相山火山碎屑岩中粒间应力效应迹象

EVIDENCE ON GRAIN-TO-GRAIN STRESS EFFECT IN PYROCLASTIC ROCKS OF XIANGSHAN

利用显微粒间应力效应迹象分析方法,发现相山火山岩中广泛而强烈地发生过机械压实作用。所谓“碰撞斑晶破碎”是粒间压应力汇集的结果。因而岩石的成岩作用是在压应力场中进行,属于火山碎屑堆积的产物,应将其归属于火山凝灰岩类。该凝灰岩在成岩后又遭受热变质作用,发生明显的重结晶,使岩石目前产生了一些非标型特征。

Xiangshan volcanic rock had been named 'Lava with cracked phenocrysts' by many authors in recent years. Using the method for analysis of grain-to-grain stress effect we had found evidence on rock compaction. The so-called cracked phenocrysts may be the result of converged grain-to-grain stress effect. For this reason, the petrogensis of these rocks took place under the action of compressive stress, and the rocks were formed by the accumulation of pyroclastic debris. They can be classified to volcanic tuff. After the tuff diagenesis, they once again were subjected to thermal metamorphism and then recrystallization. Thus the rocks exhibit some untypical properties.