摘要
改进了K_2NboF_5·H_2O及K_2TaF_7配合物的制备方法,用快速淬火高压釜及Ar气作为压力介质,对过去实验用莫雷釜所获得结果(王玉荣等,1979;成矿实验研究组,1972)进行了重新测定。实验结果表明,随温度增高(250—550℃1×10~8Pa)、压力增大(5—15×10~7Pa550℃)K_2NbOF_5及K_2TaF_7水解作用不断增强。K_2NboF_5及K_2TaF_7水解作用仅与HF浓度有关,与NaF浓度无明显关系。本文对Nb、Ta在花岗岩熔体及流体相之间的分配实验(王玉荣,1979)进行了计算,Ta在HF介质中的分配系数的变化明显大于Nb。对成矿机理作进一步讨论。
K2NbOF5·H2O and K2TaF7 were prepared through melting Nb2O5 and Ta2O5 respectively with KHF2·2H2O and recrystallizing. The hydrolysis properties of K2NbOF5 and K2TaF7 were determined again by using a rapidly quenching vessel. As temperature (from 250 to 550℃) and pressure (from 500 to 1500 bars) increase, the degree of hydrolyses of both K2NbOF5 and K2TaF7 will increase. Nb- and Ta-fluorine complex compounds are instable in supercritical aqueous fluids. The degree of hydrolysis of both K2NbOF5 and K2TaF7 decreases with increasing concentration of HF, independent of the concentration of NaF.The distribution coefficients of Nb and Ta between granitic melt and fluid phase are less than 0.15, i. e., most of Nb and Ta are left in granitic melt. The distribution coefficient of Ta is more dependent on the concentration of HF than that of Nb. The significance of hydrolysis in Nb- and Ta-mineralization is also discussed in the present paper.
出处
《地球化学》
CAS
CSCD
北大核心
1992年第1期55-62,共8页
Geochimica
基金
国家自然科学基金
编号:4860075
