胶东曲家隐伏金矿纳米金微粒与围岩微裂隙识别

Prospecting for concealed ore deposits is an acknowledged difficulty in mineral exploration industry. In recent decades, many successful cases of deep penetration geochemistry has been achieved in prospecting for concealed ore deposits, and significant progress has been made in the study of anomalous mechanisms. Metallic nanoparticles that were directly observed by TEM in the gases, soils and ore rocks, have been proved to be homologous and formed in the endogenic mineralization. These suggest that the research on migration mechanism has achieved a qualitative leap from descriptive model to empirical model. A vertical gold anomaly was detected by deep penetration geochemistry above the Qujia concealed gold deposit in Jiaodong. Gold is chemical inertness, and only the gold nanoparticles with gas-like properties can be migrated vertically from deep orebody to earth’s surface for a long distance. In this research, the study of nanoparticles in different media and microfracture in rock will be carried out in the Qujia concealed gold deposit. Experimental samples will be systematically collected in different media to obtain the characteristics of nanoparticles and microfracture, to determine the existence form and inheritance relationship of Au nanoparticles in surface and deep media, and to establish the empirical evidence for deep penetration geochemistry of Jiaodong concealed gold deposits. The results will cement theoretical basis of deep penetration geochemistry and provide a great scientific support to prospecting for concealed ore deposits.

隐伏矿勘查一直是找矿界公认的难题。近些年来，深穿透地球化学在隐伏矿勘查和异常机理研究取得了显著进展。在地气、土壤和矿石中直接观测到纳米金属微粒，迁移机理研究从描述性模型向实证性模型实现了质的飞跃。在胶东曲家隐伏金矿上方探测到具有垂直对应的金异常，而金具有化学惰性，只有呈类气体性质的纳米形式才能长距离垂向迁移至地表。本项目以曲家金矿床为研究对象，系统采集矿石、围岩、蚀变带、断裂带、矿体上方和背景区地气及土壤样品，利用扫描电镜、透射电镜、X粉晶衍射、纳米CT等手段，研究各介质中纳米微粒以及岩石微裂隙特征，包括微粒种类（大小、形态、结构）、微粒之间的聚合特征、微粒元素含量及比值、岩石微裂隙和纳米孔大小以及贯通性等，确定纳米Au微粒在地表和深部各介质中的存在形式和继承关系，揭示胶东曲家隐伏金矿深穿透地球化学的微观实证性证据。成果将巩固深穿透地球化学的理论基础，为进一步应用于隐伏矿勘查提供科技支撑。

隐伏矿勘查一直是找矿界公认的难题，深穿透地球化学是一种通过识别地表介质中成矿元素的微弱异常信息以寻找深部隐伏矿体的地球化学勘查理论与方法。深穿透地球化学迁移理论和方法技术一直是勘查地球化学领域的前沿课题，如何证实地表圈定的深穿透地球化学异常是由深部隐伏矿体所引起一直是业内争论的焦点问题。本项目选择项目组前期已开展过深穿透地球化学探测试验且取得理想效果的胶东曲家隐伏金矿，利用扫描电镜、透射电镜、纳米CT等微观观测手段开展纳米金微粒和围岩微裂隙识别研究。结果表明：1）地表地气和土壤样品中能观测到大量纳米金属颗粒，颗粒以合金、单质或化合物形式存在，具有序晶体结构，大小从几个纳米到几百个纳米，成分以Au、Ag、Cu、Pb、Ti等元素为主，与矿种密切相关。2）矿石和断层泥样品中观测到纳微米Au颗粒以及含Au-Ag-Cu等成矿元素的纳微米颗粒。3）深穿透地球化学异常区和背景区地气与土壤样品中纳微米颗粒观测结果对比而言，异常区土壤和地气中均观测到Au、Ag、Cu、Co、Ti等含成矿元素的纳微米级颗粒，化学组成与矿种密切相关，而背景区仅观测到C、Si、O、Ca等元素纳微米级颗粒。4）胶东曲家金矿区主要岩石类型黑云二长花岗岩、英云闪长质片麻岩、变辉长岩都具有明显的微裂隙和纳米孔，且利用离子束扫描电镜在微裂隙和纳米孔中发现了纳米金和黄铁矿等矿化。观测结果证实了地表各介质中的纳微米金属颗粒与深部矿体中的纳微米金属颗粒具有继承关系，推断成矿元素纳微米颗粒不是来自周围环境，而是与深部矿体有关。提出胶东曲家金矿区深穿透地球化学异常形成机制是纳微米金属颗粒在地气流为主的多营力接续迁移的结果，揭示了胶东曲家隐伏金矿深穿透地球化学的微观实证性证据，成果进一步巩固了深穿透地球化学的理论基础，为其应用于隐伏矿勘查提供了科技支撑。