基于多种光谱学分析技术的地质样品宏微观组构特征研究——以钦杭成矿带南段金山银金矿床岩石样品为例

摘要

The complexity of geological processes created the macroscopic and microcosmic characteristics of geological samples with inhomogenous features.These features can be revealed effective through spectroscopy analysis technology.This study took the ore and surrounding rock samples from Jinshan Ag-Au deposit of southern Qinzhou-Hangzhou metallogenic belt while carrying out macroscopic geochemical characteristic and microcosmic characteristics analysis based on the X-ray fluorescence spectroscopy,plasma mass spectrometry and Raman spectrum.The results showed that the main elements of ore and surrounding rock had great differences while the distribution patterns of trace element and rare earth element were similar.It reflected that the trace elements and rare earth elements showed high geochemical stability in the process of mineralization.Raman spectral characteristics of quarts showed that the peak at 507 cm-1 did exist in ore samples,but disappeared in surrounding rock samples.It indicated that the ore and surrounding rock went through different temperature and pressure in the ore-forming process,and the peak could be used as the signs of whether exists mineralization.Comparison with the Raman shift next to 463 cm-1 for quartz between ore and surrounding rocks,the FWHM and integral strength of fitting peak denote that the quartz in ore samples have better crystal degree than that of quartz in country rocks.These quartz microstructure changes should be subjected to the late hydrothermal activity.The quartz in the surrounding rock is influenced by the late hydrothermal,part of the ore-forming fluid may be from surrounding rock,and the ore-forming fluid has multiple phase,the crystallization degree of mineral was in different stages,causing different FWHM.%地质过程的复杂性造就了地质样品宏观和微观特征的不均一性,这些地质样品的不均一特征可以通过光谱学分析技术予以有效的揭示.研究以钦杭成矿带南段金山银金矿床的矿石与围岩样品为例,开展了基于X射线荧光光谱(XRF)和等离子体质谱(ICP-MS)分析技术的宏观地球化学特征和基于拉曼光谱(Raman)分析的微区特征分析.宏观地球化学分析结果表明,矿石与围岩的主量元素组成差别较大,但稀土元素配分模式和微量元素分布模式基本相似,这反映微量元素和稀土元素在成矿作用过程中表现出了较高的地球化学稳定性.关于石英的拉曼分析结果显示,矿石的石英存在507 cm-1附近的峰位,而围岩样品均没有出现,这应该反映了二者结晶过程中具有不同的温度和压力等条件并导致石英结构存在差异,该拉曼位移的存在与否构成了成矿过程相关地质作用的判别标志.矿石与围岩中石英463 cm-1附近拉曼位移的半高宽(FWHM)及拟合峰积分强度比对结果显示,矿石样品中石英结晶程度与有序度明显优于围岩样品中石英,这反映了成矿过程中热液活动对石英微观结构的改造.围岩中石英受后期热液影响大,部分成矿物质源于热液从围岩中带出,且成矿流体存在多期性,不同阶段矿物结晶程度不同,从而造成了特征拉曼位移FWHM值的不同.