Petrographical, Palynological, and Sedimentological Aspects Regarding the Genesis of Palaeogene Lignites Near Alexandroupolis, Thrace, Greece

Several minor lignite deposits of Palaeogene (Eocene to Oligocene) age occur in the vicinity of Alexandroupolis, Thrace, northern Greece. A few rather thin seams were mined in the past by small private operations for local use. Coal samples have been collected from old mine dumps and outcrops around abandoned mine posts to be studied by means of maceral analysis at high magnification. The groundwater and vegetation index are calculated from the maceral composition and used to draw conclusions concerning the environment of deposition. In addition, block samples of coal cut perpendicular to bedding were studied at intermediate magnification and under fluorescence thus revealing some interesting bedding features as well as well-preserved plant organisms. The coals are characteristically finely laminated and highly gelified.

Palynological preparations have thus far yielded only poorly preserved palynomorph assemblages rather low in diversity and dominated by fern spores. This fern dominance is rather unusual; however, it is compatible with the occurrence of fertile fern fronds observed in petrographic coal sections.

Accompanying clastic sediments exhibit cyclic fining-upward sequences at a scale averaging about 1 m in vertical extent. Grain sizes range from small gravel to clay and silt. In some cases, siltstones in the roof of coal seams include abundant plant fragments showing parallel venation. The evidence presented from various sources suggests a rather unstable fluvial environment and a generally high water table on the flood plain for the formation of these lignites.

Keywords:

• Palaeogene lignites
• Alexandroupolis
• Greece
• palynology
• petrography

Acknowledgments

The help of E. Mavridou (Athens) and Dr. V Bullwinkel (Göttingen) in producing the tables and figures and their assistance in the layout of the article is gratefully acknowledged.