Identifying deep recycled carbonates through Miocene basalts in the Maguan area, SE Tibetan Plateau

Cenozoic mantle-derived magmas are widespread on the Tibetan Plateau, and provide evidence for evolution of deep mantle its influence Plateau development. Miocene basalts in Maguan area southeastern have high MgO (9.13–13.10 wt%) Mg# (0.60–0.70) with Ce/Pb (10.6–32.5) Nb/U (43.7–52.9) ratios, similar to those oceanic basalts. Distinct from Eocene-Oligocene potassic Western Yunnan basic volcanic rocks Tengchong, these characterized by large ion lithophile elements (LILEs) concentrations, positive anomaly field strength (HFSEs) depleted SrNd isotopes, consistent melt an asthenospheric origin. The Nb/Y (1.80–2.68) ratios together low Ba/Y Ba/Th indicate a significant input slab-derived into source. Besides, Hf/Hf* Ti/Ti* significantly lower than ocean island basalt (OIB), which proportional lighter δ26Mg (-0.6‰ -0.4‰) values. Based results experimental petrology, SrMg isotope mixing model suggests that beneath had undergone metasomatism recycled carbonates prior late Miocene. above petrological geochemical understanding, geophysical data, allows us propose is most probably associated Neo-Tethys seafloor subduction, further testified decoupling between isotopes elevated LILE concentrations.