美国Spruce Pine与新疆阿尔泰地区高纯石英伟晶岩的对比研究

Characteristics of Granitic Pegmatite with High-Purity Quartz in Spruce PineR egion,USA and Altay Region of Xinjiang,China

对美国北卡罗来纳州Spruce Pine地区白岗岩/伟晶岩和新疆阿尔泰白云母花岗岩/伟晶岩进行了对比研究。这两个地区的伟晶岩可能是过铝质花岗岩浆通过熔体-蒸汽分异作用的产物。美国产高纯石英的伟晶岩发育在片岩、片麻岩的背景之上,主要造岩矿物中富含斜长石,Na大于K,大离子亲石元素Sr和Ba含量高,高场强元素和稀土元素含量低,Eu正异常,石英中杂质元素含量低。这些特征可作为高纯石英伟晶岩的判别标志。我国阿尔泰地区的伟晶岩脉十分发育,所研究的样品中,有些样品已经具有这些特点,阿尔泰伟晶岩区具有产高纯石英的成矿前景。

The alaskites/pegmatites from the Spruce Pine region of USA and the muscovite granites/pegmatites from the Altay region of Xinjiang,China,were comparatively studied.The pegmatites from both regions might be melt-vapor differentiation products of the peraluminous granitic magmas.The pegmatites from the Spruce Pine region with high-purity quartz were developed on the schist or gneiss background,whose major rock-forming minerals are rich in plagioclase,showing high Na/K ratios,high large-ion lithophile elements Sr and Ba contents,low high-field strength and rare earth elements contents,positive Eu anomalies, and low impurity elements contents in quartz.All these characteristics can be used as the discrimination criteria of high-purity quartz pegmatities.The Altay region of Xinjiang is abundant of pegmatites,and some samples studied showed the features which evidenced that the Altay pegmatite region has a perspective to find the gualified pegmatites with high-purity quartz.