地质学报2018，Vol.92Issue(3)：520-530,11.
东天山博格达造山带东段七角井组枕状玄武岩地球化学特征及构造背景探讨
Geochemistry of the Qijiaojing Formation Pillow Basalt in the Eastern Bogda Orogenic Belt, East Tianshan and Its Implications for Tectonic Setting
摘要
Abstract
The study carried out geochemical analysis of pillow basalts in the group of Qijiaojing,Eastern Bogda Orogenic Belt in East Tianshan.The results show that the basalt belongs to sub-alkaline tholeiitic basalts,with slight enrichment in LREE ((La/Yb)N =1.89～2.21) and a weak Eu anomaly (δEu=0.89～0.96),presenting the typical features of island-arc basalts which have negative anomalies of Nb,Ta and Ti.The trace elements of pillow basalts,except active elements (Cs,Rb and Ba),are similar to that of lower crust,between one time to two times contrast N-MORB.(La/Nb)N=1.82～2.62＞＞1 suggests that the volcanic rocks was contaminated by the lithosphere during the uprising process of magma.Zr content (＞142×10-6) and Zr/Y ratio (＞4) show the characters of intraplate volcanic rocks.In multiple environment discrimination diagrams,the samples of the volcanic rocks fall into the N-MORB area or the margin of IAT area or the intraplate basalt area,presenting characteristics of both N-MORB and IAT.Combined with the sedimentary tectonic environment of early-Carboniferous strata in the region,it can be concluded that the southern Xialaoba area in the Eastern Bogda Orogenic Belt should be in the extension tectonic environment (arc-back extension) in the Carboniferous.关键词
博格达地区/枕状玄武岩/地球化学特征/沉积构造特征/构造环境Key words
Bogda region/pillow basalts/geochemical characteristics/sedimentary tectonic characteristics/tectonic environment引用本文复制引用
孙吉明,白建科,朱小辉,牛峥,马中平..东天山博格达造山带东段七角井组枕状玄武岩地球化学特征及构造背景探讨[J].地质学报,2018,92(3):520-530,11.基金项目
本文为国家自然科学青年基金项目(编号41502061、41402051)、中国地质调查局基础性公益性地质矿产调查项目(编号DD20160009)资助成果. （编号41502061、41402051）
