北秦岭河南省南召县水洞岭铜锌矿形成机制

摘要

The Shuidongling Cu-Zn deposit, Nanzhao County, Henan Province, is situated in the Northern Qinling Orogen. It belongs to the Dongjie-Baishijian-Shuidongling polymetallogenic belt. In this paper, based on field geological investigation, writers discussioned on the metallogenesis of this deposit by employing multiple techniques of fluid inclusions microscopic measurements, analysis of H, 0, S, and Pb isotopic compositions as well as K/Ar isotopic age. Analysis of fluid inclusions indicates that the inclusions are primarily liquid enriched vapor liquid inclusions, and their homogenization temperature ranges mainly from 98 ℃ to 354℃ , while the salinity ranges mainly from 0. 1% to 19. 99% NaCleq. Laser Raman spectra shows that the main composition of the ore-forming fluids is H2O with small amount of CO2. Hydrogen and oxygen isotopic compositions suggest that the fluids for mineralization should mainly have experienced mixing process of magmatic water and meteoric water. δ34Sv. CDT of ores ranges in 1. 82‰ ~9. 67‰, n(206Pb)/rc(204Pb) , n(207Pb)/n(204Pb) and n(208Pb)/rc(204Pb) vary in 17. 341 ~ 17. 930, 15. 490 ~ 15. 573, and 37. 266 ~ 37. 960, respectively. All the isotopic composition are characterized by changing in narrow ranges and relatively homogeneous. It is indicated that the ore forming materials is mantlely derived. But, there may be a part of the crust material mixed during ore forming processes. K/Ar isotopic ages of biotite and muscovite set respectively for 376.2 ±3. 8 Ma and 350. 8 ±3.5 Ma, equivalent to Late Paleozoic. All the results suggest that the Shuidongling Cu-Zn deposit should belong to transformational type deposits.%河南省南召县水洞岭铜锌矿床位于北秦岭造山带,隶属于洞街—白石尖—水洞岭多金属成矿带.本文在野外地质工作基础上,运用流体地球化学和同位素地球化学等方法,依据流体包裹体特征和H-O-S-Pb同位素组成以及K/Ar年龄,探讨了矿床的形成机制.研究表明:流体包裹体主要以富液相的两相水溶液包裹体为主,均一温度介于98～354℃之间,盐度介于0.1% ～ 19.99% NaCleq之间；激光拉曼分析表明成矿流体以H2O为主,含有少量CO2.H、O同位素研究表明,成矿流体为岩浆水和大气水混合成因；矿石硫同位素δ34SV-CDT介于1.82‰～9.67‰之间,矿石铅同位素比值n(206Pb) /n(24pb)、n(207pb)/n(204pb)和n(208Pb)/n(204 Pb)分别介于17.341～17.930、15.490～ 15.573、37.266～37.960之间,具有变化范围窄,相对均一的特点,反映了成矿物质主要为幔源,由于成矿过程受岩浆活动的影响,可能混入部分地壳物质.黑云母和白云母K/Ar年龄分别为376.2±3.8 Ma和350.8±3.5 Ma,相当于晚古生代.以上研究表明,水洞岭铜锌矿床属于热液改造型矿床.