湖南新宁金家锑矿床地质-地球化学特征

Geochemical characteristics of the Jinjia antimony deposit in Xinning county,Hunan Province

湖南新宁金家锑矿床是湘中地区较具有经济价值的锑矿床。文章通过矿石稀土元素、微量元素、铅同位素分析以及流体包裹体岩相学观察、均一法测温和包裹体气液相成分分析,研究了金家锑矿床成矿流体的性质及演化。研究表明:①矿石中稀土元素总量w(ΣREE)=151.21×10-6～212.41×10-6,平均180.52×10-6;LREE/HREE=15.21～18.54,轻稀土富集,具中等负铕异常;矿石微量元素蛛网图表明,富集Rb,U,Th等大离子亲石元素(LILE),而亏损Nb,Ta,Ti等高场强元素;铅同位素组成206 Pb/204 Pb=18.032～18.391,207 Pb/204 Pb=15.403～15.495,208Pb/204Pb=38.025～38.215,表明成矿物质来自深源;②流体包裹体主要为气液两相包裹体,液相成分阳离子以K+,Na+,Ca2+,Mg2+为主,阴离子以SO24-,Cl-,F-为主;气相成分以H2O,CO2,CH4为主。包裹体均一温度100～240℃,主要为140～200℃,盐度2.60%～3.80%,表明金家锑矿床为典型的中低温热液矿床,其成矿流体为中-低温、低盐度热液。

Jinjia antimony deposit is a economic ore deposit inXiangzhong （Middle Hunan） area. Accord ing to the analysis of REE, trace elements, Pb isotopes,gas-liquid composition of fluid inclusions and pet rographic observation of the ore, nature and evolution of ore fluid are studied. The analysis indicates that： @FREE is from 151.21×10 6 to 212.41×10 6 average at 180.52×10 6, enriched in LREE, and displays right-inclined REE patterns with pronounced negative Eu anomalies in the chondrite normalized REE diagrams; the ore is rich in I.ILEs of Rb,U and Th, depleted Nb,Ta and Ti based on the primitive mantie normalized trace element spider diagram; 206Pb/204Pb in range of 18. 032 to 18. 391, 207pb/204Pb in range 15. 403 to 15. 495, 208Pb204pb in range of 38. 025 to 38. 215 indicate mainly mantle source of the ore- forming materials; （2）mainly gas and liquid, two phase occur in fluid inclusions, in liquid phase K＋ ,Na＋ , Ca2＋ ,Mg2＋ are the main cations and SO24 ,C1 ,F the main anions; in gas phase H20,CO2,CH4 are dominated. Homogenization temperature is 100 240 ℃ but concentrated at 140-200 ℃. Salinity is 2.60% 3.80%. The data above show that this deposit is a meso-epithermal antimony deposit.