The pressure estimated by amphibole geobarometer in syenite and granil

在0.05 ~ 0.34GPa的水压力和氧逸化的FMQ缓冲液条件下，对含角闪石的正长岩和花岗质岩石在600 ~ 930ºC范围内的压力进行了估算。角闪孔稳定极限曲线的P-T斜率由低压时的正斜率变为高压时的负斜率，并在两个压力点与正长岩和花岗岩固体相交。我们认为大和山脉正长岩中的角闪洞可能是在小于0.3GPa（深度：-10 km）的压力下结晶的，可能是在浅层地壳岩浆室中。Hammarstrom和Zen（1986, 1992）提出了钙碱性岩体的结晶压力与镁闪锌矿总铝含量之间的经验相关性。然而，在本实验中，固体附近角闪洞的化学成分没有变化。我们报道了角闪洞中寄生虫含量随温度升高而升高。如果与不同温度合成的角闪石相比较，角闪石地压具有相当大的不确定性。我们尝试在角闪石和辉石之间分配Na、Al、Mg和Fe。

We attempt to estimate the pressure of amphibole-bearing syenites and granitic rocks in the range 600ﾟC -930ﾟC under a water pressure from 0.05GPa to 0.34GPa and oxygen fugacitied of the FMQ buffer. The stability limit curve of amphibole changes its P-T slope from positive at low pressure to negative at high pressure, and it intersects with a solidus of syenite and granite at two pressure points. We suggest that amphibole in syenite from the Yamato Mountains could have crystallized at pressres less than 0.3GPa (depth : -10 km), probably in a shallow crustal magma chamber.Hammarstrom and Zen (1986, 1992) proposed an empirical correlation between the estimated pressures of crystallization of calc-alkaline plutons and the total Al content of horublende. However, in the present experiments, the chemical composition of amphibole near solidus does not change. We reported that the pargasite content in amphibole increases with increasing temperature. If we compared with amphiboles synthesized at different temperatures, amphibole geobarometer is considerable uncertainty. We attempt the partitioning of Na, Al, Mg and Fe between amphibole and pyroxene.