Tectonic burial of sedimentary rocks drives the building of juvenile crust of magmatic arc

Abstract Continental arcs grow primarily by addition of mantle-derived magmas, thus forming juvenile crust, although geophysical evidence, alongside field investigation exhumed terranes, show that supracrustal rocks are common components the lower portions continental arcs. The mechanisms which metasedimentary transported to deep arc crusts and their contributions ambiguous. Here, we conduct a systematic petrological, geochronological, geochemical study pelitic migmatites within Late Cretaceous meta-gabbros from crust eastern Gangdese arc, southern Tibet. Our results were derived Carboniferous sedimentary upper have significantly enriched Sr-Nd-Hf-O isotopic compositions, underwent (95–80 Ma) high-pressure granulite-facies metamorphism partial melting at ~850 °C 15 kbar generate voluminous granitic melts. This indicates significant crustal thickening chemical differentiation during final stages subduction Neo-Tethys. We suggest into underthrusting accretion magma, deeply buried altered petrological constitution compositions assimilated mantle- crust-derived propose tectonic burial is key mechanism driving building reworking magmatic throughout most geological time.