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红化(赤铁矿化)是热液铀矿床中最常见的一种近矿围岩蚀变,长期以来已成为普查铀矿的一种找矿标志。因此,红化蚀变一直为铀矿地质工作者所重视,对其成因曾提出了多种看法和解释。其中流行最广的一种看法认为,红化蚀变的地球化学实质在于含铀热液中的六价铀和围岩中的 Fe~(2+)发生氧化还原反应,致使六价铀还原成四价铀,形成沥青铀矿沉淀,与此同时围岩中的 Fe~(2+)却被氧化为 Fe~(3+),形成赤铁矿微粒使岩石变红。然而一系列野外地质现象和室内鉴定分析结果却与上述解释相矛盾。对其形成的物理化学条件(氧化还原电位、热力学条件)的分析和计算也表明,红化蚀变并非铁铀之间简单氧化还原反应的结果,而是一个与多种因素有关的复杂的地球化学过程。
Redness (hematite mineralization) is the most common near-uranium alteration in hydrothermal uranium deposits and has long been a prospecting indicator for uranium census. As a result, red alteration has always been valued by uranium geologists, and various opinions and explanations have been put forward on its causes. One of the most popular view is that the essence of the geochemistry of red alteration alteration is the redox reaction of hexavalent uranium in uranium hydrothermal solution with Fe2 + in the surrounding rock and the reduction of hexavalent uranium into In the meantime, Fe2 + in the surrounding rock is oxidized to Fe3 +, forming hematite particles to turn the rock red. However, a series of field geological phenomena and indoor appraisal results contradict the above explanations. Analysis and calculation of the physicochemical conditions (oxidation-reduction potential and thermodynamic conditions) formed by them also indicate that redox alteration is not the result of a simple redox reaction between iron and uranium but a complex earth with many factors Chemical process.