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福建政和粗面岩和粗面安山岩出露于政和—大埔断裂带北段.LA-ICP-MS锆石U-Pb定年法测定粗面安山岩成岩年龄为101±1.5 Ma (MSWD=0.38,n=18).粗面岩和粗面安山岩主量元素具有富硅、钾和过铝质的特征,且MgO、FeOt、CaO等含量较低;岩石具有富集LILE和LREE,亏损HFSE的特征,LREE/HREE为14.09 ～ 20.48,(La/Yb)N=17.42 ～ 28.59,(La/Sm)x=5.56 ～ 7.75,并且具有Eu负异常特征(δEu=0.60～0.66).粗面岩和粗面安山岩具有较高的87Sr/86Sr初始比值(ISr=0.714 17和0.714 47)和较低的εNd(t)值,εNd(t)=-9.0～-8.9,以及变化范围大的εHf(t)值,εHf(t)=-10.67～+2.72,二阶段年龄(TDM2)为1.84～ 0.99 Ga,表明岩浆主要来源于中-新元古代地壳的重熔,并且伴有不同程度的新生地壳或幔源物质的加入.构造环境判别图解上,粗面岩和粗面安山岩所有样品均位于VAG及syn-COLG区域,表明其形成于一个挤压的构造环境,说明华南大陆东南缘在白垩纪并非一直处于伸展构造环境,而是在早晚白垩世之交存在一期由挤压向伸展的构造转换事件,本次研究的粗面岩和粗面安山岩应为这次构造转换的产物,其成岩年龄则代表一期挤压构造事件的上限年龄,它对揭示中国大陆东南缘在晚中生代伸展环境中存在间歇性挤压的构造活动有重要意义.“,”The trachytes and trachyandesites from Zhenghe County exposed in north part of ZhengheDapu fault zone in Fujian Province.LA-ICP-MS zircon U-Pb dating yielded a weighted mean 206pb/23spb 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 8TSr/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.