晶洞花岗岩

Miarolite

晶洞花岗岩是太姥山的成景岩石。它形成于距今约 9 千万年前，是一种特殊的来源较深（岩浆地幔成分占 65.3%~76.3%）、定位浅（深度为 1~2 千米）的花岗岩，岩石中的 SiO₂含量一般 > 76%，由于这种岩浆具有较高的粘度，在近地表处冷凝结晶过程中，所含气体无力逸出而形成空腔，在岩浆结晶的晚期进一步形成特殊的晶洞构造。

The miarolite is a major landscape-forming rock in Taimu Mountain, formed about 90 million years ago. It is a special granite with a relatively deep magma source (the mantle-magma component about 65.3%~76.3%) and shallow forming position (about 1~2 kilometers deep). The SiO₂ content is generally over 76%. Due to its high viscosity, the gases contained in the magmas were incapable to escape away in the process of condensation and crystallization near the earth’s surface, so the numerous cavities were formed in the granite. The special cavity structure would occur in the later period of the magma crystallization.