Annual resolution analysis of a SW-France stalagmite by X-ray synchrotron microprobe analysis

A sample of stalagmite from Grotte de Villars, Dordogne, France was analyzed by the use of X-ray synchrotron microprobe in LURE, Orsay, France. Together with the signal of Ca, the main element, much weaker but clear signals of Sr, Fe, Zn and Pb were registered. The X-ray scattered radiation was applied for recognition of the annual zones in the stalagmite structure in parallel with the gray scale morphology from the optical microscope. The elemental scans were superimposed on the optical image of the sample. It was established that places corresponding to dark locations on the annual rings were narrower, composed of less porous matter and had much greater contents of iron and zinc and elevated ratio of Sr/Ca. In the supplementary electron microprobe measurements, the elevated amounts of lighter elements, Si and Mg were found in the same locations. These results will allow a very accurate study of stalagmite elemental composition which is of first importance for paleoclimatic studies from speleothems.