Heterogeneous slab components impart diverse oxygen isotope of arc magmas in northwestern circum-Rodinia subduction system

Oxygen isotopic diversity of arc magmas can be used to trace their distinct sources and, in turn, shed light on material recycling during crust-mantle interaction in the subduction zone. Herein, we present new zircon O isotopes for the Neoproterozoic (ca. 820–760 Ma) mafic to felsic igneous rocks in the western Yangtze Block (South China) to understand how slab subduction imparts diverse oxygen isotope in arc magmatic rocks from the northwestern circum-Rodinia subduction system. The ca. 807–802 Ma high zircon-δ18O basaltic andesites to dacites display variable zircon εHf(t) (−0.37–+11.5) and high δ18O values (up to 7.09 ‰). In combination with highly variable MgO (2.01–9.06 wt%), K2O (2.43–4.70 wt%), Rb/Y (2.99–8.98), Th/Ce (0.15–0.31), Th/Sm (1.51–3.21), Th/La (0.30–0.64) and Th/Yb (3.20–10.1) as well as negative εNd(t) (−4.22 to −0.86) values, these basaltic andesites to dacites originated from a mantle wedge source metasomatized by subducted fluids and sediment melts. The ca. 820–760 Ma low zircon-δ18O rhyolites and granites have elevated silicic contents (73.05–78.49 wt%), positive-dominantly εNd(t) (−0.69 to +1.99) and highly positive εHf(t) (+6.16∼+11.9) values as well as sub-mantle to mantle-like δ18O values (3.82 ‰–5.58 ‰), which were formed by the partial melting of juvenile mafic arc lower crust that was originally supplemented by mantle wedge melts metasomatized by hydrothermally altered oceanic crust (AOC) melts. The heterogeneous zircon δ18O values of igneous rocks, combined with available paleomagnetic data, indicate that the persistent peripheral subduction around Rodinia has introduced distinct metasomatized agents (i.e., subducted fluids, sediment melts, and AOC melts) into the sub-arc mantle source, which resulted in the mantle wedge heterogeneity and zircon δ18O diversity of Neoproterozoic arc magmatism across the western Yangtze Block (South China) in northwestern circum-Rodinia subduction system. Slab subduction is thus significant for the geochemical diversification of arc magmas and mass exchange between the mantle and crust.