Rare earth element geochemistry of coals from the Mazino Coal Mine, Tabas Coalfield, Iran

The Mazino deposit with 650 Mt estimated reserves is the largest steam coal deposit in Iran. The concentrations and distribution patterns of rare earth elements (REEs) in coal, coaly shale and siltstone samples from the Mazino mine were studied by inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of aREEs in coal samples range from 16.4 to 184 ppm with average of 88.9 ppm. There are two types of distribution patterns of aREEs in the coal samples. One type, in the part of the section has slightly higher aREE concentrations and (Light REEs)/(Heavy REEs) ratio with a flat normalized REEs pattern; the other is enriched in HREEs relative to LREEs. The positive correlation and vertical variations of aREEs mainly follow those of the coal ash yield, and the SiO2, Al2O3, and K2O percentage in the coal, suggesting that the aREEs concentrations in coal are mainly controlled by input of land-derived detritus. There is an overall increasing trend in aREEs content upward through the coal seam.