摘要
在13.5—38.0kbar压力下,对福建闽清碱性玄武岩进行了高压熔融曲线的测定和干、湿两种体系的熔融-结晶实验。根据实验结果,讨论了压力以及水的加入对于玄武岩熔体的晶出温度、晶出矿物的种类、矿物化学成分、自形程度的影响。还对玄武岩中巨晶矿物的形成条件做了探讨。
A series of melting-crystallization experiments on the alkali basalt samples from Mingqing, Fujian Province was carried out in dry and water-bearing systems at high pressures. A high-pressuremelting curve of the basalt was obtained. The experimental results indicate that clino-pyroxene crystallized from basalt melt at 13.5-23.7 kbar, spinal at 23.7-28.6 kbar and garnet at > 28.6 kbar. With increasing pressure, the CaSiO3 contents of clinopyroxenes increase and the FeSiO3 contents decrease, but the chemical compositions of garnet do not show any significant difference. The minerals are larger in size and euhedral in form in the water-bearing, system. Therefore, we consider that natural megacrysts of the basalt can crystallize from the water-bearing basalt magma at high pressure. So the megacrysts may be derived from the upper mantle as a result of magmatic crystallization-fractionation under high pressure
出处
《地球化学》
CAS
CSCD
北大核心
1990年第3期249-255,共7页
Geochimica
基金
国家自然科学基金
