Geochronology, geochemical characteristics, and geological implications of the Guangnan pluton in the Middle Segment of the Zhuguangshan batholith, South China

The Guangnan pluton is located on the central of South China and the junction of Hunan and Jiangxi provinces. The zircon U–Pb age dating results show that the pluton formed between 164 and 148 Ma. The pluton composed of biotite granite, two-mica granite, and garnet-bearing granite, which contain higher SiO2 (72.82–76.16wt.%), lower Zr (83.5–118 μg/g), and ASI > 1. These geochemical characteristics are very similar to high-silicon peraluminous light-colored granite or ferroan calc-alkaline high-silica granite, or muscovite-containing peraluminous granite (MPG) type. The zircon εHf(t) value (− 3.94– − 11.67) and those of inherited zircon characteristics indicate that multiple melting of lower crustal materials, which were formed in the Caledonian, Indosinian, and Early Jurassic periods, acted as part of the source rock of the mid-late Jurassic Guangnan high-silica granite in the Zhuguangshan area. This study shows that the high-silica granite in Guangnan area is the production of the post-collision stage of the collision between Western Pacific ancient land and the South China orogenic belt in Early Yanshanian. In the “post-collision” stage during the Middle Jurassic, the magmatic material was formed by partially melting and multiple remelting of the lower crustal metamorphic argillaceous rock and/or metamorphic acidic igneous rock because of the heat from the base-invasion basic magma.