Single grain zircon SHRIMP U-Pb chronology the geological significance of the Wudaogou rock group, Yanbian

Abstract：The single grain zircon CL images and the SHRIMP U-Pb zircon dating for the Biotite-actinolite schist of the Wudaogou Group in the east of Yanbian, yield seven sets of concordant ages and one set of discord ages for 21 zircon spots. The concordant ages are 1347.8 Ma, 844.8 Ma, 340.2～313.7 Ma（Mean=323±23Ma，MSWD = 0.23, reliability = 0.88）, 292.9～288.3 Ma（Mean=291 ±25 Ma，MSWD = 0.031, reliability=0.86),279.2～266.2 Ma（Mean=279 ±28 Ma，MSWD = 0.031,reliability=0.86）,127.4～124.2 Ma（Mean=126.5±3.7 Ma，N=5，MSWD=0.12；reliability＝0.97）and 116.1～106.3 Ma（Mean= 115 ±39 Ma，N＝2，MSWD =1.2, reliability= 0.27）,respectively;and the discord ages show that the lower and upper intercept ages are 451±120 Ma and 1811±400 Ma（MSWD = 7.2）,respectively. The results indicate that the provenance of the biotite-actinolite schist is clastic materials from Mesoproterozoic, Neoproterozoic and early Paleozoic；the sedimentary diagenesis and metamorphism of Wudaogou Group accurred in Carboniferous and lower-Permian. The wudaogou Group has been reworked two times by magmatism and alteration during the periods of 279.2～266.2 Ma and 126.5～106.3 Ma.