香花岭花岗岩稀土元素演化

香花岭地区花岗岩中的稀土元素呈逆向演化 ,其演化过程受花岗岩体系中的岩浆主成分、熔体结构相及流体组分变化等影响。花岗岩造岩矿物中稀土元素与各自岩石变化的一致性 ,可能暗示稀土元素的演化受岩浆的制约 ;稀土元素总量随岩浆演化而下降 ,与岩浆体系降温矿物的晶出、熔体相的相对减少、流体相的增加及射气分异作用的发生等有关 ,而轻稀土富集则是由于岩浆体系向碱性增强方向演化的结果。对于连续演化的花岗岩而言 ,稀土元素的分布样式或许可作为岩浆演化酸碱环境的指向 ;负铕异常的减小除与岩浆主成分的变化有关外 ,还与氧化 还原环境的变化有关

Evolution of rare earth elements of granitoid in Xianghualing area, Hunan

The evolution of granitic REE in Xianghualing area shows converse characteristics,and was affected by the change of dominant component, magmatic melt structure and fluids within magmatic system. The REE characteristics in main rock-forming minerals is consistent with each rock's, which may implies that REE evolution in granites was controlled by the dominant components. With the magma evolution, REE gross decline was related to the minerals crystal, melt phase reducing, fluids increasing, and the emanation-differentiation occurring within the magma system, but enrichment of light REE was the result of magmatic system evolved towards alkalinity increase. For continuous evolution granite, the REE pattern of granites can take as a guide for judging alkalinity-acidity environment of magmatic evolution. Besides the change of magmatic dominant components, negative europium anomaly descends is also related to the change of oxidation-deoxidizing circumstance.