Petrogenesis and tectonic implication of Late Jurassic-Early Cretaceous granitic magmatism in the Xing’an Block, NE China: Geochronological, geochemical and Hf isotopic evidence

This study presents new geochronological, whole-rock geochemical, and zircon Hf isotopic evidences for the age, petrogenesis, and source of Mesozoic granitic rocks of the Xing’an Block, NE China. These evidences reveal the Late Mesozoic tectonic evolution of the eastern section of the Central Asian Orogenic Belt. LA-ICP-MS zircon U-Pb age data indicate that the syenogranite, monzogranite, and alkali feldspar granite units, as well as their associated diorite microgranular enclaves, were emplaced between 150-142 Ma, providing evidence of Late Jurassic to Early Cretaceous magmatic events within the Xing’an Block. The granites contain high concentrations of SiO2 (65.24%–75.73 wt.%) and K2O (3.94%–5.30 wt.%), low concentrations of MgO (0.10%–1.30 wt.%), and A/CNK values of 0.92–1.06. In addition, Hf isotopic analysis of zircons from the 150–142 Ma granites yields eHf(t) values of +4.54 to +12.16 and two-stage Hf model ages from 906 to 423 Ma, indicating that they formed from magmas generated by partial melting of a juvenile Neoproterozoic–Phanerozoic accreted crustal source. The basic magma source for the diorite microgranular enclaves most likely formed from partial melting of a depleted mantle that had been metasomatized by subduction-related fluids. Combining these new geochemical data with the geology of this region, Late Jurassic to Early Cretaceous magmatism in the Xing’an Block most likely occurred in an extensional environment associated with closure of the Mongol-Okhotsk Ocean.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author