Zircon U-Pb ages for Wulian granites in northwest Sulu and their tectonic implications

The Wulian complex occurring in the north- western part of the Sulu orogen consists of metaigneous and metasedimentary rocks at greenschist-facies. Zircon U-Pb dating for three granite intrusions within it yields concor-dant ages of (672±4), (742±9) and (747±14) Ma, respec-tively. These ages indicate that the granites are the Neopro-terozoic intrusions in the northern margin of the Yangtze plate, and correspond to the magmatic complex at Luzhen-guan in the eastern part of the Beihuaiyang belt in the Dabie orogen. They were tectonic slices scraped off from the Yang-tze plate during Triassic subduction and thus belong to a part of the accretionary wedge of the Yangtze plate subduc-tion. The discovery of extensive Neoproterozoic magmatic rocks in the Wulian area suggests that the suture location between the North China and the Yangtze plates lies north of the Wulian complex.