The fossil floras of Kachchh. V - Nature, composition and rank (Maturation) of Mesozoic coals

Abstract

The petrographic and rank studies of Mesozoic coals have been carried out from Trambau, Rukmawati, Chawad and Guneri areas of Kachchh Basin. The vitrinite group of macerals and mineral matter form the dominant constituents of these coals and on the basis of their quantitative representation, three coal types, viz. (i) vitrinite/vitrite dominant type, (ii) mineral matter/carbominerite dominant type, and (iii) intermediate type have been suggested. The richness of mineral matter with the presence of pyrite and Sulphur in appreciable amount has been related with the deposition of the vegetal matter by shallow rapidly shifting channels of delta regime under the possible influence of marine conditions. The reflectance (rank) study has indicated a progressive increase in the maturation of coal towards the western part of the basin. This trend of maturation seems to have been resulted due to the intense tectonic activity in the north-western parts of the area. The rank study of coals also indicates that some of the sediments in the area have attained to a level of organic maturity corresponding to the oil generation zone.