The discovery of Paleozoic leucogranite in eastern segment of Chinese Middle Tianshan and its tectonic implications

The tectonic setting and geologic evolution of the Middle Tianshan is still a controversial issue. We firstly report a garnet and tourmaline-bearing leucogranite which intruded in metapelitic rocks in the eastern segment of the Middle Tianshan, to the south of Dikaner area. SHRIMP U-Pb dating of zircons from the leucogranite yields a minimum intrusion age of 354 +/- 16Ma, while the zircons also contain some 600 similar to 1200Ma inherited components. The discovery of the leucogranite and its emplacement age indicate that the Middle Tianshan during the period from the Early Paleozoic to the early stage of Late Paleozoic was related to a setting of continental marginal arc and the collision must predate 354Ma.