琼西抱板群变质基性火山岩的地球化学特征及其大地构造意义  

GEOCHEMICAL CHARACTERISTICS OF METAMORPHIC BASIC VOLCANICS FROM THE BAOBAN GROUP,WESTERN HAINAN AND ITS TECTONIC IMPLICATIONS

作　　者：许德如[1] 梁新权[1] 唐红峰[1] 

机构地区：[1]中国科学院长沙大地构造研究所,湖南长沙410013

出　　处：《大地构造与成矿学》2000年第4期303-313,共11页Geotectonica et Metallogenia

基　　金：中国科学院知识创新工程项目!(KZCX2 - 113);云南省省院省校科技合作项目!(YK980 0 8)

摘　　要：海南岛抱板群变质基性火山岩的岩石学、地球化学、Sr、Nd、Pb同位素及其形成的大地构造环境的综合研究表明 ,抱板群变质基性火山岩具有洋中脊型拉斑玄武岩和岛弧型拉斑玄武岩的双重特征 ,起源于亏损地幔 ,是古俯冲消减带上部岩石圈地幔楔、自消减带卷入地幔楔地壳物质及俯冲洋壳析出的流体构成的三元混合物部分熔融结果 ,产生于扩张弧后 (或弧间 )盆地环境。地球动力学分析表明 ,古中元古代时 ,海南岛西部可能经历了一次由“开”向“合”转变的构造演化史。The different characteristics of petrology, geochemistry, Sr, Nd isotope and tectonic setting of metamorphic basic volcanics from the Baoban Group on western Hainan have been studied. The results indicated that metamorphic basic volcanics from the Baoban Group is a kind of transitional basalt, their geochemical characteristics are similar to those of arc tholeiites and MORBS with low depleted mantle origination, that the magma storeroom is the result of partial melting of three component mixture made up of melting magma caused by mantle wedge located over old diving depleted belt, melting magma of crust material being involved into mantle wedge from depleted belt and fluid being separated out from diving oceanic crust, and that their tectonic setting is a back arc or inter arc spreading basin. Geodynamic analysis shows that the tectonic evolution history from “spreading” state into “closing” state might have happened in Paleo Mesoproterozoic age on western Hainan.

关 键 词：地球化学 大地构造环境 变质基性火山岩 成因 

分 类 号：P588.3[天文地球—岩石学] P595[天文地球—地质学]