Analyses of petrified wood by electron, X-ray and optical microprobes

Samples of petrified wood of different origins were analyzed by the use of the electron microprobe, capillary X-ray fluorescence microprobe, synchrotr on capillary X-ray microprobe and optical microscope, applied in a micropro be manner. The main attention was given to the investigation of the ring st ructure of the petrified wood and the comparison of this with the ring stru cture of the living trees analyzed by much the same methods. The continuous X-radiation, applied in a microprobe manner, the distribution of the gray- scale representation of the secondary electron intensities and the characte ristic X-ray signals, mainly from the light elements, were registered by th e use of the electron microprobe method. The X-ray capillary microprobe det ected the Rayleigh and Compton signals, scattered from microareas of the sa mples, and the characteristic X-ray signals, mainly from the heavier elemen ts. In the synchrotron-based capillary microanalytical measurements, one of the most important results was achieved by the microprobe application of s cattered synchrotron radiation. The emission and scattering results were su pplemented by transmission measurements, where possible. All the methods pr oved to be complementary in the analysis of such periodic structures as tre e rings. Both capillary microprobes were much more efficient in the detecti on of heavy elements and penetrated deeper than the traditional electron mi croprobe. Careful analysis of different signals indicated that some samples of petrified wood in the authors' possession, composed of silica of variab le density, are the chemical negatives of the primordial living wood. This is the first such observation in the literature. Microdiffraction studies o f the samples proved that polycrystalline cr-quartz was the main matrix com ponent of all these samples. The elemental analysis of the petrified wood g ives important indications about the petrification processes. Comparison of the particular ring structure of the petrified wood with the ring structur e of living trees shows great similarities. The widths of rings, density va riations and density maxima are easily readable from the microanalysis of p etrified wood. These parameters potentially can be exploited for the invest igation of the biological, chemical, chronological and climatic information included in the fossilized tissues.