闽西南地区晚中生代花岗质岩石的同位素年代学、地球化学及其构造演化  

Geochronology and geochemical characteristics of late Mesozoic granotic rocks from southwestern Fujian and their tectonic evolution.

作　　者：毛建仁[1] 陈荣[1] 李寄嵎[2] 叶海敏[1] 赵希林[1] 

机构地区：[1]南京地质矿产研究所,南京市210016 [2]台湾大学地质系

出　　处：《岩石学报》2006年第6期1723-1734,共12页Acta Petrologica Sinica

基　　金：中国地质调查局科技外事部资助的基础研究项目(编号:200313000070)。

摘　　要：本文研究的闽西南地区晚中生代花岗质岩体中莒舟花岗岩体单颗粒锆石U-Pb年龄为136．0Ma,133．9Ma,黑云母Ar-^(39)Ar年龄为132．3Ma,菜刀岐石英斑岩单颗粒锆石U-Pb年龄为117．4Ma,太华花岗岩体全岩Rb-Sr年龄为114．9Ma,都属早白垩世。莒舟花岗岩富Si、K、Rb-Th,Y含量高,铝弱过饱和,贫Sr、Ba、P、Ti、Eu,过渡元素显著亏损而具壳源型花岗岩特征,菜刀岐石英斑岩是其高程度分异演化的产物,并为锡矿床的形成提供了物质基础。莒舟岩体是在岩石圈伸展的底侵作用下所形成的,岩石中有少量幔源组分加入,岩石的ε_(Nd)(t)偏低(-7．21),t_(DM)偏高(1．52Ga)。太华花岗岩体的ε_(Nd)(t)稍高(-3．60～-3．68),t_(DM)稍低(1．21Ga),岩石中有较多幔源组分加入,是壳幔混合源花岗岩。过铝质壳源型花岗岩可以在与岩石圈伸展作用相关的张性构造环境中形成,壳幔相互作用对锡矿床的形成具有重要的贡献。Late Mesozoic granitic plutons are studied in the paper. The results show the ^206Pb/^238U ages of zircon and the ^40Ar-^39Ar integrated age of biotite are 136.0Ma, 133.9Ma and 132.3Ma respectively in Juzhou granitic pluton; the ^206Pb/^238U ages of zircon in Quartz porphyry of Caidaoqi is 117.4Ma; Rb-Sr isochronal age of Taihua pluton is 114.9Ma, which were formed in Early-Cretaceous. Juzhou granitic rocks are regarded as the crust-derived type granite ,which is characterized by rich in Si,K,Rb-Th,Y , poor in Sr, Ba, P, Ti, Eu , weakly peraluminous and strongly depleted in transition elements. Quartz porphyry of Caidaoqi was derived from high degree differentiated evolution in Juzhou pluton and would provide main material foundation for tin deposit formation. Juzhou pluton with lower εNd （t） （ -7. 21 ） and higher tDM （1.52Ga） was formed by basaltic underplating under lithosphere extension environment. There was a small amount of mantle composition in the rocks. Taihua pluton with higher εNd （ t ） （ - 3.60--3.68 ） and lower tDM （1.21Ga） was considered as mixing resources granite of crust-mantle. There was a large amount of mantle composition in the rocks. Peraluminous crust-derived type granites would occur in tensile tectonic environment related to the lithosphere extension. The interaction of crust-mantle made great contributions to tin ore genesis.

关 键 词：花岗岩 年代学和地球化学 锡矿床 构造环境演化 闽西南 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]