Recycling of continental crust materials: Geochemical constraints from post-collisional alkaline intrusive rocks in the Dabie orogen

Post-collisional alkaline intrusive rocks from the Dabie orogen were studied for their whole-rock major-trace elements and Sr-Nd-Hf-Pb isotopes, as well zircon U-Pb ages Hf-O isotopes. The results provide geochemical constraints on nature of mantle sources thus insight into crust-mantle interaction in continental collision zone. are composed syenite nepheline syenite. Syn-magmatic dating by LA-ICP-MS them yielded Early Cretaceous 131.3 ± 1.4 Ma to 122.6 0.6 Ma, coeval with post-collisional magmatism orogen. One relict age 211 is consistent timing metamorphism ultrahigh-pressure (UHP) metamorphic this They have arc-like trace element distribution patterns, such enrichment LILE (large ion lithophile element) LREE (light rare earth but depletion HFSE (high field strength element), enriched Sr-Nd-Hf isotope compositions high ( 87 Sr/ 86 Sr) i ratios 0.7077–0.7131 negative ε Nd (t) values −16.0 −9.4 Hf −17.5 −12.7. Their syn-magmatic zircons three groups comparable those UHP Central-South North Dabie, which represent upper middle crust subducted South China Block, respectively. In regard, slab–mantle evident during Triassic collision. We suggest that melts derived Block reacted lithospheric wedge resulting phlogopite-bearing metasomatites, whose partial melting would generate Cretaceous.