Mg-Ba-Sr-Nd isotopic evidence for a mélange origin of early Paleozoic arc magmatism

In recent years, the mélange model has been increasingly considered as an important way to transfer slab components arc sources in modern subduction zones. This differs from classic fluid/melt metasomatism that it invokes physical mixing of bulk sediment, altered oceanic crust (AOC), serpentinite, and mantle wedge at slab-mantle interface. However, due lack subducted sediment compositions, not applied any significant extent paleo-subduction The evidence for AOC serpentinite also hinders our understanding origin arc-type magmas. Here, we report Mg-Ba-Sr-Nd isotope compositions early Paleozoic Fushui mafic rocks Qinling orogen central China, trace their constrain component transfer. show typical geochemical features enriched Sr-Nd indicating likely contribution sediments. They have low Rb/Ba ratios (<0.1), most samples ?138/134Ba values ?0.38 +0.10‰, similar those sediments (?0.2 +0.1‰) but lower than MORBs (+0.03 +0.14‰), these are derived components. One sample a high +0.31‰, (up +0.4‰). is correlated with fluid input; instead, results AOC. exhibit variable ?26Mg (?0.23 ?0.11‰), slightly higher MORBs. reflects 26Mg-enriched source. Our only identify (sediment, AOC, serpentinite) source, suggest may be transferred source by process. study therefore provides solid generation magmas processes zones, which confirms role material transport.