闽西南地区中生代花岗闪长质岩石的同位素年代学、地球化学及其构造演化  

Geochronology and geochemical characteristics in Mesozoic granodioritic rocks in southwestern Fujian,and their tectonic evolution

作　　者：毛建仁[1] 许乃政[1] 胡青[1] 李寄嵎[2] 谢芳贵[1] 

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

出　　处：《吉林大学学报（地球科学版）》2004年第1期12-20,共9页Journal of Jilin University：Earth Science Edition

基　　金：国土资源部"九五"科技专项基金资助项目(地科专96-02);中国地质调查局基础地质调查项目(19991020110003)

摘　　要：闽西南地区存在两期中生代花岗闪长质岩石。早、晚两期花岗闪长质岩石分别以汤泉和四方岩体为代表,其形成年龄分别为183～157Ma和108～105Ma。汤泉和四方岩体都为A/CNK<1.0的准铝质花岗岩类,均属板内钙碱型岩石。汤泉岩体因富Na2O、Ba、Sr,贫HREE、Y、Yb有别于四方岩体而具高SrBa低Y的埃达克质岩石特征,是地幔起源的基性岩浆底侵作用,促使加厚的元古代下地壳基性岩部分熔融所形成;四方岩体是地幔起源的基性岩浆与中下地壳物质部分熔融形成的花岗质岩浆混合作用的结果。汤泉岩体的形成指示研究区自中侏罗世(180Ma)以来已有岩石圈伸展的岩石学记录,随时间推移,岩石圈伸展减薄作用愈加强烈,壳幔作用愈加明显,越至晚期岩石中地幔组分含量越高。Two stages of the Mesozoic granodioritics occurring in southwestern Fujian, whose ages are 183～157 Ma and 108～105 Ma respectively,are represented by Tangquan and Sifang plutons. Both Tangquan and Sifang plutons are regarded as the metaluminous granites with A/CNK<1.0 and belonged to cal-alkaline series of intraplate. As Tangquan pluton is enriched in (Na2O),Sr,Ba and depleted in HREE, Y, Yb, it is different from Sifang pluton in the geochemical characteristics of high SrBa lower Y adakite-like granites. Tangquan pluton was formed by partial melts of raising thick lower-crust derived basic rock corresponding to Proterozoic, resulting from the underplating of mantle-derived basic magma. Sifang pluton was mixed between granite magmas of middle-lower crust-derived by partial melting and mantle derived basic magma. The forming of Tangquan pluton is indicated that there have been the petrological records of lithosphere extension since Middle-Jurassic (180 Ma) in the region, with the time past, the lithosphere extension and thinning is intense and the interaction of crust-mantle is obvious. The contents of mantle composition in igneous rocks are increased gradually with the time.

关 键 词：花岗闪长岩 中生代 构造演化 阑西南地区 地球化学 同位素年代学 

分 类 号：P588.12[天文地球—岩石学]