杨天云露1,彦廷龙1,陈 伟1,陆 亮2.滇东北银厂Pb-Zn矿床成矿物质来源研究[J].有色金属(矿山部分),2019,71(1):37-43.
滇东北银厂Pb-Zn矿床成矿物质来源研究
Study on the source of ore-forming materials in Yinchang lead-zinc deposit, northeastern Yunnan
  
DOI:10.3969/j.issn.1671-4172.2019.01.009
中文关键词:  银厂Pb-Zn矿床  成矿物质来源  主微量元素  REE  硫同位素
英文关键词:Yinchang lead-zinc deposit  source of ore-forming material  major and trace element  REE  δ34S
基金项目:
           
作者单位
杨天云露1 (1. 昆明理工大学 国土资源工程学院,昆明 650093
2. 云南南方地勘工程总公司,云南 大理 671000)
彦廷龙1
陈 伟1
陆 亮2
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中文摘要:
      银厂铅锌矿床是滇东北会泽地区矿山厂—金牛厂构造带中部典型的灯影组铅锌矿床,矿体产出受层位、岩性和构造控制明显,呈似层状、脉状及透镜状产于上震旦统灯影组白云岩中。矿石矿物以闪锌矿和方铅矿为主,次为少量黄铜矿和辉银矿,脉石矿物主要有重晶石、白云石和石英。本文通过对银厂铅锌矿床矿石主微量、REE和不同阶段单矿物S同位素组成进行测试分析。结果表明,矿石微量元素Ge和Tl含量分别为2.12~3.07×10-6(平均2.68×10-6)和1.22~2.15×10-6(平均1.61×10-6),稀土总量为31.39~73.94×10-6(平均49.27×10-6),变化范围较大,总体呈现比较平缓的右倾型稀土元素配分模式,LREE/HREE为2.60~3.84(平均3.02),LaN/YbN为2.63~3.84(平均3.02),具有轻稀土元素相对富集、分异程度相对较低特征。矿区重晶石的硫同位素以富的δ34S为特征,介于26.8‰~29.3‰,平均27.8‰,沉积期黄铁矿δ34S值介于-7.2‰~5‰,变化范围较宽,平均-0.25‰;而热液改造期硫化物的δ34S组成相对稳定,变化范围8.4‰~13.2‰,平均10.76‰,该阶段同一手标本中δ34S闪锌矿>δ34S方铅矿,暗示S同位素分馏达到平衡,成矿流体的δ34S∑S值相当于硫化物的平均δ34S值(10.76‰)。根据矿石主微量、稀土元素含量和与矿区不同时代地层和峨眉山玄武岩进行对比,认为成矿物质来源具有“多源性”,成矿元素主要来源于上震旦统灯影组围岩和峨眉山玄武岩,S主要来源于赋矿地层中的硫酸盐和早阶段形成的重晶石,生物还原作用(BSR)是沉积期还原硫形成的关键机制,而改造期的S则主要是硫酸盐矿物热化学还原(TSR)作用的产物。
英文摘要:
      Yinchang lead-zinc deposit is located in the central part of mining plant-Jinniu plant tectonic belt, which is the typical Dengying-formation lead-zinc deposit in Huize County, northeastern Yunnan. The ore body output is obviously controlled by stratification, lithology and structure, with shape of layered, veined and lenticula produced in the Upper Sinian Dengying formation dolomite. The ore minerals are mainly composed of sphalerite and galena, and a small amount of chalcopyrite and argentite. The gangue minerals are mainly barite, dolomite and quartz. Based on the study of geochemical characteristics and sulfur isotope tracing of ore, the results indicated that the content of Ge and Tl were concentrated in (2.12~3.07)×10-6(average of 2.68×10-6)and (1.22~2.15)×10-6(average of 1.61×10-6), respectively. The content of ΣREE varied widely ranging from (31.39~73.94)×10-6(average of 49.27×10-6), showing a relatively gentle right-handed REE distribution pattern. LREE/HREE ranged from 2.60 to 3.84 (average of 3.02); and the LaN/YbN was between 2.63 and 3.84 (average of 3.02), with the characteristics of relative enrichment of light rare earth elements and relatively low degree of differentiation. The sulfur isotope of barite in the mining area was characterized by rich δ34S(average of 27.8‰), The δ34S value of pyrite in the sedimentary period was between -7.2‰ and 5‰, with a wide range and average of -0.25‰. The δ34S of sulfide in the hydrothermal reformation period was relatively stable, varying from 8.4‰ to 13.2‰(average of 10.76‰). In this stage, δ34Ssphalerite>δ34Sgalena, suggesting S isotope fractionation reached equilibrium, the δ34S∑S value of the ore-forming fluid corresponded to the average δ34S value (10.76‰) of sulfide. The major, trace and rare earth elements of ore were compared with different age strata in the mining area and Emeishan basalt, it was considered that the source of ore-forming materials had “multi-source”, and ore-forming elements were mainly derived from the surrounding rocks of the Upper Sinian Dengying Formation and the Emeishan basalt, S was mainly derived from the sulfate in the ore-bearing stratum and the barite formed in the early stage. Bioreduction (BSR) is the key mechanism for the reduced sulfur formation during the depositional period, while the S in the reforming period is mainly the product of the Thermochemical Sulfate Reduction(TSR) .
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