论文部分内容阅读
桂北中、新元古代镁铁质-超镁铁质岩主要属钙碱质岩系,镁铁质岩的Nb/La_(pm)=0.13～0.51,Th/La_(pm)=0.85～3.3,Ti/Ti=0.29～0.61,在原始地幔标准化曲线上出现明显的Nb、Ti负异常,中元古代镁铁质岩ε_(Nd)(t)值低(=-1.99～-5.13),新元古代镁铁质岩ε_(Nd)(t)值相对较高(=-0.74～2.4),它们都具有岛弧火山岩系的地球化学特征,是会聚板块边缘岩浆作用的产物,不具有地幔柱来源的岩浆的特性,不能作为Rodinia超大陆裂解的标志。
The Neoproterozoic mafic-ultramafic rocks in northern Guangxi are mainly calc-alkaline rock series with Nb / La_ (pm) = 0.13 ~ 0.51 and Th / La_ (pm) = 0.85 ~ 3.3 , Ti / Ti = 0.29-0.61, obvious Nb and Ti anomalies appeared on the normalized mantle normalization curve, and the value of ε_ (Nd) (t) of the Mesoproterozoic mafic rocks was low (= -1.99-5.13) The Proterozoic mafic rocks have relatively high ε_ (Nd) (t) values (= -0.74 ~ 2.4), all of which have the geochemical characteristics of island arc volcanic rocks and are the product of marginal magmatism in the convergent plate. They do not have the mantle plume The origin of the magma can not be used as a sign of the supercontinent in the Rodinia.