Emplacing Age of the Tiewadian Pluton in the South Qinling Tectonic Belt and Its Geological Implications

Tiewadian pluton is located in the contact borders between Hanyin, Shiquan and Ziyang countries in the South Qinling Tectonic Belt (SQTB), Shaanxi Province, and consists chiefly of diorite, quartz diorite, quartz monzodiorite, quartz monzonite and monzogranite. LA-ICP-MS zircon U-Pb isotopic dating reveals three magmatic emplacement stages: early stage quartz monzonite emplaced at 742±5 Ma, middle stage quartz diorite, quartz monzodiorite and monzogranite at ~722 Ma, late stage quartz diorite at 704±4 Ma. The Tiewadian pluton shows comparable lithological assemblage, emplacing ages and geochemical features with felsic rocks of Hannan complex in the north margin of Yangtze Craton, indicating that they experienced similar magmatic and tectonic evolution in the similar geodynamic background, and that the Tiewadian pluton is an important geological record relating to the Neoproterozoic subduction in the SQTB.