摘要
基于褐帘石热处理实验获得其分解反应:CaCeFe^(2+)Al_2Si_3O_(12)OH+5/12O_2=CaAl_2Si_3O_8+1/3Fe_3O_4+SiO_2+CeO_2+1/2H_2O(g)应用于广东新丰稀土花岗岩的计算表明,在一般讨论的花岗岩浆温度(600—800℃),水压(1—4kbar)的条件下,褐帘石稳定存在的氧逸度条件与磁铁矿接近,明显高于黑云母及NiO-Ni缓冲曲线。在探讨花岗岩岩浆氧逸度及其稀土元素行为时,褐帘石可作为很好的指示剂。
Based upon the heat decomposition reaction of allanite. CaCeFe^(+2)Al_2Si_3O_(12)OH+5/12O_2=CaAl_2Si_2O_8+1/3Fe_3O_4+SiO_2+CeO_2+1/2H_2O(g) thermodynamic calculations are carried out in this paper for the stability fO_2 of allanite. The application of above mentioned method to Xinfeng rare earth granite in Guangdong Province indicates that under the conditions of PH_2O=1—4kbars, T=600—800℃, the stability fO_2 of allanite is simmilar to that of magnetite and increases with PH_2O. This suggests that allanite was formed under relatively high fO_2 as the early crystallization phase in the magma, and thus, reflects that the light rare earth elements in the magma are precipitated under relatively high fO_2 at the early stage. It is considered by the author that allanite can be used as a useful indicator for the fO_2 condition of granite, especially for that of LREE-rich granite.
出处
《矿物岩石》
CAS
CSCD
1989年第3期26-32,共7页
Mineralogy and Petrology
