北京延庆硅化木的矿物学特征分析

通过X射线荧光、红外光谱和X射线衍射等检测方法分析了延庆硅化木的矿物学特征.结果表明：2个不同植物种属但在同一埋藏地形成硅化木标本成因相似，其颜色与所含元素种类及含量密切相关.X射线衍射分析表明，不同颜色和植物种属的硅化木主要组成物相一致，为SiO2，其他矿物极其微量.2个硅化木标本的红外吸收谱带基本一致，均显示典型的石英质玉石红外吸收光谱，且含有少量吸附水.偏光显微镜下显示2个硅化木标本的主要矿物成分均为隐晶质石英.延庆土城子组硅化木的沉积环境为较浅的湖沼沉积，当时处于半干旱-半湿润的气候条件下，并伴随火山活动.

MINERALOGICAL CHARACTERISTICS OF SILICIFIED WOOD IN YANQING DISTRICT OF BEIJING

The mineralogical characteristics of silicified wood in Yanqing are analyzed by the test methods of X-ray fluorescence(XRF),infrared spectroscopy(IR)and X-ray diffraction(XRD).The results show that the samples of silicified wood of two different plant species but formed in the same burial site are of similar origin,and their colors are closely related to the types and contents of elements in the silicified wood.The XRD analysis indicates that the main compositions of silicified wood with different colors and plant species are consistent,i.e.SiO₂,with small traces of other minerals.The infrared absorption bands of the two silicified wood specimens are basically the same,showing typical quartzite jade infrared absorption spectrum and containing a small amount of adsorbed water.The main mineral composition of the two specimens are cryptocrystalline quartz under the polarized microscope.The sedimentary environment of silicified wood in Tuchengzi Formation of Yanqing was shallow lacustrine deposit in semiarid-semihumid climate,accompanied by volcanic activity.