STUDY OF ELEMENT DISTRIBUTIONS IN WEATHERED MARBLE CRUSTS USING LASER-ABLATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

The authentication of marble objects can often be very difficult. As t he presence of a naturally produced weathering crust on an artefact ca n be used as a means of evaluating its antiquity, techniques to invest igate those weathering layers can be very useful in authentication stu dies. In this study, the depth profiles of Mg, Al, Mn, Fe, Zn, Sr, Ba, La and Pb in weathered marble crusts were obtained using laser ablati on inductively coupled plasma mass spectrometry. Ablations were perfor med in the free-running mode with a focused laser. In order to obtain spatial information, the samples were analysed directly without any sa mple preparation. Signal drift was corrected by using the Ca-43 signal as an internal standard. By plotting the ratios obtained as a functio n of the depth below the surface, significant trends were found. In or der to check if quantitative results can be obtained, standards produc ed by adding elemental standard solutions to CaCO3 powder were used. A ccurate concentrations in the sampled micro-spots were obtained for bo th the minor and trace elements in the homogenized synthetic standards and also for the homogeneously distributed minor elements Mg and Sr i n the marble samples.