Raman and cathodoluminescence spectroscopic investigations on Permian fossil wood from Chemnitz--a contribution to the study of the permineralisation process.
Raman and cathodoluminescence spectroscopic investigations on Permian fossil wood from Chemnitz--a contribution to the study of the permineralisation process.
复制标题
对来自开姆尼茨的二叠纪化石木材的拉曼和阴极发光光谱研究——对全矿化过程研究的贡献。
DOI：
10.1016/j.saa.2003.12.045
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
G. Marx
中科院分区：
文献类型：
--
作者：
K. Witke;J. Götze;R. Roessler;D. Dietrich;G. Marx
不同三维保存的植物化石样本（Medullosa sp.，杜氏藻属，（Calamodendron striatum，Psaronius sp.）对采自切姆尼茨早二叠世石化林的10个化石的化学组成和结构顺序进行了研究。拉曼光谱和阴极发光显微镜被证明是这样的调查的有力工具。开姆尼茨-希尔伯斯多夫硅化木的细胞壁阴极射线发光（CL）一般为黄色，而细胞腔的阴极射线发光只有微弱的黄棕色。通过时间分辨阴极发光光谱，热液成因的次生矿化被确认。后者由细胞壁处的短寿命蓝色CL显示，熄灭黄色信号。因此，在初次硅化步骤之后，由水热过程引发的二次矿化步骤似乎在可能略高的温度下发生。由此产生的二氧化硅基质由显晶和微晶α-石英以及微晶莫甘石组成，两者均部分与氧化铁缔合。Dabriylon sp.是α-石英和氟石平行渗透作用的一个突出例子，这在切姆尼茨石化森林中非常突出。该样品上的CL显示出平行的硅化和氟化，随后是铁氧化物的渗透。渗透样品显示原始有机残留物的百分比非常低。例如，种子蕨Medullosa显示出分散的碳，这主要限于典型的星形维管束的中心。拉曼光谱表明这些碳质颗粒具有无烟煤结构。为了验证实验结果，对不同煤阶的煤样，特别是不同地质时代和不同产地的无烟煤，进行了拉曼光谱研究。维管束的剩余髓为白色，由α-石英和莫甘石组成，而周围的管胞显示白色和红色部分。红色部分主要见于射线中，在α-石英和莫干石的SiO2多晶型物中还含有α-Fe 2 O3和Fe 3 O 4。有时，铁氧化物可能占主导地位的渗透过程中，不同部分的样品的峰值强度表明。
Samples of different three-dimensionally preserved fossil plants (Medullosa sp., Dadoxylon sp., Calamodendron striatum, Psaronius sp.) from the Lower Permian petrified forest of Chemnitz were examined with regard to their chemical composition and structural order. Raman spectroscopy and cathodoluminescence microscopy are shown to be powerful tools for such investigations. Silicified wood from Chemnitz–Hilbersdorf generally shows yellow cathodoluminescence (CL) of the cell walls and only weak yellow-brownish CL of the cell lumina. By time-resolved cathodoluminescence spectroscopy, a secondary mineralisation of hydrothermal origin was recognized. The latter is shown by short-lived blue CL at the cell walls extinguishing the yellow signal. Therefore, after the primary silicification step a secondary mineralisation step initiated by hydrothermal processes, seems to have taken place at probably slightly higher temperatures. The resulting silica matrix consists of phanerocrystalline and microcrystalline α-quartz as well as microcrystalline moganite, both partially associated with iron oxides. Dadoxylon sp. is a prominent example for parallel permineralisation by α-quartz and fluorspar, which is outstanding for the Chemnitz Petrified Forest. CL on this samples shows parallel silicification and fluoritisation, followed by infiltration of iron oxides. Permineralised samples show very low percentage of original organic remains. The seed fern Medullosa, for example, shows dispersed carbon, which is mainly restricted to the centres of the typical star-shaped vascular bundles. Raman spectroscopy revealed that these carbonaceous particles are of an anthracite structure. For experimental confirmation coal samples of different rank, especially anthracite from different geological times and localities, were studied by means of Raman spectroscopy. The remaining pith of the vascular bundles is white-coloured and consists of α-quartz and moganite, whereas surrounding tracheides exhibit white and reddish coloured parts. The reddish parts, mainly found in the rays, additionally contain α-Fe2O3and Fe3O4among the SiO2polymorphs of α-quartz and moganite. Sometimes iron oxides could have dominated permineralisation processes as the peak intensities of distinct parts of the samples suggest.