The effect of fluorine on liquidus phase relationships in the system Qz-Ab-Or with excess water at 1 kb
The effect of fluorine on liquidus phase relationships in the system Qz-Ab-Or with excess water at 1 kb
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DOI：
10.1007/bf00371960
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发表时间：
1981-05
影响因子：
3.5
通讯作者：
D. Manning
中科院分区：
文献类型：
--
作者：
D. Manning
实验测定了Qz-Ab-Or体系的液相线相关系，其中过量水和1、2和4 wt.%在1 Kb压力下加入氟。随着氟含量的增加，石英-碱长石场边界的位置远离石英顶点。最小熔融组成的位置和最小液相线温度从无氟体系的Qz 37 Ab 34 Or 29和730° C（Tuttle和Bowen 1958）逐渐变化到含4 wt.%的体系的Qz 15 Ab 58 Or 27和630° C。添加氟。在液相线以下进行了探索性实验，实验表明，对于某些块体成分，在1 kb下，在低至550° C的温度下，可以存在由两种碱性长石、石英、熔体和蒸气组成的组合物。实验结果表明，熔体中存在的氟和铝硅酸盐复合物之间可能存在相互作用，产生氟铝（AlF 63-）复合阴离子（Manning等人，1980）。所观察到的液相线相位关系的变化与氟含量的增加表明，某些富氟花岗质岩石的组合物是一致的，通过结晶的残留熔体富含氟的岩浆分异的起源。这种残余熔体可能存在于相对较低的温度下，并可能形成花岗岩岩浆活动和相关热液活动之间的连续体的一部分。由于在岩浆阶段观察到氟对铝硅酸盐相的偏好，因此不认为氟单独的存在在残余矿化热液流体的生成中起直接作用。
Liquidus phase relationships have been determined experimentally for the system Qz-Ab-Or with excess water and 1, 2, and 4 wt.% added fluorine at 1 kb pressure. With increasing fluorine content the position of the quartz-alkali feldspar field boundary moves away from the quartz apex. The position of the minimum melting composition and the minimum liquidus temperature change progressively from Qz37Ab34Or29and 730° C for the fluorine free system (Tuttle and Bowen 1958) to Qz15Ab58Or27and 630° C for the system with 4 wt.% added fluorine. Exploratory experiments have been carried out below the liquidus, and have indicated that for certain bulk compositions an assemblage consisting of two alkali feldspars, quartz, melt and vapour can exist at temperatures as low as 550° C at 1 kb.The experimental results suggest that there may be an interaction between fluorine and aluminosilicate complexes present within the melt, to produce aluminofluoride (AlF63−) complex anions (Manning et al. 1980). The observed changes in liquidus phase relationships with increasing fluorine content indicate that the compositions of certain fluorine-rich granitic rocks are consistent with an origin by crystallisation of residual melts enriched in fluorine by magmatic differentiation. Such residual melts may exist at relatively low temperatures, and may form part of a continuum between granite magmatism and associated hydrothermal activity. Because of the observed preference of fluorine for aluminosilicate phases at the magmatic stage, the presence of fluorine alone is not considered to play a direct part in the generation of residual mineralising hydrothermal fluids.