豫西熊耳山地区吉家洼金矿床成矿物质来源探讨——碳、氧、硫、铅同位素地球化学证据  

C, O, S and Pb isotopic constraints on ore-forming material sources of Jijiawa gold deposit in Xiong'er Mountain area, western Henan

作　　者：张兴康[1,2] 叶会寿[2] 张维 张福斌 何旭麒 张向存 

机构地区：[1]河北省地质调查院,河北石家庄050081 [2]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037 [3]河南省地矿局第四地质勘查院,河南郑州450001 [4]河南省地矿局第三地质矿产调查院,河南郑州450003

出　　处：《矿床地质》2017年第3期595-610,共16页Mineral Deposits

基　　金：中国地质调查局地质调查项目(编号:1212011220869);国土资源部成矿作用与资源评价重点实验室开放研究项目(编号:ZS1314)的联合资助

摘　　要：吉家洼金矿床位于豫西熊耳山金多金属矿集区中西部,矿体产出受断裂构造控制,属构造蚀变岩-石英脉型金矿床。为了查明吉家洼金矿床的成矿物质来源,本次对矿床的碳、氧、硫、铅等同位素进行了系统研究。研究结果表明,吉家洼金矿的δ^(13)C_(V-PDB)介于-10.3‰^-7.7‰之间,δ^(18)O_(V-SMOW)介于14.2‰~17.8‰之间,表明成矿流体中的碳来源于岩浆。硫化物δ^(34)S值介于-20.4‰^-5.4‰,表明硫来源于早白垩世花山花岗岩基,造成硫化物的δ^(34)S值呈现出较大负值的原因可能是在成矿过程中成矿流体物理化学条件的变化引起硫同位素发生分馏所致。铅同位素组成为^(206)Pb/^(204)Pb=17.042~18.149,^(207)Pb/^(204)Pb=15.333~15.575,^(208)Pb/^(204)Pb=37.675~38.868,与由新太古界—古元古界太华群岩石重熔形成的早白垩世花岗岩的铅同位素组成相似,具有壳幔混合源的特点。综合碳、氧、硫、铅等同位素的研究结果认为,吉家洼金矿床的成矿流体来源于岩浆热液,并有大气降水的加入;成矿物质主要来源于早白垩世花岗岩,矿床成因属岩浆期后热液脉状金矿床。The Jijiawa gold deposit is located in the western part of the Xiong＇er Mountain gold polymetallic ore concentration area, Henan Province. The formation of orebodies was controlled by the subsidiary fault which was located in the faulted structure belt. Based on systematic field study of isotopes such as C, O, S and Pb, the authors focused on the source of ore-forming materials. With the δ^13CV-PDB values ranging from -10.3‰ to -7.7‰ and the δ^18OV-SMOW ranging from 14.2‰ to 17.8‰, the C-O isotopes composition reveals that C isotope originated in magmatic-dominated fluid. The δ^34S values vary from -20.4‰ to -5.4‰, suggesting that S isotope originated in early Cretaceous Huashan granite. In the process of mineralization, the change of physico-chemical conditions led to sulfur isotope fractionation, which is probably the reason that the δ34S presents a large negative value. The ^206Pb/^204Pb ratios are 17.042~18.149,^ 207Pb/^204Pb ratios are 15.333~15.575 and ^208Pb/^204Pb ratios are 37.675~38.868, suggesting that Pb has a characteristic of crust-mantle mixed source, and it is similar to Early cretaceous granites in lead isotope composition. Based on the study of C, O, S, Pb isotopes, the authors consider that the hydrothermal system was gradually transitional from a magmatic-dominated fluid to a meteoric-dominated fluid, and early Cretaceous granite contributed main metallogenic materials. The Jijiawa Au gold deposit genetically belongs to magmatic hydrothermal vein gold deposit.

关 键 词：地球化学 碳、氧、硫、铅同位素 成矿物质来源 吉家洼金矿 熊耳山地区 

分 类 号：P618.51[天文地球—矿床学]