鲁西峄山花岗岩中粗大钾长石斑晶成因探讨

Origin Study on Porphyritic Crystals in Coarse Feldspar of Yishan Granites in Western Shandong

摘要:

在鲁西地区新太古代晚期(五台期)峄山花岗岩的黑石查和望子山花岗质岩体的岩石中,钾长石粗大斑晶内有自形程度较高的斜长石等矿物包裹体沿其环带定向排列。根据野外观察及岩石、矿物学特征测试分析,钾长石斑晶属于岩浆结晶形成的原生斑晶,受化学成分及侵位结晶过程中的物理化学条件影响,钾长石的生长速度大于其成核密度,因而形成粗大斑晶。估算岩浆温度>950℃,钾长石斑晶快速生长时岩浆温度为750℃,过冷度ΔT≈150℃,基质结晶时岩浆温度为600℃,ΔT≈300℃。

Abstract:

Main Porphyritic-like Texture Rock of Yishan superunit belongs to Heishicha unit and Wangzishan unit, the potash feldspar porphyritic is bulky , high self-shape plagioclase crystalloids and other mineral crystalloids arrayed along the zone of the feldspar porphyritic. According to field survey and analysis on lithofacies, porphyritic crystals of feldspar belong to primary crystals formed by magma crystallization. Effected by chemical composition and physical and chemical condition during intrusion and cryst...