摘要
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。
Meso- and Neoproterozoic mafic-ultramafic rocks from northern Guangxi have been dominantly classified as calcalkaline series. The mafic rocks have Nb/La-pm = 0.13similar to0.51, Th/La-pm = 0.85similar to3.3, Ti /Ti-* = 0.29similar to0.61 and show negative Nb and Ti anomalies in primitively mantle normalized patterns. The Meso-proterozoic mafic rocks share lower epsilon(Nd)(t) than those of Neoproterozoic, i.e. -1.99similar to5.13 vs. -0.74similar to2.4 respectively. They together show geochemical features of island arc volcanic series and thought to be the products of magmatism of convergent plate boundary rather than derived from mantle plume. Therefore, they be couldn't considered as a indicator of breakup of Rodinia supercontinent.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第1期9-18,共10页
Acta Petrologica Sinica
基金
国家自然科学基金(批准号49872030)资助项目成果之一
