QUARTZ VEINS AND THEIR FEATURES OF MICRO-GRAIN TYPE DISSEMINATED GOLD DEPOSITS IN NORTH-WESTERN SICHUAN PROVINCE
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摘要: 川西北地区是我国主要的微细浸染型金矿化集中区之一, 产有马脑壳等2 0余处重要金矿床(点).研究表明, 区内此类金矿床范围内常发育多种类型的石英脉体, 其中黄铁矿-毒砂-石英脉、石英-辉锑矿脉及石英-雄(雌) 黄脉与金矿化关系密切, 是主要金矿化阶段产物, 它们在空间上多分布于矿化带范围, 其发育程度在一定意义上指示金矿化作用的强度, 因而构成区内该类金矿床找矿评价的重要宏观标志.流体包裹体研究表明, 上述类型的石英脉主要形成于温度为170~ 2 10℃及盐度w(NaCl) 为4%~ 11%的热液条件下, 其热液气相成分中w(CO2) /w(H2O) 比值一般变化于0.240~0.491, 石英红外吸收光谱相对光密度D(H2O)/D(CO2)值一般小于8.0, 与其他类型石英脉具明显区别, 因而上述参数值构成了该区金矿床找矿评价的重要石英脉微观标志.Abstract: The north-western Sichuan Province, one of the main micro-grain disseminated gold metallogenic zone in China, possesses about twenty important gold deposits (or occurrences) such as Ma'naoke etc. Studies show that several kinds of quartz veins are often developed in the mining districts in this region, among which pyrite-arsenopyrite-quartz, quartz-stibnite as well as quartz-realgar (orpiment) veins are intimately related with gold mineralization and their spatial distribution is mainly constrained in the gold mineralization belts. While the development degree of these three kinds of quartz veins can indicate gold mineralization intensity to some extent, so they are important macroscopic marks for exploration and evaluation of this type of gold deposits in the region. Studies on fluid inclusions show that these kinds of quartz veins formed in a hydrothermal condition with temperature range from 170 ℃ to 210 ℃ and salinity of fluids range from 4% to 11%, the w(CO2) / w (H2O) value of the gaseous compositions of fluid inclusions is between 0.240 and 0.491 in general, and the relatively light density values of quartz are usually lower than 8.0. All these are obviously different from other kinds of quartz veins, so these parameters of quartz form the important microscopic marks for exploration and evaluation of gold deposits in the region.
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图 1 马脑壳金矿床地质-构造略图
1.石炭—二叠系; 2.扎尕山组; 3.杂谷脑组; 4.侏倭组; 5.花岗斑岩脉; 6.矿体; 7.压-(扭) 性断层; 8.剪切断层; 9.地质界线; 10.地层产状
Fig. 1. Geological-structural outline of Ma'naoke gold deposit
图 2 流体包裹体均一温度-盐度关系
Fig. 2. Relationship between homogenization temperature and salinity of fluid inclusions
图 3 流体包裹体气相组分w (H2O)-w (CO2)-w (CO+CH4+H2) 三角图解(图例同图 2)
Fig. 3. Triangle diagram of gaseous w (H2O)-w (CO2)-w (CO+CH4+H2) compositions of fluid inclusions
图 4 石英的红外吸收光谱
LX-4-1.Ⅰ类石英; MPD5W-2.Ⅱ类石英; W11. Ⅲ类石英; LZ-PD-I.Ⅴ类石英
Fig. 4. Infrared absorption spectrum map of quartz
图 5 石英的红外吸收光谱参数D (CO2) /D (SiO2)-D (H2O) /D (CO2) 关系图解(图例同图 2)
Fig. 5. Relationship diagram between D (CO2) /D (SiO2) and D (H2O) /D (CO2) of infrared absorption spectrum of quartz
表 1 主要矿物含金量测试分析结果
Table 1. Gold-content tested results of main minerals
表 2 流体包裹体气相成分分析结果
Table 2. Analytical results of gaseous phase of fluid inclusions
表 3 石英的红外吸收光谱特征参数统计结果
Table 3. Statistic results of characteristic parameters of infrared absorption spectrum of quartz
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