【摘要】 广西东南部罗容杂岩体由辉长岩 -闪长岩 -二长岩 -正长岩组成 ,马山由碱性辉长岩 -正长岩 -花岗闪长岩 -花岗岩组成。它们富 K、富大离子亲石元素 (L IL ) ,无 Nb、Ta负异常等特征表明它们是形成于板内环境的钾玄质侵入岩。罗容杂岩体的各种岩石和马山的基性岩的εNd(T)高 ,为 +1.5到 +3.3,它们是交代地幔部分熔融产生的岩浆在地壳深部分异的产物。马山的花岗岩的εNd(T)稍低 ,为 - 0 .6 ,此岩石单元是由幔源岩浆加热地壳使之熔融的壳源岩浆形成的 ,并伴有与幔源岩浆的混合或交换。此二杂岩体形成于拉张构造环境。地幔物质上涌导致了中生代华南地壳张裂以及华南大规模花岗岩和相关矿床的形成。更多还原

【Abstract】 Luorong complex is composed of gabbro, diorite, monzonite and syenite, and Mashan alkaline gabbro, syenite, granodiorite and granite. They are enriched in K and LIL elements with no negative anomaly in Nb and Ta. These characteristics suggest that they belong to shoshonitic series formed in intraplate environment. All rock types in the Luorong and mafic units in the Mashan complex show high ε Nd ( T ) ranging from +1.5 to +3.3, suggesting that they were formed by fractionation of magma generated by partial melting of a metasomatized mantle in the deep crustal level. However, granite of the Mashan gives slightly lower ε Nd ( T ) -0.6, that suggests that it was formed by melting of the crust heated by the upwelling mafic magma. The near zero ε Nd ( T ) suggests an involvement of the mantle derived component by mixing or isotope exchange. The two complexes were formed in an extensional tectonic environment. The upwelling of the mantle was responsible for the extension of the crust of southeastern China, the formation of the extensive granitic magmatism and related ore deposits during the Mesozoic era.更多还原