作　　者： ; (丘志力）; (冯敏）; (金春梅）; (李榴芬）;

机构地区： 中山大学地球科学与工程学院

出　　处： 《光谱学与光谱分析》 2014年第9期2397-2401,共5页

摘　　要： 水岩反应是天然低质量硬玉岩(翡翠)在风化搬运和埋藏过程中获得品质改善的重要机理,这种反应一般被认为是在低温还原条件下完成的,目前,科学界对这种低温变质水岩反应机理的了解知之甚少。利用显微红外光谱对水岩反应前后翡翠矿物集合体及晶体进行了精细原位(in-situ)测试。结果显示,水岩反应后硬玉集合体矿物组成及单晶矿物主量元素的成分均没有明显的改变,但含水量明显增大,和水岩反应前相比,硬玉单晶体结构水峰3 550cm-1向高频漂移,水岩反应前后矿物晶体边缘-晶核-边缘测点含水量也呈现规律性变化,部分样本的含水量甚至有数倍的增加。其中晶粒边缘的含水量明显大于晶粒内部含水量,和高温高压变质过程中硬玉中水含量的变化呈现相反的趋势,暗示了硬玉中的H+/OH-在高压变质反应和常压低温水岩反应过程中在硬玉内部的迁移方向及机制明显不同。这一现象的发现为了解变质反应过程中水在硬玉中的行为及翡翠质量改善机理提供了新的线索。 Weathering &transporting and depositing processes may improve the quality of some natural low-quality jadeite through reaction with surrounding water fluids.But the mechanism of such water-rock reaction has not been known clearly to date.Applying microscopic Fourier transform infrared spectroscopy(Micro-FTIR),this paper carried out comparatively in-situ research of jadeites' mineral composition before and after water-rock reaction.The results show that water-rock reaction cannot impact jadeites in their major and minor element composition,but greatly change their water content.Jadeites became richer,with even several times increase,in water content,after experiencing water-rock reaction,and hence show a shift of absorption peak at 3 550cm-1 to higher frequency.The mineral crystals of these jadeites showed reglar variation in water content from core to edge,and these jadeites have more water in marginal area than in center area,being opposite to the change in water content in jadeite during high temperature and pressure metamorphic process,hence implying that there are different mechanism and shift direction for H+/OH-of jadeite between high pressure metamorphic process and low temperature water-rock reaction.We think that this finding may contribute to understanding the behavior of water in jadeite during metamorphic process and the mechanism of jadeite quality improvement.

关 键 词： 水岩反应 翡翠 硬玉岩 显微红外光谱 结构水

领　　域： [机械工程—光学工程] [理学—光学] [理学—物理]