摘要
This paper presents LA-ICPMS zircon U-Pb geochronology and Hf isotopic composition for two migmatitic and gneissic samples from the Taoxi Complex at the Aocun-Tianyuan areas (Wuping). Zircons from the two samples (FJ-137 and FJ-138) yield the weighted mean 206Pb/238U ages of (496±4)Ma (n=8) and (494±6)Ma (n=17), respectively. Some grains give Neoproterozoic ages (641~657 Ma and 799 Ma), which can be considered to be inherited grains. The Hf isotopic compositions for FJ-137 sample range from -2.3 to -18.2 with the Hf model age of 1.84~2.65 Ga. The results show that: 1) the Mesoproterozoic Taoxi “Group” is most likely to be the Complex; 2) these rocks probably represent the products of the reworked Neoproterozoic-Early Paleozoic sedimentary sequences; and 3) the 494~496 Ma magmatism in the Wuping area might be correlated with the Yu’nanian orogenic event that were previously discussed in other studies.