Late Ryazanian black shales in the Southern North Sea Basin and their lithostratigraphical significance

Abstract

SUMMARY The basal beds of the Speeton Clay Formation in Yorkshire and BGS Offshore Borehole 81/43, Beds E and D8 of late Ryazanian age, are in poorly fossiliferous, carbonate-free, organic-rich Kimmeridge Clay type facies. Above Bed D8 there is a rapid transition to carbonate-rich sediments with a lower organic carbon content and increasingly diverse faunal and palynofloral assemblages. In the Northern and Central North Sea basins similar coeval facies changes are represented by the Kimmeridge Clay Formation/Valhall Formation boundary.