大兴安岭中南段扎木钦铅锌银多金属矿床成矿物质来源及矿床成因:来自S、Pb同位素的制约  

The sources of ore-forming materials and genesis of the Zhamuqin Pb-ZnAg polymetallic deposit in the middle-southern segment of Da Hinggan Mountains:Constraints from S,Pb isotope geochemistry

作　　者：何鹏[1] 郭硕 张天福 苏航 付启龙 HEPeng;GUOShuo;ZHANGTianFu;SUHang;FUQiLong(Tianjin Geological Survey Center,China Geological Survey,Tianjin 300170,China;Qiqihar Branch,Heilongjiang Institute of Geological Survey,Haerbin 150036,China;Institute of Geological Survey of Inner Mongolia Autonomous Region,Huhhot 010020,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]黑龙江省地质调查研究总院齐齐哈尔分院,哈尔滨150036 [3]内蒙古自治区地质调查院,呼和浩特010020

出　　处：《岩石学报》2018年第12期3597-3610,共14页Acta Petrologica Sinica

基　　金：中国地质调查局项目(DD20160041)资助

摘　　要：扎木钦铅锌银矿床位于内蒙古科尔沁右翼中旗,是近些年来在大兴安岭中南段地区新发现的一处大型多金属矿床。扎木钦矿床矿体主要呈脉状、透镜状、层状、似层状赋存于白音高老组中酸性火山岩中;根据矿石的结构、构造以及矿物之间的共生组合、穿切关系,划分出毒砂-黄铁矿阶段、铅锌金属硫化物阶段、银矿物阶段、石英-碳酸盐阶段四个主要成矿阶段。在对矿床成矿地质条件详细总结研究的基础上,为探讨扎木钦多金属矿床成矿物质来源及矿床成因,本文对矿床中主要金属硫化物开展了S、Pb同位素组成分析。硫同位素测试结果表明扎木钦矿床中δ^(34)S值为4. 4‰～5. 8‰,平均值为5. 05‰,数值均一,变化范围小,具有塔式分布特征,指示硫来源于深源岩浆。铅同位素测试结果为:^(206)Pb/^(204)Pb值为17. 761～18. 291,平均值为18. 130;^(207)Pb/^(204)Pb值为15. 509～15. 671,平均值为15. 593;^(208)Pb/^(204)Pb值为37. 800～38. 205,平均值为38. 032,上述结果显示其铅同位素组成稳定。μ值为9. 30～9. 69,ω值变化范围为34. 57～38. 15。各项分析数据及图解指示铅具有壳幔混合来源特征。扎木钦矿床硫铅同位素组成与大兴安岭地区成矿物质为岩浆来源的金属矿床特征极为相似,矿床成矿与早白垩世火山岩浆活动关系密切,是深部岩浆流体逐步演化的产物,矿床成因类型为陆相火山热液型铅锌银多金属矿床。The Zhamuqin Pb-Zn-Ag deposit,located in Horqin Right Wing Middle Banner,Inner Mongolia,is a large polymetallic deposit discovered in recent years in the middle and southern segment of Da Hinggan Mountains. The ore-hosting strata of the deposit contain a suite of intermediate-felsic volcanic lava intercalated with volcaniclastic rocks of Baiyingaolao Group,and its orebodies generally occurr as veins,lenticulars,stratiform or stratoid. According to its ore structure,symbiosis and cross cutting relationship,four stages of hydrothermal mineralization were identified in this deposit,namely,the arsenopyrite-pyrite stage,the lead-zinc metal sulfide stage,the silver mineral stage and the quartz-carbonate stage,respectively. Based on detailed studies upon the ore forming geological conditions of the Zhamuqin deposit,we analyzed S and Pb isotopic composition characteristics of metal sulfides in this deposit with the purpose to discuss its ore-forming materials and genesis of ore deposits. The results of sulfur isotope analysis show that the δ34 S of polymetallic ore values vary within a range from 4. 4‰ to 5. 8‰ with an average of 5. 05‰ and possess a tower-shaped distribution characteristics,indicating that the sulfur isotope of the deposit is derived from deep source magma. The results of lead isotope analysis show that the ratios of lead isotopes of206 Pb/204 Pb,207 Pb/204 Pb and208 Pb/204 Pb in sulfides vary within ranges from17. 761 to 18. 291( 18. 130 on average),15. 509 to 15. 671( 15. 593 on average),and 37. 800 to 38. 205( 38. 032 on average),respectively,displaying a relatively stable distribution. The μ values vary from 9. 3 to 9. 41,while the ω values vary from 34. 57 to38. 15. The analysis data indicate that the lead was mainly derived from the mixture of crust mantle materials. The sulfur and lead isotopic compositions of the Zhamuqin deposit are very similar to the metallic ore deposits with deep magma sources in Da Hinggan Mountains. The geological features of the Zhamuqin deposit show that the mi

关 键 词：同位素 成矿物质来源 矿床成因 铅锌银多金属矿床 大兴安岭中南段 

分 类 号：P611[天文地球—矿床学] P618.42[天文地球—地质学] P618.43