Research on kinetics in water-rock system and mechanism of enrichment and dispersion of elements

本研究的主要成果归纳如下。（1）人工海水与火山岩（玄武岩、英安岩）反应的热液实验表明，最终热液的化学成分（Ca、Ba、Sr）取决于热液蚀变的强度和热液的化学成分。根据这些结果可以解释重晶石、石膏和硬石膏的成因。（2）通过对热液矿区蚀变岩的大量分析结果，可以阐明热液蚀变岩中元素的地球化学行为。稀土元素含量与氧同位素组成和钾含量之间存在相关性，表明稀土元素含量是一个有用的地球化学找矿指标。（3）根据降水动力学-流体流动模型，阐明了黑矿区石英、重晶石和硬石膏的分布规律。（4）阐明了风化过程中元素迁移的机理。结果表明，吸附和离子交换是控制贱金属和稀土元素行为的重要因素。

Main results of this research are summarized as follows.(1)Hydrothermal experiments on the reaction between artificial seawater and volcanic rocks (basalt, dacite) indicate that the chemical compositions of final hydrothermal solution (Ca,Ba,Sr) depend on degree of intensity of hydrothermal alteration and chemical composition of hydrothermal solution. The genesis of barite, gypsum and anhydrite can be interpreted in terms of these results.(2)Geochemical behavior of elements in hydrothermal alteration can be clarified based on many analytical results of altered rocks in hydrothermal mining districts. The correlation between rare earth element contents, oxygen isotopic compositions and K content was found. This indicates that REE content is useful geochemical exploration index.(3)Distribution of quartz, barite and anhydrite in Kuroko mining area was clarified and interpreted in terms of precipitation kinetics-fluid flow model.(4)Elemental migration mechanism in weathering process was elucidated. It was found that adsorption and ionic exchange are important factors controlling the behavior of base metals and rare earth elements.