Petrogenesis and Tectonic Implications of the Early Neoproterozoic Gneissic Granite in the Fuhuling Area, Western Guangdong Province

The South China Block is one of the major continental blocks in China. The formation and tectonic evolution history of the South China Block, especially the Early Neoproterozoic tectonic attributes of the Cathaysia Block are still controversial. Therefore, the Fuhuling gneissic granite in the western Guangdong province, the southeastern margin of the Yunkai Domain of the Cathaysia Block, is selected to investigate the Early Neoproterozoic evolution of the Cathaysia Block through detailed fieldwork, petrographic, zircon U-Pb geochronological and Lu-Hf isotopic, and whole-rock geochemical analyses. The gneissic granite samples exhibit weak schistosity texture developed at the edge after late deformation, and elongated biotite is orientated locally. The zircon U-Pb ages of the samples are 986–982 Ma. Their SiO2 and K2O contents are 67.70%–77.38% and 1.59%–4.50%, respectively, with A/CNK of 1.13–1.76. They have high Rb/Sr and low Al2O3/TiO2 ratios, showing features of calc-alkaline series and peraluminized S-type granites. The gneissic granties are enriched in LILEs, but depleted in HFSEs (Nb, Ta, Ti), exhibiting obvious REE fractionated patterns with significant negative Eu anomalies. The εNd(t) and εHf(t) values of the rock samples range from −7.4 to −5.4 and −8.7 to −1.5, respectively, and corresponding two stage model ages of 2.2–2.1 Ga and 2.4–1.9 Ga, respectively. These characteristics indicate that the gneissic granites were derived from partial melting of the Paleo-Mesoproterozoic metaigneous and metasedimentary rocks in the Cathaysian basement. Compared with the contemporary magmatic activities in the Wuyi-Nanling-Yunkai region, it is further presumed that the gneissic granites were formed by partial melting of the basic metaigneous and metasedimentary rocks triggered by the subduction in the southeastern margin of Yunkai Domain of the Cathaysia Block during the Early Neoproterozoic. © 2022 Science Press. All rights reserved.