云南哀牢山金矿带镇沅超大型造山型金矿床碳质物特征及其成矿意义  

Characteristics and metallogenic significance of carbonaceous materials in Zhenyuan super-large orogenic gold deposit in Ailaoshan gold belt,Yunnan Province,China

作　　者：武中洋 孙晓明 丁正鹏 高显青 WU ZhongYang;SUN XiaoMing;DING ZhengPeng;GAO XianQing(Guangdong Provincial Key Laboratory of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,Guangdong,China)

机构地区：[1]中山大学地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,广东珠海519082

出　　处：《矿床地质》2024年第1期43-59,共17页Mineral Deposits

基　　金：国家自然科学基金项目(编号:91855213、41972070、41672071和U1302233)资助。

摘　　要：哀牢山金矿带位于三江特提斯造山带的东南部,发育有一系列大型-超大型造山型金矿床,并广泛发育碳质物,但碳质物在金矿成矿过程中的作用还尚不明确。为了确定碳质物在金矿化过程中所扮演的角色,本研究以哀牢山金矿带镇沅超大型造山型金矿发现的不同种类的碳质物和共生黄铁矿为研究对象,对其进行了岩相学、拉曼光谱、傅里叶红外光谱、碳同位素和激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)分析,研究结果表明镇沅金矿中有3类碳质物:CM1、CM2和CM3。CM1呈深灰色不规则形态,拉曼光谱分析显示CM1具有低强度、宽的D1带和高强度、窄的G峰,D2峰较明显,计算显示其形成温度为172~200℃,低于成矿温度(250~330℃)。此外,傅里叶红外分析结果表明CM1石墨化程度低,含较少的CH键和C=O键,表明其未经历热液蚀变。碳同位素分析显示CM1样品的δ^(13)C值为-26.46‰~-26.89‰。与CM1空间上共生的黄铁矿(Py1)呈草莓状分布于碳质板岩中,LA-ICP-MS结果表明Py1的Co、Ni、Zn、Mo、Te元素含量高;CM2呈灰色细长沥青状,拉曼光谱分析显示CM2的D1峰和G峰较CM1更为尖锐,面积近似,且D2峰的光谱分峰程度很低,计算显示其形成温度为358~463℃,高于成矿温度。傅里叶红外分析结果显示,CM2石墨化程度高,在2925 cm^(-1)和1705 cm^(-1)处有明显的谱峰,含有较多的CH_(2)+CH_(3)、C=O和C=C键。CM3呈灰色细小颗粒状,拉曼光谱分析显示CM3的光谱特征与CM1的相似,但CM3的D2峰具有独立的峰段,计算显示其形成温度为258~322℃,与成矿温度一致。碳同位素分析显示CM3的δ^(13)C值为-9.09‰~-14.12‰。与CM3空间上共生的黄铁矿(Py2)呈自形分布于含金石英脉中,LA-ICP-MS结果表明Py2的As、Au元素含量高。综合以上结果,笔者认为CM1来源于有机质,形成于碳质板岩的早期成岩阶段,属于变质成因,与其共生的Py1形成于成岩期,属于沉积成因的黄铁�The Ailaoshan gold belt is located in the southeastern part of the Sanjiang Tethys orogenic belt.It consists of a series of large and super-large orogenic gold deposits.Moreover,carbonaceous materials(CM)are widely rec‐ognized in those deposits.However,the role of carbonaceous materials in the deposit formation is still unclear.In order to determine the role of carbonaceous materials in the gold mineralization,different kinds of carbonaceous materials and symbiotic pyrites found in Zhenyuan super-large orogenic gold deposit in Ailaoshan gold belt were analyzed by petrographic observation,Raman spectroscopy,Fourier Transform infrared spectroscopy,carbon iso‐tope and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)analysis.The results show that there are three types of carbonaceous materials in Zhenyuan gold deposit,namely CM1,CM2 and CM3.CM1 has a dark gray irregular shape.Raman spectroscopic analysis shows that CM1 has a low-intensity,wide D1 band and a high-intensity,narrow G peak,and D2 peak is more obvious.Calculation shows that its formation tem‐perature is 172~200℃,lower than the metallogenic temperature(250~330℃).In addition,the FTIR shows that CM1 has a low degree of graphitization,contains less CH and C=O groups,indicating that it has not undergone hydrothermal alteration.Theδ~(13)C values of CM1 samples range from-26.46‰to-26.89‰.Framboidal pyrite Py1 and CM1 are spatially associated and distributed in carbonaceous slate.The LA-ICP-MS results show that Py1 has high content of Co,Ni,Zn,Mo and Te.CM2 is gray slender asphalt.Raman spectroscopy shows that the D1 and G peaks of CM2 were sharper than CM1.The area of D1 peak and G peak of CM2 are similar,and D2peak has a low degree of spectral separation.The calculation shows that its formation temperature is 358~463℃,which is higher than the metallogenic temperature.The Fourier analysis shows that CM2 is highly graphitized,with obvious spectral peaks at 2925 cm~(-1)and 1705 cm~(-1),containing more CH_2+CH_3,C=O and C=C gr

关 键 词：造山型金矿 碳质物 拉曼光谱 镇沅金矿 哀牢山金矿带 

分 类 号：P618.51[天文地球—矿床学]