机构地区: 华侨大学环境科学与工程系
出 处: 《矿物学报》 2002年第4期335-342,共8页
摘 要: 周潭群斜长角闪岩的基本组成矿物是斜长石和角闪石 ,不同样品中还可以出现黑云母、石英和碱性长石等。所有斜长角闪岩显示石英拉斑系列特征 ,其稀土元素配分曲线呈平坦型 ,显示轻微的轻稀土亏损和Eu亏损 ,与由岛弧及洋拉斑玄武岩形成的斜长角闪岩的稀土分布型式及稀土特征一致。根据微量元素蛛网图的斜率和Nb、Zr异常情况以及低的Zr/Nb比值、V Ti、Y Cr、Zr Ti Sr、Zr Y相关性 ,认为斜长角闪岩之原岩为岛弧型玄武岩 ,周潭群的原岩形成于岛弧环境。元素地球化学和Nd同位素特征指示它们的母岩浆起源于亏损程度低的地幔或来源于亏损地幔的岩浆受到地壳物质的混染。 The basic assemblage of amphibolites consists of amphibole and plagioclase. Other phases include biotite, quartz and alkali feldspar. All amphibolites show the characteristics of the tholeiitic series. The amphibolites are all quartz-normative. Relatively flat REE patterns, slight depletion in LREE and Eu , resembling those of the N-type MORB and low-K tholeiitic rocks in oceanic arc and back-arc basin settings. Nb and Zr anomalies, the slope of the incompatible element distribution patterns and the Zr/Nb value, the correlations between Vi and Ti, Y and Cr, Zr and Ti-Sr, Zr and Y show island arc signatures, indicating a tectonic setting of island arc .The basaltic magma was derived from a slightly depleted mantle source with minor crustal contamination.