英语语法分析

Welded tuff is commonly rhyolitic in composition.

焊接凝灰岩在组成上通常为流纹岩。

The volcanics are commonly andesitic in composition, but basaltic and rhyolitic volcanics are abundant in some areas.

火山岩的组成通常是安山岩，但在某些地区玄武岩质和流纹岩质也很丰富。

Nanliang complex is mainly composed of porphyritic granite, granophyre, rhyolite - porphyry and rhyolitic agmatite-lava.

南梁岩体主要由斑状花岗岩、流纹斑岩、花斑岩及流纹质角砾熔岩组成。