【摘要】 采用电子探针显微分析(EMPA)和粉末X射线衍射(XRD)分析了采自乌拉山金矿床含金钾长石石英脉、石英脉以及其他类型岩石中的10 0多个钾长石样品的化学成分和结果状态,并采用R和Q模式聚类分析、Spearman等级相关分析方法对实验数据进行了统计分析。结果表明,含金矿脉、岩浆热液脉和蚀变花岗岩中的钾长石为中等到最大微斜长石,其特征为K2 O含量高,但相对而言,Na2 O、CaO和BaO的含量低。其他岩石类型中的钾长石的化学成分和结果状态变化很大,可以从透长石、正长石到微斜长石,其特征为K2 O的含量相对较低,但Na2 O、CaO和BaO的含量相对较高。含金样品中的钾长石通常更富K2 O ,表明金的成矿作用与富钾的热液流体和碱质交代作用有关。乌拉山金矿床的成矿作用分为两个阶段,主要的含金钾长石石英脉中的钾长石富K2 O ,形成温度为30 7～379℃,平均为35 3℃;第二阶段含金石英脉中的钾长石含K2 O较低,形成温度为2 6 0～318℃,平均为2 81℃。这些结果表明成矿流体与岩浆热液作用有关,流体朝温度降低、K2 O含量降低的方向演化,K2 O含量高的热液流体和2 6 0～380℃的形成温度有利于金的成矿作用。更多还原

【Abstract】 More than one hundred K feldspars were collected from gold-bearing Vein Ⅰ (K feldspar-quartz vein) and Vein Ⅱ (quartz vein) as well as various other rock types in the Wulashan gold deposit, China. Chemical compositions of K feldspars were analyzed using electron microprobe analysis (EMPA). The powder X-ray diffraction (XRD) patterns of K feldspars were collected using Cu Kα source. Au contents of the corresponding ore samples were analyzed by fire assay. Q- and R-mode cluster analysis and Spearman rank correlation analysis of the experimental data were performed. The results indicate that K feldspars from gold-bearing veins, magmatic hydrothermal veins and altered wall rocks are intermediate to maximum microclines characterized by higher content of K-2O, lower contents of Na-2O, CaO and BaO, and relatively small variations in chemical compositions. K feldspars from other rock types are likely sanidine, orthoclase or microclines that show greater variations in chemical compositions and are characterized by lower content of K-2O but higher contents of Na-2O, CaO and BaO. K feldspars from auriferous samples are much richer in K-2O, indicating that gold mineralization might have been related to potassic hydrothermal fluids and intense K feldspar metasomatism. There exist two gold mineralization stages in the Wulashan deposit. K feldspars from the major K feldspar-quartz veins are characterized by higher K-2O and higher formation temperatures of 307～379℃ with an average of 353℃. K feldspars from the quartz veins of the second stage are characterized by lower K-2O and lower formation temperatures of 260～318℃ with an average of 281℃. These results indicate that the mineralization fluids were associated with magmatic hydrothermal events and evolved toward lower temperatures and lower content of K-2O, but the hydrothermal fluids of higher K-2O and the temperatures of 260～380℃ may favor gold mineralization.更多还原