摘要
“磐龙玉”是一种产于吉林省磐石市小红石砬子铅锌矿矿床的矿化蚀变带围岩中的石英质玉石,主要由石英和绢云母组成,多呈黄绿色。本文基于野外调查,采用常规宝石学测试、X射线粉晶衍射、红外光谱、激光拉曼光谱、紫外-可见光反射光谱、电子探针、全岩主量元素分析、全岩稀土与微量元素分析及锆石U-Pb定年等多种方法,对“磐龙玉”的宝石学特征、光谱学特征和地球化学特征进行系统研究,探讨其颜色形成机理、成矿时代及矿床成因机制。结果表明,“磐龙玉”原岩主要为流纹质凝灰岩,经硅化、绢云母化等蚀变作用使其颜色、粒度发生显著变化而达到玉石的标准。其绿色色调的致色离子为Fe^(2+),Fe^(2+)的类质同象混入使得绢云母呈绿色,绢云母含量与“磐龙玉”绿色呈正相关;而Fe^(3+)的存在则使其呈现黄色(针铁矿)和红色(赤铁矿)色调。“磐龙玉”形成于中-低温变质环境,锆石U-Pb定年结果(228.1±0.7)Ma表明其形成与该区中生代晚三叠世的酸性岩浆侵入活动关系密切,其成矿过程主要发生在气水热液期,可划分为硅化、绢云母化和碳酸盐化三个阶段。
“Panlong Jade”,a type of quartzite jade,is derived from the mineralized rocks surrounding the Xiaohongshilazi lead-zinc deposit in Panshi City,Jilin Province.Mostly yellow-green,it is primarily composed of quartz and sericite minerals.Based on field investigations,this study systematically examines the gemological,spectroscopic and geochemical characteristics of“Panlong Jade”using conventional gemological testing,X-ray powder diffraction,infrared spectroscopy,laser Raman spectroscopy,whole rock geochemical principal component analysis,electron probe,ultraviolet-visible reflection spectroscopy,whole-rock rare earth and trace element analysis and zircon U-Pb dating,while exploring the color formation mechanism,age and ore genesis of“Panlong Jade”.The results indicate that the protolith of“Panlong Jade”is mainly rhyolite tuff,and its color and particle size change due to alteration processes such as silicification and sericitization to meet jade standards.The green coloration is due to the presence of Fe^(2+),which is isomorphic substituted in sericite,giving it a green hue.There is a positive correlation between the sericite content and the green color of“Panlong Jade”.On the other hand,the presence of Fe^(3+)imparts yellow(goethite)and red(hematite)hues.“Panlong Jade”formed in a medium to low-temperature metamorphic environment.Zircon U-Pb dating results(228.1±0.7)Ma suggest that the formation of“Panlong Jade”is closely related to acidic magmatic intrusion activity during the Late Triassic period of the Mesozoic era.The mineralization process of“Panlong Jade”can be divided into three main stages:silicification,sericitization,and carbonation.
作者
杨宇婷
白峰
温宇航
张启东
张道元
王雯
YANG Yuting;BAI Feng;WEN Yuhang;ZHANG Qidong;ZHANG Daoyuan;WANG Wen(School of Gemmology,China University of Geosciences(Beijing),Beijing 100083,China;Jilin Sanhe Mining Exploiting Co.,Ltd,Changchun,Jilin 130000,China)
出处
《现代地质》
北大核心
2025年第1期167-182,共16页
Geoscience
基金
吉林省磐龙玉分类与质量评价研究科研项目(77932020019)。
