Zircon U-Pb Ages of Volcanic and Sedimentary Rocks of the Wudang Group in the Qinling Orogenic Belt within Western Henan Province

Metamorphosed sedimentary-volcanic sequences of the Wudang Group widely distributed in the South Qinling Block are considered to be basement rocks of the Wudang Terrain and important rock units in the eastern part of the Qinling Orogenic Belt.Nevertheless,there exists controversy over the formation age of the Wudang Group.To determine the formation time of the Wudang Group,the authors reported zircon U-Pb ages obtained by the LA-ICP-MS technique in this paper.The samples were composed of a meta-sedimentary rock sample collected from the Yangping Formation in the upper part of the Group,and four meta-volcanic rock samples from the Shuangtai Formation in the lower part of the Group.Dating results demonstrate that sedimentary sources of the Yangping Formation originated mainly from Neoproterozoic(～860～640 Ma)and Paleoproterozoic(～2260～1800 Ma),and subordinately from Late Archean and Mesoproterozoic crustal materials,with an affinity to the Yangtze Block.Sedimentation should have occurred later than 640 Ma.Metamorphosed felsic volcanic rocks were formed between ～730 Ma and ～780 Ma,with the peak at(755±6)Ma,being simultaneous with the metamorphosed Neoproterozoic mafic volcanic rocks of the Shuangtai Formation within the Wudang Terrain and probably related to the breakup of the supercontinent Rodinia in petrogenesis.