柴北缘布赫特山一带滩间山群火山岩岩石地球化学特征及构造环境分析

Geochemical Characteristics And Tectonic Environment Of Volcanic Rocks Of Tanjianshan Group In Buhete Mountain Area,Northern Qaidam Basin

柴北缘布赫特山一带滩间山群的火山岩以钙碱性为主,少量具有拉斑玄武岩趋势,岩性以安山岩为主;主量元素具有低Ti的特点(TiO_(2)平均值<1%);稀土元素以轻稀土富集,具有明显的Eu负异常为特征;在微量元素蛛网图上,样品显示大离子亲石元素富集,亏损高场强元素,Nb、Ta呈现明显的“槽”。显示其形成于岛弧环境。

The volcanic rocks of the Tanjianshan Group in the Buhete Mountain area in the northern margin of Qaidam Basin are mainly calc alkaline,with a small amount of tholeiitic trend,and the lithology is mainly andesite;The main element has the characteristic of low Ti(with an average value of TiO_(2) less than 1%);Rare earth elements are enriched with light rare earth elements,characterized by significant negative Eu anomalies;On the spider web diagram of trace elements,the sample shows enrichment of large ion lithophile elements,loss of high field strength elements,and obvious"grooves"in Nb and Ta.It shows that it was formed in an island arc environment.