英安岩 (Dacite)是一种中酸性喷出岩，属火山岩，相当于花岗闪长岩的喷出物。在中国，主要产于东南沿海各地。
定年结果表明，变质英安岩中锆石具有两组年龄。
The dating of these zircons indicates that they can be divided into two groups according to their ages.
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.
另外，研究者发现这里的岩浆的成分是英安岩而不是构成夏威夷主体的玄武岩。英安岩是花岗岩的前身。
In addition, researchers found that the magma is made of dacite, a type of rock that's a precursor to granite.
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