福建新生代碱性超基性火山岩地球化学特征及构造意义  

Geochemical Features of the Cenozoic Alkaline Ultramafic Volcanic Rock in Fujian and Their Tectonic Significance

作　　者：张贵山[1,2] 温汉捷[2] 胡瑞忠[2] 裘愉卓[2] 

机构地区：[1]长安大学地球科学与国土资源学院,西安710054 [2]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵阳550002

出　　处：《地质学报》2009年第2期284-294,共11页Acta Geologica Sinica

基　　金：国家重点基础研究发展计划(973项目)(编号2007CB411402);中国科学院知识创新工程项目(编号KZCX2-102;KZCX3-SW-125)资助的成果

摘　　要：为了解福建新生代地幔性质和大地构造背景,对柳城玻基辉橄岩进行系统的年代学和元素地球化学研究。岩石为碱性超基性岩,形成于12.6Ma,富Mg、Fe和贫碱性质,以富集LILE、HFSE、Nb与Ta正异常为特征,强烈富集LREE,相对亏损HREE,(La/Yb)N=35.1～36.2,δEu=0.98～1.00,微量元素特征与洋岛玄武岩(OIB)类似。微量元素地球化学特征表明,该岩石是地幔橄榄岩低度部分熔融的产物,成岩过程没有地壳混染;源区地幔具有HIMU性质,由软流圈地幔、脱水洋壳与残留岩石圈地幔混合组成,表现出富集的特征;柳城玻基辉橄岩形成于大陆裂谷环境。与新生代玄武岩进行对比研究表明,中国东南部地幔组成存在多个地幔端元成分。The paper studies the chronology and geochemistry of limburgite at Liucheng, Fujian provience, in order to better understand the Cenozoic mantle nature and the geotectonie setting of Fujian. Limburgite is a kind of alkaline ultramafic rock, and formed at 12.6Ma. It is enriched in Mg and Fe, especially LILE and HFSE, and depleted in alkali elements. Nb and Ta shows positive anomalies. The rock is also strong enrichment in LREE and relatively depletion in HREE. The all above-mentioned features of trace elements are similar to those of the ocean island basalt （OIB）. The trace elements analysis shows that limburgite is the product of partially melting of mantle peridotite and diagenesis did not undergo the crustal contamination. The source mantle shows the HIMU nature. The asthenosphere mantle, the dehydrated ocean shell and remaining the ancient enrichmental mantle had mixed to form the source. The Liucheng limburgite formed in the continental rift. Compared with the Cenozoic basalts, it is suggested that the mantle compositons of southeastern China are characterized by multiple mantle end components.

关 键 词：新生代 碱性超基性岩 地球化学 大陆裂谷 HIMU 福建 

分 类 号：P595[天文地球—地球化学]