Biomarker features of sabkha-associated microbialites from the Zechstein Platy Dolomite (Upper Permian) of northern Poland

The Zechstein (Upper Permian) Platy Dolomite deposits of the Łeba Elevation (N Poland) formed a shallow water carbonate platform developed in hypersaline peritidal arid system dominated by various microbialite lithofacies. Extractable hydrocarbons from the Platy Dolomite microbialite carbonate deposits from the Łeba Elevation (N Poland) show a predominance of even carbon numbered n-alkanes within the range of C20 to C30 (maximum at n-C24). Hopanes are represented by the 17α(H), 21β(H) and 17β(H), 21α(H) series, with carbon numbers ranging from C29 to C35 plus minor amounts of 17α(H)-22, 29, 30-trisnorhopane, 17β(H)-22, 29, 30-trisnorhopane and gammacerane. Despite the absence of 17β(H), 21β(H) hopanes, an anomalously high content of C29–C30 17β(H), 21α(H) hopanes and the extent of epimerization at C-22 below the value of the equilibrium value for the C31–C35 compounds of both 17α(H), 21β(H) and 17β(H), 21α(H) hopane series indicate the immaturity of the organic matter. Organic geochemistry data confirm that the organic matter originated from degraded cyanobacterial and bacterial remains.