四川宝兴县黄店子地区富钾粗面岩类的岩石特征

四川宝兴黄店子富钾粗面岩,是目前国内外已知含氧化钾最高的粗面岩之一。其氧化钾含量已达含钾岩石作为钾肥原料的富矿标准。 富钾粗面岩是一套巨厚的海相火山岩系。组成该岩石的矿物成分较单纯。斑晶和基质95％以上均为钾长石,不含斜长石、暗色硅酸盐矿物和付长石类矿物。钾长石绝大部分为中三斜正长石,其平均成分为Or87Ab13,并开始向中微斜长石转化。岩石化学以SiO2饱和,铝过饱和、富K2O、贫Na2O、CaO、FeO和TiO2为其特征。它们是前寒武纪滇青藏洋坂块与扬子板块分界线附近玄武岩浆向碱性岩浆分异演化的终极产物。

THE PETROGRAPHIC CHARACTERS OF POTASIUM-RICH TRACHYTE OF HUANGDIANZI GROUP IN BAOXING COUNTY, SICHUAN PROVINCE

The potassium ich trachyte in Huangdianzi, Baoxing county, Sichuan province, is one of the high K content rocks known in our country and abroad. The content of its K20 is rich enough that it may be used as a K-fertilizer.It occurs in a thick formation of marine volcanic rock. Its mineral composition is very simple. More than 95% of the phenocryst and matrix are composed of" potash feldspar. There are no plagioclace, dark silicates and felspathoids in the rock. Most of the potash eldspars are triclinic andesine with an average comnosition of Or87Ab13, and they transform gradually into triclinic andesine. The rock is characterized chemically by saturation with Si02 and oversaturation with Al, and also by its rich in K20, lack of Na2O, CaO, FeOandTi02, They are the end products of differentiation from basaltic magma to alkaline magma, taking place near the boundery between the Yangtze Plate and the Dian-Qing-Zhang (Yunnan-Qinghai-Xizhang) Oceanic Plate.