Petrographic Characteristics of the Kardia Lignites (Core KT6A-3), Ptolemais Basin (Greece)

The aim of this study is to provide useful coal-petrographic data, which will further help the characterization, exploitation, and utilization of the Kardia lignite deposit and also initially to access the depositional conditions mainly in terms of water table level and subsidence rate of the fen substrate. Ash contents, as well as the C, H, N, O, and S were determined in nine lignite samples from core KT6A-3. The ash contents (750°C) of the studied lignite seams range among 14–37% (on dry basis). Contents of C, H, N, and O have values between 34–52%, 2.5–4.2%, 0.8–2%, and 21–30.6%, respectively. Sulfur does not exceed 1.2%. Huminite group dominates with values between 84–99 vol%, mmf. All samples display a distinct prevalence in detrohuminite (up to 82 vol%) with attrinite being most abundant. Liptinite and inertinite macerals have low contents, which do not exceed 8% and 12%, respectively. The Kardia lignites are medium to very low-grade coals. They formed in fens under limnotelmatic regime and originated from herbaceous vegetation. During peat deposition, conditions were well moist, intense reducing, and favored increased bacterial activity. The ratio of plant growth and peat accumulation versus rise of water table due to the subsidence rate was not well balanced. The petrographical composition of the Kardia lignites is related either to a long residence time of the organic matter in the acrotelm or to an herbaceous vegetation origin.

Keywords:

• Kardia lignite
• macerals
• facies diagrams
• organic petrography
• Greece

Acknowledgments

Assistance provided by members of the Drilling and Exploration Branch of the Public Power Corporation (PPC), particularly by geologists V. Makris, D. Siskos, N. Tsakiris, A. Nikou, and P. Kalaitzopoulos is gratefully acknowledged.