摘要
沿甘孜-理塘断裂带广泛发育有三叠纪玄武岩,该断裂带北段的玄武岩多为SiO_2大部分不饱和蚀变较强的基性岩,根据TiO_2K_2O、P_2O_5、Al_2O_3和CaO含量判定为亚碱性拉斑玄武岩系列。痕量元素特征表明,玄武岩为轻稀土弱富集型,∑REE、∑LREE/∑HREE、δEu、Eu/Sm、Sm/Nd都显示与大洋拉斑玄武岩一致。笔者认为,理塘断裂带南段在晚二叠世打开并逐步向北推进,北段于早三叠世打开,中三叠世为甘孜-理塘海发育的鼎盛时期,晚三叠世逐渐闭合。
Triassic basalt is exposed widely in Garze-Litang fracture zone. The basalt in the northern district of the said fracture zone is a stongly altered and SiO2-unsaturated basic rock which should be a member of alkali tholeiite series on the basis of contents of TiO2 K2O, P2O5, Al2O3 and CaO. Trace element geochemistry indicates that it is a LREE-slightly enriched basalt with ∑REE, ∑LREE/∑HREE,δEu, Eu/Sm,Sm/Nd similar to those of oceanic tholeiite. This paper believes the southern district of Garze-Litang fracture zone opened in Late Permian and drove gradually northwards, while the northern dis-trict opened in Early Triassic, Garze-Litang Sea was most widespreading in Middle Triassic and closed in Late Triassic.
出处
《四川地质学报》
1993年第3期201-208,共8页
Acta Geologica Sichuan
基金
国家重点金矿地质科技项目90-51-06
关键词
甘孜—理塘断裂带
蛇绿混杂岩
玄武岩地球化学特征
Garze-Litang fracture zone,ophiolitic me'lange,geochemical characteristics of basalt
