大兴安岭南段白音查干Sn多金属矿床成因:矿床地质特征及Sr-Nd、S、Pb同位素证据  

Geological and Sr-Nd-S-Pb isotopic constraints on the genesis of the Baiyinchagan tin polymetallic deposit,southern Great Xing’an Range,China

作　　者：姚磊 吕志成[3,4] 叶天竺 庞振山[3,4] 贾宏翔 张志辉[3,4] 贾儒雅 吴云峰 YAO Lei;LüZhiCheng;YE TianZhu;PANG ZhenShan;JIA HongXiang;ZHANG ZhiHui;JIA RuYa;WU YunFeng(China Mining News,Beijing 100037,China;International Mining Research Center,China Geological Survey,Beijing 100037,China;Development and Research Centre,China Geological Survey,Beijing 100037,China;Mineral Exploration Technical Guidance Center,Ministry of Natural Resources,Beijing 100034,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;Yinman Mining Co.,Ltd,Xi Ujimqin Banner 026200,China)

机构地区：[1]中国矿业报社,北京100037 [2]中国地质调查局国际矿业研究中心,北京100037 [3]中国地质调查局发展研究中心,北京100037 [4]自然资源部矿产勘查技术指导中心,北京100034 [5]中国地质科学院矿产资源研究所,北京100037 [6]西乌珠穆沁旗银漫矿业有限责任公司,西乌珠穆沁旗026200

出　　处：《岩石学报》2021年第6期1731-1748,共18页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41802115);中国地质调查局项目(DD20160052、DD20190570、DD20190166、DD20201181)联合资助。

摘　　要：白音查干矿床是大兴安岭南段新发现的一处大型Sn多金属矿床。为查明该矿床Sn成矿作用与Ag-Pb-Zn成矿作用的关系,本文开展了矿床地质、萤石和石英斑岩Sr-Nd同位素、硫化物S-Pb同位素和原位S同位素地球化学特征研究。SrNd同位素分析结果显示,所有萤石样品均具有相近的(87Sr/86 Sr)i、(143Nd/144Nd)i和εNd(t)值范围,而且与石英斑岩的Sr-Nd同位素组成基本一致,说明矿床各成矿阶段的萤石具有相同的成因,与石英斑岩岩浆作用关系密切。单矿物和原位S同位素数据显示,Ⅰ区Ag-Pb-Zn矿石中的硫化物δ^(34)S值范围(-13.9‰~-4.8‰)与ⅢSn矿石硫化物的δ^(34)S值范围(-12.5‰~-5.3‰)基本一致;而且,Ⅰ区闪锌矿原位δ^(34)S值变化范围较小且较为均一(-12.4‰~-7.3‰,平均为-9.2‰),与石英斑岩"Zn-F-B集合体"中闪锌矿原位δ^(34)S值变化范围(-10.6‰~-9.0‰,平均为-9.7‰)基本一致,说明S可能主要来源于石英斑岩岩浆。Pb同位素特征显示,Ⅰ区Ag-Pb-Zn矿石中的硫化物Pb同位素组成(^(206)Pb/^(204)Pb=18.177~18.200、^(207)Pb/^(204)Pb=15.519~15.531、208 Pb/^(204)Pb=37.985~38.053)与石英斑岩Pb同位素组成(^(206)Pb/^(204)Pb=18.206~18.235、^(207)Pb/^(204)Pb=15.529~15.530、^(208)Pb/^(204)Pb=38.025~38.036)基本一致,说明Ag-Pb-Zn成矿作用的Pb可能主要来源于石英斑岩岩浆。结合矿床地质特征、Sr-Nd、S、Pb同位素数据可知,白音查干矿床Sn成矿作用与Ag-Pb-Zn成矿作用具有密切的成因联系,矿床成矿流体和成矿物质可能主要来源于石英斑岩岩浆。The Baiyinchagan deposit is a newly discovered large-scale Sn polymetallic deposit in the southern Great Xing’an Range.Geological,geochemical,fluorite and quartz porphyry Sr-Nd and sulfide S-Pb isotopic data are used in this paper to address the relationship between Sn and Ag-Pb-Zn mineralizations of the deposit.Sr-Nd isotopic compositions show that all the quartz porphyry and fluorite samples have similar range of(87 Sr/86 Sr)i,(143 Nd/144 Nd)i andεNd(t)values,indicating that fluorite is associated with quartz porphyry,and its ore-forming fluid is derived from the magma of the quartz porphyry.Sulfur isotopic data demonstrate that Ag-Pb-Zn ores of the No.Ⅰarea(δ^(34)S=-13.9‰~-4.8‰)and Sn ores of the No.Ⅲarea of the deposit(δ^(34)S=-12.5‰~-5.3‰)have similar range ofδ^(34)S values,and sphalerite(δ^(34)S=-12.4‰~-7.3‰,mean-9.2‰)and"Zn-F-B aggregates"in quartz porphyry(δ^(34)S=-10.6‰~-9.0‰,mean-9.7‰)also have a same range of in-situδ^(34)S values,suggesting that the magma of quartz porphyry is the main source for sulfur.Pb isotopic data show that the Ag-Pb-Zn ores of the No.Ⅰarea(^(206)Pb/^(204)Pb=18.177~18.200,^(207)Pb/^(204)Pb=15.519~15.531,^(208)Pb/^(204)Pb=37.985~38.053)have similar Pb compositions to those of quartz porphyry(^(206)Pb/^(204)Pb=18.206~18.235,^(207)Pb/^(204)Pb=15.529~15.530,^(208)Pb/^(204)Pb=38.025~38.036),indicating that Pb of the Ag-PbZn mineralization was from magma of quartz porphyry.The geological,Sr-Nd and S,Pb isotopic evidence show that the Baiyinchagan Sn mineralization and Ag-Pb-Zn mineralization are genetically related to each other and their ore-forming fluids and materials were derived from the magma of quartz porphyry.

关 键 词：大兴安岭南段 白音查干 SR-ND同位素 S-Pb同位素 Sn成矿作用 Ag-Pb-Zn成矿作用 

分 类 号：P597.2[天文地球—地球化学] P618.44[天文地球—地质学]