An Experimental Study of the Stability Relations, Na-K Exchange, and Isotope Exchange Properties of Jarosite at 200oC and Above

在这项研究中，将进行实验，以确定黄钾铁矾土和钠镁铁矾石稳定场的位置作为共存水相中H_2SO_4-K_2SO_4和H_2SO_4-Na_2SO_4浓度的函数。实验温度将从200摄氏度到黄钾铁矾土和钠铁矾土的稳定上限，预计将低于450摄氏度。此外，还将测量钠和钾在黄钾铁矾水溶液和硫酸盐水溶液之间的分配，黄钾铁矾土羟基中心和水之间的D分馏，以及黄钾铁矾土羟基和硫酸盐中心与水之间的18O分馏。这些实验将在压力为500巴的标准冷封热液容器中进行，是正在进行的明矾石到铁-铁轴承系统的工作的延伸。它们应该会提高我们解释酸-硫酸盐蚀变同位素数据的能力，酸-硫酸盐蚀变通常包括明矾石和黄钾铁矾土。此外，它们将有助于限制较低温度下黄钾铁矾矿的化学和同位素体系，从而补充正在进行的25摄氏度黄钾铁矾土研究。更好地了解黄钾铁矾土在地表条件下的性质，将对研究酸性矿山废水以及解释黄铁矿矿床的自然风化和氧化作用具有重要意义。

In this study, experiments will be conducted to determine the position of the jarosite and natrojarosite stability fields as functions of the H2SO4-K2SO4 and H2SO4-Na2SO4 Concentration in the coexisting aqueous phase. Experimental Temperatures will range from 200oC to the upper stability limit of jarosite and natrojarosite, which is expected to be below 450oC. In addition, the partitioning of sodium and potassium between jarosite and aqueous sulfate solutions, the D fractionation between the hydroxyl sites of jarosite and water, and 18O fractionation between the jarosite hydroxyl and sulfate sites and water will be measured. These experiments, which will be conducted in standard cold-seal hydrothermal vessels at a pressure of 500 bars, are an extension of work in progress on alunite to a ferric-iron bearing system. They should improve our ability to interpret isotope data on acid-sulfate alteration, which frequently includes both alunite and jarosite. In addition, they will help to constrain the chemical and isotope systematics of jarosite at lower temperatures, and thus complement ongoing studies of jarosite at 25oC. A better understanding of the properties of jarosite at surficial conditions will be important in the study of acid-mine drainage, and also in the interpretation of natural weathering and oxidation of pyritic ore deposits.