陕西八卦庙金矿钠长石的成因  

The Genesis of Albite in the Baguamiao Gold Deposit, Shaanxi Province

作　　者：王学明[1] 汪东波[1] 邵世才[1] 冯建忠[1] 陈梦熊 

机构地区：[1]北京矿产地质研究所 [2]国家有色金属工业局地质总局,北京100814

出　　处：《矿床地质》2001年第3期223-228,共6页Mineral Deposits

基　　金：重点基础研究项目 (G19990 43 2 15 );国家攻关项目 (96_914_0 1_0 4);有色金属工业局地质总局项目 (98_D_1)联合资助

摘　　要：陕西八卦庙金矿产于凤太矿田北部 ,含矿地层为上泥盆统星红铺组下段中上部。赋矿围岩中含有较多的钠长石。钠长石呈层状顺层产出 ,镜下观察为砂屑状、次棱角状 ,与石英及铁白云石呈镶嵌粒状关系 ,而无交代结构 ;钠长石成分计算其形成温度超过 80 0℃和 40 0℃ ,表明其形成与喷流作用有关 ,并受到后期变质改造 ;据钠长石X射线衍射分析 ,其有序度为 0 .38,形成温度为 6 2 0～ 6 6 7℃ ,说明它不是一般意义上的热水沉积岩产物。上述研究表明 :八卦庙金矿中的钠长石是火山喷发沉积_变质重结晶的产物 ,火山沉积作用参与该地区成矿是形成巨型金矿的最有利条件。含钠长石硅质岩、千枚岩。The Baguamiao gold deposit is located in the northern part of the Fengtai orefield. It occurs in the lower part of the Upper Devonian Xinghongpu Formation, which contains lots of albite existent along the bedding in the layered form. Microscopic identification shows that the albite is in the psammitic and subangular forms. It assumes mosaic texture with quartz and carbonate, but without metasomatic texture. The forming temperature of albite based on its chemical composition is higher than 800℃ and higher than 400℃, suggesting that its formation was related to volcanic effusion and later metamorphism. According to X_ray analysis, its degree of order is 0.38, and its forming temperature is 620～667℃, implying that it is not a product of ordinary hydrothermal sedimentation. The above studies show that the albite in the Baguamiao gold deposit was formed by volcanic effusive sedimentation and metamorphic recrystallization. Therefore, the metallization related to volcanic sedimentation constitutes an important prerequisite for the formation of large_size gold deposits in this area. The association of albite_bearing silicolites, phyllite and limestone seems to be an important prospecting indicator.

关 键 词：金矿床 钠长石 火山喷发沉积 变质重结晶 陕西 成因 火山 沉积作用 找矿标志 

分 类 号：P618.51[天文地球—矿床学] P578.968[天文地球—地质学]