CHARACTERIZATION OF THE KEROGEN FRACTION OF ARNSBERGIAN (LATE MISSISSIPPIAN, SERPUKHOVIAN) MUDSTONES IN THE UK PENNINE BASIN
Here we present palynological and geochemical results of the Edale Shales (Mississippian, Serpukhovian) from two boreholes: the Carsington Dam Reconstruction Borehole C3, located in the Widmerpool Gulf (Derbyshire) and the Karenight 1 Borehole drilled near the southern edge of the Edale Gulf (Derbyshire). Both depocentres were part of the Pennine Basin which in Mississippian times consisted of a mosaic of small, inter-linked basins formed due to crustal extension north of the Hercynic orogenic zone. Namurian deposits in these basins show a remarkable cyclicity thought to represent responses to eustatically controlled fluctuations of intra-basinal sea-level. The investigated intervals from both boreholes are representative of such a lithological cycle, for which we present new kerogen and Rock-Eval data.
During low stands, the kerogen fraction is characterized by higher levels of phytoclasts and generally lower % Total Organic Carbon (TOC). The high stands are characterized by high levels of granular AOM, higher TOC values, and a higher oil saturation index. This observation suggests that higher granular AOM counts are linked to higher %TOC and may represent intervals of elevated hydrocarbon generative potential. Further palynological investigations are required to clearly delineate the different AOM phases and to understand how these different phases affect hydrocarbon prospectivity. This could then be applied to understanding broader trends in Carboniferous Shales in the U.K. and can be integrated into models identify zones of richer hydrocarbon potential in the highly fragmented Pennine Basin.