湖南石门雄黄矿床流体包裹体地球化学特征

GEOCHEMISTRY OF FLUID INCLUSIONS ASSOCIATED WITH THE REALGAR DEPOSIT IN SHIMEN,HUNAN

石门超大型雄黄矿床流体包裹体丰富。包裹体液相成分中富Ｎａ＋、Ｃｌ－和Ｋ＋、ＳＯ２－４，气相成分中Ｈ２Ｏ占绝对优势，少量ＣＯ２，成矿流体化学类型属ＣｌＳＯ４ＮａＫ型水。雄黄、雌黄形成于低温（１８０～９０℃）、低压（２０～５ＭＰａ）、浅成（１７５～７００ｍ）、弱酸性（ｐＨ：４．６７、４．４３）和弱还原（Ｅｈ：－０．２６５Ｖ）条件。流体包裹体氢氧同位素研究表明，成矿流体主要为古大气降水，并混有盆地建造水，大气降水下渗、循环、加热、淋滤形成了中－低盐度［ｗ（ＮａＣｌ）：１６．０３％～４．２７％］，中等密度（０．８６３～１．０６５ｇ／ｃｍ３），含矿地下热水。

The super large sized realgar deposit in Shimen,Hunan,is distinguished by numinous fluid inclusions consisting of liquid phase rich in Na +,Cl -,K + and SO 4 2- and vapor phase comprised of prevailing H 2O and lesser CO 2. Mineralizing fluids fall chemically into a Cl SO4 Na K type water whose precipitations as reagar and orpiment needed lower temperature (180～90℃),lower pressure(20～5MPa),smaller depth (175～700m), slighter acidity (pH:4.67, 4.43) and slighter reduction (Eh=-0.265V). H and O isotopic studies of fluid inclusions suggest that the mineralizing fluids were made up chiefly of paleometeoric water, later mixed with a certain amount of basin formational water and that they could become ore bearing hydrothermal solutions characteristic of low moderate salinity [ W (NaCl)= 16.3% ～ 4.27% ) and moderate density (0.863～1.065g/cm3) only after downward percolating, convecting, being heated and being leaching.