此类火山岩的岩石化学特征与辉长岩 玄武岩类似，SiO2 45%~52%,FeO、MgO、CaO含量较高，属基性岩类。碱含量稍高，K2O+Na2O>4%,可达9%,里特曼指数σ=3?3~9。
山西吕梁群流纹岩是一个古元古代的弱碱性火山岩。
The rhyolites in the Upper Luliang Group of Shanxi Province of China are Palaeoproterozoic A-type volcanic rocks.
矿化与晚侏罗到早白垩世区域伸展作用期间的亚碱性火山岩关系密切。
Mineralization is closely related to subalkaline volcanism during regional extension from late Jurassic to early Cretaceous.
相对主体拉斑玄武岩，东川碱性火山岩贫ree特别是LREE，推测源区发生过先期熔融事件。
Compared with the dominant tholeiites the alkaline volcanics from Dongchuan district are less enriched in LREE, probably resulting from earlier melting events in their source.
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