Geochronological and geochemical constraints on the subduction modified lithospheric origin of the early Cretaceous volcanics, in the western North Huaiyang Belt of Dabie Orogen, China

Geochronological, elemental and Sr–Nd–Hf isotopic data for intermediate acid volcanic sequences from the western North Huaiyang Belt of the Dabie Orogen, China, provide new constraints for the nature of the lithosphere and the potential involvement of the subducted Yangtze crust. These rocks are calc-alkaline andesite, trachyandesite and dacite. They were dated at 129~127 Ma and show the geochemical affinity to arc volcanics. (⁸⁷Sr/⁸⁶Sr)_i ratios and _εNd(t) values range from 0.7065 to 0.7080 and –16.9 to –13.2, respectively. Zircon in-situ _εHf(t) values range from –29.4 to –20.2 and Hf model ages from 3.03 Ga to 2.46 Ga. These volcanics might be derived from a hybridized source of NCC enriched lithosphere with the deep-recycled Yangtze continental crust. Our data, along with geological observations of the early Cretaceous igneous rocks, suggest an east–west extensional magmatic pulse at 130–120 Ma along the whole North Huaiyang Belt. From east to west, the recycled Yangtze continental crust has been decreasingly involved in the NCC enriched lithosphere in response to its Triassic northwardly deep subduction and subsequent exhumation. The lithospheric extension might induce the unrooting of previously-thickened lithosphere at early Cretaceous, resulting in the generation of the synchronous Cretaceous volcanics along the North Huaiyang Belt.