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恰什坎萨依花岗闪长岩虽然经历了强烈的片麻岩化作用,但其铝饱和指数(A/CNK)为0.81~0.99,Na2O/K2O>1,TiO2<1.0%,轻稀土富集,分馏程度高,重稀土富集程度较低,分馏系数小,Eu弱负异常或无异常,微量元素Ba,Ti为负异常及在微量元素构造环境判别图解上样品点落在岛弧型花岗岩区等都展示出岛弧型花岗岩的典型特征.阴极发光图像反映锆石内部存在清晰的韵律生长纹,无残留锆石晶核和新生长的环边结构,U,Th含量分别变化于574~870和279~556μg/g之间,Th/U值在0.52~0.68之间,显示出岩浆锆石性质.锆石SHRIMPU-Pb定年结果为481.5±5.3Ma,代表花岗闪长岩侵位时代,与北祁连岛弧火山岩带的形成时代一致,证实了该区存在早古生代岛弧岩浆活动.
Despite its strong gneissification, the Qasshikaisai granodiorite has an aluminum saturation index (A / CNK) of 0.81-0.99, a Na2O / K2O> 1, a TiO2 <1.0%, a light rare earth rich Low concentration of heavy rare earth elements, small fractional distillation fraction, weak Eu anomalies or no anomalies, trace elements Ba and Ti are negative anomalies, and in the trace element tectonic environment, Granite show typical features of island arc granite.The cathodoluminescence images reflect the existence of clear rhythmic growth pattern inside the zircon without residual zircon nuclei and new growth ring edge structure, U, Th content were changed in 574 ~ 870 and 279 ~ 556 μg / g, and the Th / U value ranged from 0.52 to 0.68, indicating that the zircon SHRIMPU-Pb dating was 481.5 ± 5.3Ma, representing the emplacement of granodiorite Era, consistent with the formation of the arc volcanic belt in the North Qilian Island, confirming the existence of Early Paleozoic island arc magmatism in this area.