Contourite deposits reveal late Paleocene to early Eocene deepwater circulation in the Norwegian-Greenland Sea

Abstract The history of deep-water circulation between the Norwegian-Greenland Sea (NGS) and the North Atlantic Ocean is poorly constrained for the Paleocene to early Eocene—a period characterized by prolonged rifting and subsequent seafloor spreading. We integrate seismic stratigraphy and biostratigraphy from the NGS to demonstrate several phases of bottom-current erosion and deposition, indicating deepwater circulation before and during breakup. A confined contourite depositional system developed in the central NGS during the late Paleocene. This phase was followed by an ~2 m.y. period of reduced circulation in the earliest Eocene, when a volcanic landmass restricted the marine connections to the North Atlantic. Renewed bottom-current activity in the earliest Eocene led to widespread contourite deposition along an ~350 km stretch of the western NGS. This circulation system consisted of a southward-flowing western branch and a northward-flowing eastern branch, resembling Neogene to modern circulation patterns. Our results indicate that bottom-current activity predates previous records of contourite drift deposits in the NGS, and that the timing and distribution of contourite deposition were strongly controlled by the evolving basin configuration. We link early Eocene deepwater circulation to the formation of new seaways during breakup and seafloor spreading, rather than bathymetric changes of distant ocean gateways. These results have important implications for basin segmentation during the rift-to-drift transition and for reconstructing early deepwater exchange between the NGS and the North Atlantic.