Abundance of Sulphur in Paleogene coals of North-East India and Its Paleo-environmental Implications

Abstract

The present paper entails the occurrence and distribution of different forms of sulphur in Paleogene coals of north-eastern India. All the coal seams present in the north-eastern region of India are characterized by the presence of high sulphur with total sulphur content ranging from 3 to 7%. Among all the forms of sulphur recognised, organic sulphur is dominant. The total sulphur content originated in the Platform area for Eocene coal under stable shelf condition vary from 4.20 % to 6.01 % for Jaintia Hills, from 2.78 % to 4.01 % for Khasi Hills and from 1.90 % to 3.00 % for Garo Hills, whereas Oligocene coal evolved under the foredeep basin have total sulphur ranging in from 2.90 % and 6.60 %. In the Eocene coals, there is a distinct lateral and vertical variation of sulphur i.e., sulphur content increases from the bottom to the top seam and also from western side of Meghalaya to the eastern side. This lateral variation of sulphur was because of the more marine nature of the Eastern Meghalaya than the Western Meghalaya. Both Eocene and Oligocene coals have been derived from seawater as evidenced by the presence of pyritic form of sulphur. Study of forms of sulphur also suggests that the deposition of the coals in a different part of the region was influenced by roof strata, peat-forming plant communities, tectonic uplifting, and marine or freshwater incursion.