Zircon LA-ICP-MS U-Pb age of plagiogranite from Tonghuashan ophiolite in Southern Tianshan Mountains and its geological implications

Abstract：In Southern Tianshan Mountains of the Tonghuashan ophiolitic tectonic belt, the plagiogranite is exposed at the top of ultrabasic rocks, showing fault contact relationship. The concordant age of (406.5±5.0)Ma was obtained for the plagiogranite by the zircon micro-domain LA-ICP-MS rare earth elements analysis and U-Pb age dating，indicating that the intrusive epoch of plagiogranite was Early Devonian, and that this age represents the lower limit age of the Tonghuashan ophiolitic formation.