Intraoceanic back-arc magma diversity: Insights from a relic of the Proto-Tethys oceanic lithosphere in the western Qilian Orogen, NW China

Abstract The Qilian orogeny formed by subduction of the proto-Tethyan ocean along the northern margin of Gondwana. In this paper we report geochemical, zircon U-Pb-Hf, and mapping data of the Duoruonuoer volcanic rocks from the western Qilian Orogen. Based on distinct geochemical compositions, four melt types can be distinguished: boninite-like basalt, OIB-like basalt, MORB, and high-K to shoshonitic volcanic rocks (HKSV). Field relationships show a compositional change from HKSV, MORB, OIB to boninite-like basalt, from north to south. The boninite-like basalt is low to medium-K calc-alkaline, with low TiO2 (0.13–0.18