Characteristic biomarkers in organic matter from three Zechstein (Late Permian) carbonate units
published: Sep 1, 2016
ArtNo. ESP171016702008, Price: 29.00 €
Biomarker evidence suggests that organic matter (OM) in the Late Permian (Zechstein) Southern Permian Basin (SPB) was characterised by lipid sources reflecting the complexity of marine settings and variations in the palaeowater-column redox state. This is particularly the case with regards to the deposition of the carbonate rocks in Lopingian Zechstein cycles 1, 2 and 3 (Z1 Zechstein Limestone, Z2 Main Dolomite, Z3 Platy Dolomite). Additional biomarker data obtained from Zechstein Limestone and Platy Dolomite basinal facies and integration of published Main Dolomite biomarker data allowed an evaluation of the OM source and redox conditions in these carbonate units. This approach revealed characteristic lipid biomarkers unique for each carbonate formation. Specifically, OM in the Zechstein Limestone is characterised by the presence of archaeal 2,6,10,15,19-pentamethylicosane detected in marginal facies. The Main Dolomite contains isorenieratene and chlorobactene derivatives indicating the former presence of green sulphur bacteria, and bacterial 28,30-bisnorhopane, both found in lower slope to shallow basin facies. High concentrations of pentakishomohopanes and predominance of C34hopanes over C33 and C35homologues are also characteristic of Main Dolomite facies. Increased abundances of C23and C 24terpenoids detected in Main Dolomite basinal facies can also be regarded as important distinctive biomarkers. The Platy Dolomite has a high content of bacterial C29and C 3017β(H),21α(H) hopanes, an unknown C 31triterpane, and an immature pattern of desmethyl steranes detected in platform facies. The identification of these biomarkers will help to evaluate the origin of potentially migrating or already trapped oil in the Zechstein carbonate strata.