是里特曼的组合指数确定火成岩碱度，σ= ( K2O + Na2O ) ^2 / ( SiO2 - 43 )，此类火山岩在化学成分上的特点是SiO2含量为45%~53%,K2O+Na2O含量平均为36%左右，σ值<3.3。
银山火山岩次火山岩属于高钾钙碱性系列。
Yinshan volcanic subvolcanic rocks belong to the high potassium calc alkali series.
岩相学特征表明，该火山群为典型的钙碱性系列玄武岩安山岩英安岩弧火山岩组合。
The (examination) of the petrography shows that the volcanic terrains in Tengchong are typical of the basalt - (andesite) - (dacite) arc volcanic rock associations of the calc-alkaline series.
渐新世火山岩为高钾钙碱性系列，中新世岩石属于钾玄岩系。
Eocene lavas belong to high K Calc alkaline (HK CA) series and those of Miocene to shoshonite (SHO) series.
应用推荐