湘西柳林汊金矿带中钠长石的矿物学和地球化学特征

钠长石广泛分布于湘西柳林汊金矿带的含金脉体中,利用显微镜下鉴定、X荧光光谱(XRF)、X射线衍射(XRD)、电感耦合等离子体质谱(ICP-MS)等分析手段对该区金矿床的钠长石进行了系统的研究.结果表明:该区粉红色、肉红色钠长石镜下呈板条状、粒状,解理不发育,双晶以聚片双晶为主,负低突起,干涉色一级灰白到一级淡黄;钠长石的Ab、An、Or的变化范围分别为97.32%～99.74%、0.12%～2.5%、0.13%～0.47%;该区钠长石的平均有序度都大于0.905,形成温度均在226～395℃之间;钠长石稀土含量普遍较低,在不同程度上都有LREE的富集,无明显的Eu、Ce异常.钠长石矿物学、地球化学特征均反映了该含金钠长石-石英脉是由热液作用形成.

Mineralogy and Geochemistry of Albties from the Liulincha Gold Ore Belt,Western Hunan Province, China

Albite is widespread in the Liulincha gold ore belt in western Hunan Province, China. In this study, al-bites from this area were collected and systematicly studied. The microscope analysis showed characteristics of those albites can be listed as follows: the pink-red albites occur as lamellae and grains, weakened cleavage, polysynthetic twin, negative relief, and grey to yellowish (interference) colors. With the methods of X-ray Fluorescence and X-ray power diffraction, the compositions and degrees of ordering of albites collected from four gold deposits in the Liulin-cha gold ore field were determined. Ab, An, and Or in albite varied in the ranges of 97.32% ～99.74% , 0. 12% ～2. 5% , and 0. 13% ～0.47% , respectively, and all of the average degrees of order were higher than 0.90. The for-mation temperatures of albites varied between 226 and 395℃. The albites contained minor amount of REE, and the LREE concentrations were usually relatively high, without obvious anomaly of Eu and Ce. The study revealed that the gold-bearing albite-quartz veins were of hydrothermal origin rather than magmatic origin.