Biotite granodiorite age of Jiuling complex in Jiangxi Province and its limitation on the collision and splicing time of the Yangtze and Cathay plates

In order to explore the magmatic origin and tectonic setting of the Jiuling pluton in northern Jiangxi, a combined study of geochronology, geochemistry and zircon Lu-Hf isotope was carried out for the Dahutang biotite granodiorite. LA-ICP-MS zircon U-Pb dating of biotite granodiorite suggests it was formed at (835.6±1.5) Ma. Geochemistry analysis shows it belongs to the series of potassium-high potassium calcium alkaline peraluminous granite. It has the typical characteristics of S-type granite and it was derived from the melting of the Neoproterozoic Shuangqiaoshan Group. The positive zircon ε_Hf (t) value (2.8-8.2) suggests that the magma forming the granite was originated from the recycling of Proterozoic crustal material. The Dahutang biotite granodiorite was formed in a tectonic background of transition stage from syn-collision to post-collision. Combining with previous studies, it is inferred that that the upper time limit of collision between the Yangtze and Cathaysia plate should be about 835 Ma.