Early Palaeogene tectonics and sedimentation in the Central North Sea

The early Palaeogene deposits of the Central North Sea have been divided by Stewart into ten depositional units, on the basis of seismic stratigraphy. These are interpreted as the products of variations in relative sea level. The units may be traced from the shelf into the basin using wireline log markers correlated within a biostratigraphic framework. These are interpreted as the signature of transgressive maxima when basinal clastic supply was at a minimum. The attitude of coal or lignite beds within the shelfal areas can be used to demonstrate a period of Palaeogene net uplift, followed by tilting and sinking of the shelf-edge and basinal areas during the later depositional episodes. Other than by a mechanism of load-induced differential compaction around buried or partially buried Mesozoic features no significiant rejuvenation of Mesozoic faults can be demonstrated. The area of uplift extended at least as far as the western limit of the Beauly Formation. The products of Stewart’s depositional episodes vary depending on the tectonic activity. During the uplift phase, thick massive basinal fans were deposited and little or no shelfal deposits are preserved. During the tilting/sinking phase thick progradational wedges were deposited, and basinal deposition was largely confined to shales with relatively small local sand systems.