摘要
采用微区X射线衍射(μXRD)、X射线荧光光谱(XRF)、电感耦合等离子体质谱仪(ICP-MS)、扫描电子显微镜(SEM)和显微红外光谱(Miro-FTIR)等岩石矿物学分析测试手段,对某一地区的羊脂黑曜岩的物相组成、显微结构和化学成分等进行了系统研究.结果表明,该羊脂黑曜岩的基本组成特征与其他2个产地的黑曜岩类似,其化学组成都以SiO2、Al2O3、K2O、Na2O为主,属于流纹岩化学成分范围.宏观上表现为非晶质熔体,但熔体内存在微米-亚微米粒径的细小矿物,以羊脂黑曜岩所含微纳米粒径矿物最为丰富.其中所含的钾霞石、磁赤铁矿和黄铁矿都是具有特殊化学性质的矿物,这可能是羊脂黑曜岩的物理化学性质明显优于其他2类黑曜岩的原因.
Abstract
Modem petrological and mineralogical analytical and testing methods,such as Microzone X-ray diffraction(pXRD),X-ray fluorescence spectroscopy(XRF),inductively coupled plasma mass spectrometry(ICP-MS),scanning electron microscopy(SEM),micro-infrared spectroscopy(MIRO-FTIR),have been applied to systematically study the phase composition,microstructure and chemical composition of the mutton-fat obsidian from an area.The results show that basic characteristics of the mutton-fat obsidian are similar to those of obsidians from other two sources.They are mainly composed of SiO2,Al2O3,K2O,Na2O,belonging to the chemical composition range of rhyolite.These obsidians consist of amorphous glass on a macroscopic basis,with lots of micro-nano sized minerals in the glass.Especially,the mutton-fat obsidian has most abundantly distributed micro-nano sized minerals including potassium nepheline,magnetic hematite and pyrite which are minerals having special chemical properties.This may be the reason why physicochemical properties of the mutton-fat obsidian are obviously superior to those of other two types of obsidian.
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