Abstract

Based on 5000 analyses of geological prospecting samples from four alunite deposits (Began’, Ukraine; Haft Sanduq, Iran; Bolshaya Kremenyukha and Kachar, Kazakhstan) and 6000 microprobe analyses of alunite, the features of changes in three parameters of alunite quartzite composition have been studied: (1) alunite content, (2) mole fraction of K in alunite, and (3) correspondence of the amount of K and Na to that of alunite sulfur. All three parameters are highly variable. A linear correlation between them has been identified in over half of the exploration workings. This correlation is sometimes very strong, approaching a functional relationship, especially for two: the alunite content and mole fraction of K in alunite. In the first three of the above-mentioned deposits, this correlation is almost always positive, and in the last, it is always negative. In other words, as alunite content increases, it becomes higher-K in the first case and higher-Na in the second case. Alunite quartzite makes up a regular zone of the infiltration metasomatic column of sulfuric acid alteration in aluminosilicate rocks under conditions apparently close to isothermal. However, the highly variable contents of the basic minerals (alunite and quartz) and alunite composition point to a difference between the alunite quartzite formation model and the theoretical model for isothermal infiltration metasomatic rock. According to the theoretical model, the solution and rock compositions mainly change at the boundaries of the metasomatic zone, whereas the rock and mineral compositions are not characterized by significant variations within the zone. During alunite quartzite formation, the solution and rock compositions change not only at the boundaries, but also within the zone due to ongoing oxidation of sulfur compounds in the solution with the sulfate formation. An increasing sulfate concentration leads to the solution becoming supersaturated in relation to alunite and causes its precipitation, with filling of voids and displacement of quartz. Cooling, heating, or a change in the composition of the hydrothermal system solutions lead to temporal variations in the K/Na ratio in precipitated alunite. Alunite formation inside the alunite zone, accompanied by changes in the mole fraction of K in deposited alunite, is the reason for the high variability of the alunite quartzite composition and for the correlation between the alunite content and its mole fraction of K. If the contribution of higher-K alunite to the variability of its total content is higher than that of higher-Na alunite, a positive correlation is likely to appear, otherwise a negative correlation is more probable.

中文翻译：

---

铝石英岩组成的变异性反映了其成因的特征

摘要

根据对4个钠铝石矿床（乌克兰Began'; Haft Sanduq，伊朗; Bolshaya Kremenyukha和Kachar，哈萨克斯坦）的地质勘探样品进行的5000次分析和6000次钠铝石的微探针分析，得出了钠铝石石英岩组成三个参数变化的特征。研究：（1）亚铝酸盐含量；（2）亚铝酸盐中钾的摩尔分数；（3）钾和钠的含量与亚铝酸盐硫含量的对应关系。所有这三个参数都是高度可变的。在超过一半的勘探工作中已经确定了它们之间的线性关系。这种相关性有时非常强，接近功能关系，尤其是对于两个方面：亚铝石含量和亚铝石中K的摩尔分数。在上述存款的前三个中，这种关联几乎总是正的，而在最后一个中，它总是负面的。换句话说，随着亚矾石含量的增加，在第一种情况下其变为较高的K，​​在第二种情况下变为较高的Na。在明显接近等温的条件下，硅铝酸盐石英岩构成了铝硅酸盐岩石中硫酸蚀变渗透渗透交代柱的规则区域。但是，基本矿物（铝矾石和石英）和铝矾石组成的含量变化很大，这表明铝矾石石英岩形成模型与等温渗透变质岩理论模型之间存在差异。根据理论模型，溶液和岩石成分主要在交代区的边界发生变化，而岩石和矿物成分在该区域内没有明显变化。在钠长石石英岩形成过程中，由于溶液中硫化合物的持续氧化并形成硫酸盐，溶液和岩石成分不仅在边界处发生变化，而且在区域内也发生变化。硫酸盐浓度的增加导致溶液相对于亚矾石变得过饱和，并导致其沉淀，空隙的填充和石英的位移。冷却，加热或热液系统溶液组成的变化会导致沉淀的亚矾石中K / Na比的时间变化。在钠矾石带内部形成的褐铁矿，伴随着沉积的钠矾石中K的摩尔分数的变化，是造成钠矾石石英岩组成高度变异以及钠矾石含量与其K摩尔分数之间相关性的原因。