Prolonged Slab-derived Silicate and Carbonate Metasomatism of a Cratonic Mantle Wedge (Maowu Ultramafic body, China)

Abstract Mass transfer between crust and mantle at continental margins is a crucial process in shaping heterogeneity material cycling deep Earth. usually archived by the slab-derived and/or asthenosphere-derived component, which metasomatize cratonic wedge. Clarifying origin temporal sequences of these records fundamental aim yet poorly resolved. Comprehensive petrography, whole-rock mineral compositions [including platinum group elements (PGE)], zircon U–Pb ages, trace elements, Hf isotopes Maowu ultramafic body (comprising harzburgites garnet orthopyroxenites) Dabie orogen (Central China) are presented this study to decode complex metasomatic histories beneath southern North China Craton (NCC). The represents typical mantle-wedge fragment with an equilibration pressure 4·0 ± 1·0 GPa temperature 750 50 °C. have high Mg# values (up 92) Ni contents (2537–2892 ppm), low Al2O3 (0·26–0·76 wt%) CaO (0·05–0·32 contents, olivine Fo (91–93), supporting from wedge partial melting extents ~20–25 %. Garnet orthopyroxenites occurring as veins wide range (83–91), (963–2353 significant enrichment light rare earth large ion lithophile elements. They show PGE patterns similar those host harzburgites. These characteristics, combined geochemical modeling, suggest that were produced through reaction silicate melts derived crust. Three types zircons identified body. group-I ages ranging ~1927 ~465 Ma separated characterized oscillatory zones, heavy element (HREE) εHf(t) (from −24·9 +21·0), felsic inclusions (e.g. quartz plagioclase). interpreted intense silicate-melt metasomatism triggered addition crust-derived sediments (containing Proterozoic detrital zircons) into NCC This formed orthopyroxenite group-II dark cores bright rims yield 421 8 256 6 both orthopyroxenites. contain Th U 5000 ppm) display steep HREE patterns, negative Eu anomalies, positive (+0·6 +8·2). Carbonates pods or veinlets matrix features may reflect long-term pervasive oxidized carbonate fluids orthopyroxenite-veined wedge, coeval secular subduction Tethyan slab carried mainly sedimentary carbonates. group-III concordant 227 Ma. record Triassic collision Yangtze NCC. Collectively, provides geochemical, mineralogical, petrological evidence periphery prolonged fluxing various can archive history along convergent margin evolved oceanic collision.