Building a continental arc section: Constraints from Paleozoic granulite-facies metamorphism, anatexis, and magmatism in the northern margin of the Qilian Block, northern Tibet Plateau

Abstract Continental arcs in active continental margins (especially deep-seated arc magmatism, anatexis, and metamorphism) can be extremely significant evaluating continent building processes. In this contribution, a Paleozoic section is constructed based on coeval granulite-facies metamorphism, magmatism the northern margin of Qilian Block, which record two episodes crust growth. The deeper layer lower mainly consists medium-high pressure mafic felsic granulites, with apparent peak pressure-temperature conditions 11–13 kbar 800–950 °C, corresponding to crustal depths ~35–45 km. high-pressure granulite local garnet-cumulate represent residues via dehydration melting involving breakdown amphibole anatectic garnet Zircon U-Pb geochronology indicates that these high-grade metamorphic rocks experienced metamorphism at ca. 450 Ma. upper crust, most abundant are preexisting garnet-bearing metasedimentary rocks, orthogneiss, amphibolite, medium-pressure amphibolite-facies 20–30 km These orthogneiss have also partial mica rare 457–453 shallow mid-crust primarily composed diorite-granodiorite batholiths volcanic cover multiple origin, were intruded during 500–450 Ma, recording long-term growth differentiation episode. As whole, depicted including: (a) first episode documented lithological assemblage composing mafic-intermediate intrusive derived from modified lithospheric mantle subducted oceanic southward subduction North Ocean 500–480 Ma; (b) second recorded transition initial collision 460–450