Łupki antrakozjowe niecki śródsudeckiej w świetle wskaźników geochemii organicznej – wstępne wyniki analizy bituminów
Abstract
The Anthracosia Shales from the Intra-Sudetic Basin in the light of organic geochemistry proxies – preliminary results of bitumen study.
A b s t r a c t. The lacustrine Anthracosia Shales of the Intra-Sudetic Basin are sediments that have become the subject of interest due to their dark colour, indicating an increased content of dispersed organic matter. The published data concern the characteristics of macerals, vitrinite reflectance, the results of Rock-Eval pyrolysis and the results of palynological tests. The above studies were supplemented with the current analysis of the extracted bitumens. The results of the distribution of n-alkanes in the Anthracosia Shales corresponds with the results of macerals and palynology. The dominance of short-chain homologues indicates the microbial-algal origin of the organic matter. Some contribution of terrestrial organic matter is not excluded. Three lithofacies intervals differing geochemically have been distinguished: I – dark grey calcareous claystones rich in aliphatic compounds of microbial and algal origin; II – grey mudstones with siderites containing a lower amount of aliphatic compounds in favour of polar and aromatic compounds; III – weakly calcareous mudstones and sandstones, poor in terrestrial organic matter. The distribution of n alkanes, phenanthrene and methylphenanthrenes (CPI, MPI, MPR, PP1) shown that the maturity of the organic substance is within the oil window. This is further supported by the Rock-Eval data and vitrinite reflectance values.
A b s t r a c t. The lacustrine Anthracosia Shales of the Intra-Sudetic Basin are sediments that have become the subject of interest due to their dark colour, indicating an increased content of dispersed organic matter. The published data concern the characteristics of macerals, vitrinite reflectance, the results of Rock-Eval pyrolysis and the results of palynological tests. The above studies were supplemented with the current analysis of the extracted bitumens. The results of the distribution of n-alkanes in the Anthracosia Shales corresponds with the results of macerals and palynology. The dominance of short-chain homologues indicates the microbial-algal origin of the organic matter. Some contribution of terrestrial organic matter is not excluded. Three lithofacies intervals differing geochemically have been distinguished: I – dark grey calcareous claystones rich in aliphatic compounds of microbial and algal origin; II – grey mudstones with siderites containing a lower amount of aliphatic compounds in favour of polar and aromatic compounds; III – weakly calcareous mudstones and sandstones, poor in terrestrial organic matter. The distribution of n alkanes, phenanthrene and methylphenanthrenes (CPI, MPI, MPR, PP1) shown that the maturity of the organic substance is within the oil window. This is further supported by the Rock-Eval data and vitrinite reflectance values.