广西金牙金矿床石英的标型特征及其意义

TYPOMORPHIC CHARACTERISTICS AND SIGNIFICANCE OF QUARTZ FROM JINYA GOLD DEPOSIT, GUANGXI

本文通过对金牙金矿床石英的化学成分、包裹体、物理性质及稳定同位素等万面的矿物学特征研究,取得了有价值的成因信息和找矿标志。认为该矿床属浅成中低温地下热(卤)水渗滤型金矿床,成矿物质来源于地层围岩。还指出石英颗粒极细小,多为隐晶至微晶,自形程度低,呈白色或无色、透明;比重低,晶胞棱长a_o大而Co小、单位晶胞体积增大(与标准石英比);红外光谱有1个宽峰、4个吸收峰和2个强的特征峰的波段,具单峰或双峰发热光曲线(在50～350℃范围内);具结构铝,含Ca、Fe、Mn、Au、Ag、Co、Ni、Se、Te与∑REE等杂质元素,其中Au与Al成正相关,而Au与∑REE呈负相关;包裹体呈无色透明、个体细小且少,以液相为主.气液比低,且出现沸腾包体群,其含盐度低,无子矿物,Na、Ca较高,为富含CO_2,CH_4的Ca^(-2)-Na_a-HCO_3~1-Cl型地下热(卤-水(温度305～190℃、压力25669～16945kpa.深度小于1km);δ^(18)O、δ^(18)O_(H_2O)、δD值具大气降水特征,δ^(13)C值类似油田碳等特征,是找“金牙型”金矿的重要找矿标志。

The author has gotten valuable genetic data and prospecting marks of gold deposit through study on the chemical composition . inclusions, physical property and stable isotopas of quartz from Jinya gold deposit. Guangxi. The paper considers that the gold deposit is a shallowly meso-epithcrmal groundwater (hot brine) infiltration-type gold deposit. The ore-forming material comes from enclosing strata. The quartz is very fine(mostly crypte-crystal-micromite) in granularity, low in idiomorphism , white and colourless in colour, transparent, low in specific gravity, long in ac and short in c0 of crystal edge, bigger in volume of unit cell (than that of the standerd quartz). The quartz also has the infrared spectrum band with a broad peak, four obsorption peaks, two strong characteristic peaks, and the hot luminescent curve with single or double peaks (ranging 50°-350 C). The quartz contains structeral Al, Ca, Fe, Mn. Au, Ag, Co, Ni, Se, Te and REE. among which, Au is in direct proportion to Al, but in inverse proportion to REE. The inclusions in quartz are colourless, transparent, rare, small, low in salinity, rich in Na and Ca, free from daughter minerals, and dominated by liquid and a little by gas. Sometimes, the boiling inclusions appear in groups. So, the inclusions are from Ca2- -Na -HCO -Cl- type ground warm(brine ) water rich in CO2 and CH4 with the temperature of 305-190C . the pressure of 25669-16845 KPa and the deepness of less than one Km. The δ18O. δ18OH2O and δD values are characterized by meteoric water,the δ13C value similarly by oilfield carbon. All these data are important prospecting guides for 'Jinya - type 'gold deposit.