Synoptic palaeogeography of the Northeast Atlantic Seaway: late Permian to Cretaceous

Abstract

Abstract The NE Atlantic rift system was a key element in marine connectivity between the northern (Boreal) and southern (Tethyan) marine realms. Palaeogeographic summary maps in this account emphasize the exploitation of pre-existing basement grain on a regional scale, particularly that of the Caledonian Orogen, in the development of the Mesozoic linked rift systems. Also emphasized are the importance of extension across the rift system during successive tectonic episodes and, as implied by restoration of the stretching, the narrowness of the proto-North Atlantic seaway in the Late Permian — Early Mesozoic. The palaeogeographic maps document a sequence of tectonic events leading to the break-up of Pangea. Block-faulting in the mid-Permian enabled marine conditions to penetrate southwards from the Boreal Sea to the Zechstein and Bakevillia Seas of NW Europe, although no link with the Tethyan realm can be documented. The Triassic was characterized by intense differential movement and sediment accumulation. Sporadic marine ingressions took place into the NE Atlantic and North Sea basins. However, no throughgoing connection between marine tracts in the Barents Sea and Tethys was established until the Early Jurassic, when a series of transgressions brought widespread marine conditions and faunal unification between north and south. In the Middle Jurassic, regional uplift in the central North Sea, and probably in the NE Atlantic rift system, ran counter to an overall transgressive regime, suggested by regional sea-level curves and by overstepping of the East Greenland and Mid-Norwegian basin margins. These restrictions re-established acute provinciality between the Boreal and Tethyan realms. Marine connections were restored by intense rifting and transgression in the Late Jurassic, but the evolution of a complex seaway with major land barriers in the earliest Cretaceous saw a return of marine provinciality. Transgressions associated with probable ocean floor development to the southwest (Rockall Trough, Hatton-Rockall Basin) and northwest (Canada Basin) of the study area in the Albian and Late Cretaceous finally established an open seaway through the NE Atlantic rift. Massive subsidence in the Faeroes Trough and Mid-Norwegian basins, and dextral shear along the Barents Sea margin, were precursors to final crustal separation in the Early Tertiary.