陕西双王金矿床钠长石化与钠长石角砾岩特征

通过矿相学、电子探针、岩石化学分析等方法研究了双王金矿床矿石的造岩矿物特征及蚀变分带特征。发现钠长石中Na2O含量为7.39%~12.22%,钠长石化学成分与钠长石端元成分基本一致,为比较纯的钠长石,且具有多期成因,但其成分变化不大,钠质流体可能为同源流体。含铁白云石中铁的含量较高,样品中除两个样品Mn O含量小于0.15%外,其余样品中的Mn O含量均大于0.15%,具有与白云鄂博火成碳酸岩相似特征,且与镁电气石共伴生,显示具有岩浆气液成因特征,双王金矿钠长铁白云石角砾岩可能为碳酸岩岩浆热液侵入隐爆成因。双王金矿床钠化蚀变与铁白云石蚀变为中心对称型,角砾岩体蚀变最强,向两侧减弱。角砾岩中Na2O含量为8.25%~9.84%,达到了钠长石矿的工业品位,钠长石纯度较高,因此,在双王金矿床及尾矿中,钠长石具有综合利用价值。

Characteristics of Albitization and Albite Breccia in Shuangwang Gold Deposit,Shaanxi Province

The characteristics of rock-forming minerals and the zoning characteristics of alteration in Shuangwang Gold Deposit are studied by mineralograpy，electron probe micro analysis and rock chemical analysis method.The study results show that，the content of Na2O in albite is between 7.39% and 12.22%.The chemical composition of Albite is consistent with its end-member component，so it is relatively pure albite with feature of multi-phase mineralization.Due to little change in its composition，sodic fluids may be homologous.Iron content is higher in ankerite，and the components of MnO are more than 0.15% in almost all the samples except for two samples.The characteristics of ankerite are similar to that of carbonatites in Bayan′obo.Associated with dravite，ankerite has characteristics of gas-liquid magma.The albite ankerite breccia may be the factor for magmatic hydrothermal cryptoexplosion in Shuangwang deposit.Albitization in Shuangwang gold deposit has a central symmetry with ankerite alteration.Breccia alteration is maximum，and its intensity is gradually weakened to the sides.The content of Na₂O in breccia varies between 9.84% and 8.25%，which has reached industrial grade of albite with high purity.Therefore，albitite existing in Shuangwang gold deposit and tailings has a value for comprehensive utilization.