Report on 3.4 Ga SHRIMP Zircon Age from the Yuntaishan Geopark in Jiaozuo, Henan Province

摘要

Using the reported new U-Pb age with the Sensitive High-Resolution Ion Microprobe (SHRIMP II), zircon U-Pb ages were obtained from two samples of K-feldspar felsic paragneiss and K-feldspar gneissoid trondhjemite on the southern margin of the Taihang Mountains in the North China Craton. The protolith of the K-feldspar felsic paragneiss is argillaceous-sandy clastic sedimentary rock, probably deposited in the Neoarchean. Most of the detritus zircons show heavy loss of Pb. Five spots of zircons near the upper point, yield a weighted mean ~(207)Pb/~(206)Pb age of 3399+ -8 Ma, representing an age of the sedimentary source. Two groups of zircons from the K-feldspar gneissoid trondhjemite give weighted mean ~(207)Pb/~(206)Pb ages of 2511+ -13 Ma and 2735+ -16 Ma respectively. The former represents the emplacement time of the pluton, while the latter is interpreted as the age of the inherited zircons. The new data support that the Archean geological body in the central zone has an affinity with those from the eastern block of the North China Craton.