction is ongoing beneath part of the andes causing segmentation of the andean volcanic belt into four zones. the flat-slab subduction in northern peru and norte chico region of chile is believed to be the result of the subduction of two buoyant aseismic ridges, the nazca ridge and the juan fernández ridge respectively. around taitao peninsula flat-slab subduction is attributed to the subduction of the chile rise, a spreading ridge. the laramide orogeny in the rocky mountains of united states is attributed to flat-slab subduction. then, a broad volcanic gap appeared at the southwestern margin of north america, and deformation occurred much farther inland; it was during this time that the basement-cored mountain ranges of colorado, utah, wyoming, south dakota, and new mexico came into being. the most massive subduction zone earthquakes, so-called "megaquakes", have been found to occur in flat-slab subduction zones.
subduction