Subduction Erosion Revealed by Late Mesozoic Magmatism in the Gangdese Arc, South Tibet

Abstract

AbstractSubduction of oceanic lithosphere can cause crustal growth and destruction, but whether this balancing act is common in a single fossil convergent system has been unclear. Here we report geochronologic‐geochemical‐isotopic data on Mesozoic igneous rocks in the central‐eastern Gangdese arc. Our results reveal: (a) A coupling of magmatic arc migration toward the continent interior with a marked incompatible enrichment of sub‐arc mantle magma sources; (b) numerous Late Cretaceous adakites were generated via combined partial melting of both eroded forearc crust debris and subducted oceanic crust; (c) the truncation of forearc crust and extremely short arc‐suture distance. Our work demonstrates that although there was significant vertical growth of juvenile crust throughout the Gangdese arc during the Late Mesozoic, a large amount of continental crust was returned back into the mantle through lateral subduction erosion at the same time. This study provides important insights into long‐term material recycling on Earth.