The geology and coal petrology of a Pleistocene lignite profile at Horemi mine, Megalopolis Basin, Peloponnese (southern Greece)

Abstract

The present study describes the geology, coal petrology and geochemistry of a Pleistocene coal-bearing succession at Horemi mine, Megalopolis Basin (southern Greece). Within a 45-m interval 9 coal seams are exposed, ranging in thickness from 20 cm to 10 m. Reflectances measured on the maceral-type eu-ulminite B range between 0.24 and 0.31% mean R random. This indicates a coalification stage in the transition zone between peat and lignite rank of the A.S.T.M. classification for the Horemi coals. Petrographic studies demonstrated the immature nature of these coals and the low degree of compaction during diagenesis. Compositionally, the Horemi coals are characterized by low amounts (5.3 vol%) of the inertinite group macerals, moderate amounts (11.9 vol%) of liptinite group macerals and very high amounts (82.8 vol%) of the huminite group macerals (on average and mineral-matter-free basis). Within the latter group densinite, attrinite and ulminite make up the bulk of the samples. Results from proximate and ultimate analysis gave on average 53.7% bed moisture, and 37.3% ash, 45.8% volatiles and 18.1% fixed carbon (d.b). Calorific value determinations vary between 1805 and 5470 kcal/kg. Mineral matter is high, varying within the range 20.8–51.9 vol%. Identifiable mineral constituents include quartz, anhydrite, illite, feldspars, calcite, gypsum and chlorite, and minor amounts of barite and pyrite. Reflectances obtained from ulminite were found to be negatively correlated with volatile matter, whereas there is a trend for a positive correlation of them with calorific values.