Three Stages Of Arc Migration In The Carboniferous-Triassic In Northern Qiangtang, Central Tibet, China: Ridge Subduction And Asynchronous Slab Rollback Of The Jinsha Paleotethys

Carboniferous-Triassic magmatism in northern Qiangtang, central Tibet, China, played a key role in the evolution of the Ti-betan Plateau yet remains a subject of intense debate. New geochronological and geochemi-cal data from adakitic, Nb-enriched, and normal arc magmatic rocks, integrated with results from previous studies, enable us to determine the Carboniferous-Triassic (312–205 Ma), arc-related, plutonic-volcanic rocks in northern Qiangtang. Spatial-temporal re-lationships reveal three periods of younging including southward (312–252 Ma), rapid northward (249–237 Ma), and normal north-ward (234–205 Ma) migrations that corre-spond to distinct slab geodynamic processes including continentward slab shallowing,rapid trenchward slab rollback, and normal trenchward rollback of the Jinsha Paleote-thys rather than the Longmuco-Shuanghu Paleotethys, respectively. Moreover, varying degrees of coexistence of adakites/High-Mg andesites (HMAs)/Nb-enriched basalt-an-desites (NEBs) and intraplate basalts in the above-mentioned stages is consistent with the magmatic effects of slab window triggered by ridge subduction, which probably started since the Late Carboniferous and continued into the Late Triassic. The Carboniferous-Triassic multiple magmatic migrations and ridge-subduction scenarios provide new in-sight into the geodynamic processes of the Jinsha Paleotethys and the growth mecha-nism of the Tibetan Plateau