Mineral Composition of the Zun-Torey Lake(Eastern Siberia)Bottom Sediments Studied by X-Ray Diffraction

摘要

Three methods for determining the mineral and mineral-group content in carbonate-silicate bottom sediments are compared.Two methods are based on the powder X-ray diffraction.The first one uses the processing of diffraction patterns by the Rietveld method.The second one relies on the method of reference intensity ratios(corundum ratios).The third method is based on physical and chemical modeling with the use of data on the elemental composition obtained by XRF and XRD.Thirty core samples of bottom sediments of the Zun-Torey Lake(Eastern Siberia)were analyzed.The contents of the mineral groups(feldspars,quartz,phyllosilicates,carbonates)varied in the range of about 10-40 wt%.The differences between the results obtained by three methods had a standard deviation in the range of 2-9 wt%.The relative standard deviation,as a rule,was less than 30%,therefore such analyses can be considered quantitative.The obtained data has allowed us to estimate the X-ray powder analysis error when determining the content of mineral groups in carbonate-silicate sedimentary rocks in the absence of reference materials.