Genetic classification of Polish lignite deposits: A review

Poland is one of the largest lignite producers, not only in the European Union but also in the world. The majority of lignite deposits that have economic value are of Early and Middle Miocene age; however, the Early-Oligocene lignite seam, and the so-called accompanying lignite seams of Middle Miocene age, may also occasionally be important for the mining industry. Therefore, five main and two accompanying lignite seams are described among the Oligocene-Miocene sediments in central-western Poland. These seams are present in sixty-nine deposits, which are taken into consideration in this contribution. Polish lignite deposits can be classified genetically. Thus, they are divided into four main types (epeirogenic, tectonic, karstic and glaciotectonic), which contain seven subtypes (sheet, lenticular, grabens, salt-karst, carbonate-karst, fold, thrust/sliced) of lignite deposits. The vast majority of lignite resources represent the tectonic and/or epeirogenic type of deposits. Almost 100% of lignite production in Poland, that is, about 63-66 Mt. per year, is exploited from them. On the other hand, the most deformed syn- and/or post-depositionally are two deposits, the Rogóźno and Sieniawa ones, which belong to the salt-karst type (salt-karst subtype) and the glaciotectonic type (fold and thrust/sliced subtypes) of lignite deposits, respectively. Finally, knowledge about the genesis of lignite deposits can be useful during their exploration and exploitation. This allows for proper planning of geological prospecting of the deposits and the use of a better method of lignite mining.