Significant Occurrences of REE in Tertiary Sequence of East Jaintia Hills, Meghalaya, India

Considering the importance of REE resources, that are used in several high-technology areas, the present study aims to assess the potentiality of REE in the sedimentary sequence of Shella and Kopili formations (350m and 60m respectively) in East Jaintia Hills district, Meghalaya. A well-developed sedimentary sequence of Shella and Kopili formations of Jaintia Group, middle to upper Eocene age, are exposed in Jaintia Hills. The semi-quantitative (SEM-EDX) analysis of black shale and carbonaceous shale indicate the presence of monazite and xenotime phases. The REE+Y concentration ranges from 77.1 to 1168.7 ppm (avg. 295 ppm). The LREEs (La-Eu) ranges from 55 to 782 ppm (avg. 211.3 ppm), whereas HREEs (Gd-Lu+Y) ranges from 18.8 to 385.9 ppm (avg. 83.7 ppm). Nd ranges from 15.8 to 229.3 ppm (avg. 66.1 ppm). The REE+Y concentration in black shale yields 1168.7 ppm. Further, REE in two coal samples yields 111.6 and 63.2 ppm. REE shows a strong positive correlation with Zr, Y, U and Th, weak positive correlation with V and weak negative correlation with Sc. The REE concentrations in coal samples are relatively higher than previously reported REE concentrations and are comparable with worldwide average values of REE. The REE concentrations in black shale and coal are significant for further exploration.