桂北宝坛地区满洞铜镍硫化物矿床铂族元素地球化学特征及其对矿床成因的制约  

PGE Geochemical Characteristics of Mandong Cu-Ni Sulfide Deposit in Baotan Area of the Northern Guangxi, China and Their Constraints on Deposit Genesis

作　　者：彭永新 马收先[2] PENG Yong-xin;MA Shou-xian(Guangdong Jinyan Industry Group Co.,Ltd.,Meizhou 514021,Guangdong,China;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]广东金雁工业集团有限公司,广东梅州514021 [2]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《地球科学与环境学报》2021年第4期674-685,共12页Journal of Earth Sciences and Environment

基　　金：中国地质调查局地质调查项目(DD20190814,DD20201173)。

摘　　要：桂北宝坛地区铜镍硫化物矿床块状矿石和浸染状矿石之间的成因联系尚存争议,对其开展研究为提高该地区铜镍硫化物矿床成因认识和下一步深部找矿勘探都具有重要意义。通过分析满洞铜镍硫化物矿床矿石和赋矿岩石铂族元素(PGE)特征,探讨桂北宝坛地区铜镍硫化物矿床成因。结果表明:满洞铜镍硫化物矿床矿石和赋矿岩石铂族元素总含量普遍较低,且与硫化物含量成明显正相关关系,铂族元素相对于Ni和Cu明显亏损;不同种类矿石和岩石原始地幔标准化铂族元素蛛网图总体表现为弱分异,Pd/Ir值为0.93~15.41;然而其相对Pt含量明显不同,块状矿石呈现强烈Pt亏损,浸染状矿石Pt呈弱富集,赋矿岩石无Pt异常;矿石和岩石Cu/Pd值((10.38~1 830.00)×10^(3))均远大于原始地幔(6 500),表明该矿床深部存在早期硫化物熔离作用,造成岩浆在浅部再次硫化物熔离时亏损铂族元素;含铂矿物在单硫化物固溶体结晶之前从硫化物熔体中直接结晶,之后硫化物熔体在构造作用下沿裂隙迁移固结形成块状矿石,从而造成块状矿石Pt亏损。The genetic relationship of massive and disseminated ores of Cu-Ni sulfide deposits in Baotan area of the northern Guangxi is highly debated, which is of great significance for acknowledgement of the genesis of Cu-Ni sulfide deposits and mineral exploration in the future. The characteristics of platinum group elements(PGE) of ores and barren rocks from Cu-Ni sulfide deposits were analyzed to constrain the genesis of Mandong Cu-Ni sulfide deposit in Baotan area. The results show that total contents of PGE of the disseminated and massive ores as well as barren rocks are quite low and well positively correlated with the content of sulfide, the PGE are significantly depleted relative to Cu and Ni;the primitive mantle-normalized PGE spider diagram of ores and barren rocks is weakly differentiated with variable Pt contents, and the ratios of Pd/Ir are 0.93-15.41;the massive ore shows a negative Pt pattern, while the disseminated ore has a bit positive Pt anomaly, and the barren rocks have no anomaly;the ratios of Cu/Pd of ores and barren rocks range from 10.38×10^(3) to 1 830.00×10^(3), much higher than that of primitive mantle(6 500), implying the occurrence of sulfide segregation in the deep of Mandong Cu-Ni sulfide deposit, which results in PGE depletion of the newly formed ores and barren rocks in the shallow intrusions;minerals rich in Pt directly crystallize from the sulfide melt prior to monosulfide solid solution(MSS) crystallization, and then the sulfide melts migrate away from the minerals rich in Pt along structural fractures and form the massive ores, which result in Pt depletion of the massive ores.

关 键 词：矿床成因 铜镍硫化物 铂族元素 硫化物熔离 块状矿石 成矿模式 新元古代 广西 

分 类 号：P611[天文地球—矿床学]