Neoproterozoic adakitic rocks from Mopanshan in the western Yangtze Craton: Partial melts of a thickened lower crust

摘要: Abstract The tectonic setting of South China during the Neoproterozoic remains a subject debate. adakites from Xuelongbao and Datian along western margin Yangtze Craton have been used to argue for an arc assuming that these rocks are melting products subducted oceanic slab (Zhou, M.F., Yan, D.P., Wang, C.L., Qi, L., Kennedy, A., 2006a. Subduction-related origin 750 Ma adakitic complex (Sichuan Province, China): Implications giant magmatic event in China. Earth Planetary Science Letters 248, 286–300.; Zhao, J.H., Zhou, 2007. Adakitic Plutons Arc Magmatism Western Margin Block, Journal Geology 115, 675–689.). However, slab-related petrogenetic model is unsuitable (782 ± 6 Ma) Mopanshan. Mopanshan characterized by low MgO, Cr Ni contents, high Rb/Sr Sr/Y ratios negative eNd(t) values (− 2.06 − 0.43). These features, plus presence relict zircons (1.16–0.83 Ga) Mesoproterozoic zircon Hf ages (1.06–1.27 Ga), inconsistent with slab-melting origin, but favour thickened continental lower crust. It likely crust associated magma generation may experienced continuous growth reworking since Sibao Orogeny. Sharing main geochemical features rocks, also derived This interpretation casts doubts on proposed south Instead, represent intra-continental extensional setting.