The trachytes and trachyandesites from Zhenghe County exposed in north part of Zhenghe-Dapu fault zone in Fujian Province. LA-ICP-MS zircon U-Pb dating yielded a weighted mean 206Pb/238Pb age of 101 ± 1.5 Ma（MSWD = 0.38，n = 18） for the trachyandesites. The rocks are enriched in Si, K and show peraluminous feature，with lower MgO, FeOt and CaO content. They show significant enrichment in LILEs and LREEs with LREE/HREE = 14.09 ~20.48，(La/Yb)N = 17.42 ~ 28.59，(La/Sm)N = 5.56 ~ 7.75. They also show slight negative Eu anomaly and depletion in HFSEs with marked negative Nb-Ta, P and Ti anomalies. They exhibit higher initial 87Sr/86Sr values from 0.714 17 to 0.714 47 and lower εNd(t) value of -9.0 to -8.9. In addition, the zircons from these rocks show εHf(t) values in the range of -10.67 to +2.72, with Hf model ages（TDM2）of ca. 1.84 ~ 0.99 Ga，indicating that the source materical was derived from anatexis and recycling of Mesoproterozoic and Neoproterozoic crust with different proportions of input from juvenile crust materials and mantle derived materials. All the samples plot in the area of the VAG and syn-COLG in the tectonic setting discrimination diagram，suggesting that they formed in a compressional tectonic environments. The synthesis of these data indicates that the southeastern margin of South China is not always in an extensional tectonic setting during the Cretaceous period. The tectonic setting transferred from compression to extension between Early and Late Cretaceous. The trachytes and trachyandesites are the product of the tectonic transformation and the dated age 101±1.5 Ma of the trachyandesites constrain the initial time of the extensional tectonic event. This study has important significance to reveal the intermittent compressional tectonic activity among extensional environment in the Late Mesozoic in the southeast margin of the South China.
He Jian Li Longming Ren Shenglian Lin Shoufa Li Jiahao Ge Yanpeng Feng Lamei. Geochronological，geochemical characteristics of trachyandesites from Zhenghe County in Fujian Province：Implications for the Late Mesozoic compressive-extensional tectonic events in the Southeast China[J]. Chinese Journal of Geology, 2017, 52(2): 592-615.