Contrasting Neogene–Quaternary continental margin evolution offshore mid-north Norway: Implications for source-to-sink systems

The Neogene–Quaternary development of the ∼700 km long mid-Norwegian and Lofoten–Vesterålen continental margin is reconstructed using a dense grid of 2D seismic data and exploration wellbores. Overall, widespread ocean current-controlled contourite drifts built up along the whole margin segment from the mid-Miocene onwards (c. 11 Ma, Kai Formation). The onset (c. 8.8 Ma) of a large inner shelf progradation (Molo Formation) was, however, restricted to the southern part of the study area, the inner mid-Norwegian shelf. In the Quaternary (c. 2.7 Ma), grounded ice sheets repeatedly brought large sediment volumes (Naust Formation) to the shelf beyond the Molo Formation. A similar build-out is less pronounced further north, where contourite drift growth instead continued and resulted in build-up of the Lofoten and Vesterålen drifts. In contrast, the drifts of the southern part of the study area occur for the most part stratigraphically below, interbedded with and distal to the progradational Molo and Naust deposits. The study area exemplifies pronounced variability in Neogene–Quaternary continental margin growth. The wide and gently dipping mid-Norwegian margin facilitated coastal and shelf progradation related to fluvial and glacial processes, while the narrow and steep Lofoten–Vesterålen margin received little input from these sources although exposed to the same paleoclimate. Instead, erosion of canyons promoted downslope reworking across the slope and into the deep basins. This low sediment input is interpreted to be controlled by the alpine relief in the north resulting in a small source area and thus low fluvial and glacial sediment input. To the south, hinterland relief allowed for a much larger fluvial and later, glacial source area. Both margin segments were also influenced by contour currents throughout the studied period. We emphasize their importance for understanding the role of erosion and deposition in source-to-sink systems, and thus the need for these processes to be integrated within source-to-sink model

A multi-source-to-sink system in a dynamic plate tectonic setting: the Cenozoic of the Barents Sea, Norwegian Arctic

Abstract of an oral presentation at the 61st British Sedimentological Resarch Group Annual Meeting, Southampton, 6-8 December 2022.When multiple source areas are located on a continuously moving plate margin relative to a sink, the signal propagation in the source-to-sink system may vary significantly in time and space. How fast and severe the impact of tectonics and climate is on sediment erosiontransfer-deposition in this dynamic setting is still not well understood. Similarly, how do we quantify the relative sediment contribution from each source area? Here, we use a forward stratigraphic modelling technique to constrain key controlling parameters in basin filling in relation to the Cenozoic successions of the Barents Sea in the Norwegian Arctic. The Cenozoic evolution of the Barents Sea shelf is strongly linked to the breakup between the Greenland and the Eurasian plates at c. 55 Ma, which led to the development of highs and basins along the margins of the Barents Sea. This configuration resulted in the deposition of progradational wedges and submarine fans (c. 40 Ma) in the Sørvestsnaget Basin. Subsequent plate reorganization caused a major shelf uplift (c. 33 Ma) and opening of the Fram Strait (c. 17 Ma) and affected the sedimentary processes and deposits in the sink (including contourites) now observable in seismic and borehole data. Moreover, Cenozoic successions were deposited under different extreme climate settings ranging from the Paleocene-Eocene Thermal Maximum (PETM) to icehouse conditions during the Quaternary glaciations (c. <2.7 Ma). A major increase in sediment supply resulting from glacial erosion is reflected in the deposition of a series of trough mouth fans along the continental margin. We present preliminary results of an ongoing project modelling this source-to-sink system, and discuss what factors control sediment erosion, transfer, and basin filling

Underexplored continental shelf gateways: timing, mechanisms and role of SW Barents Sea Gateway, Norwegian Arctic

Abstract of presentation given at the OCEANIC GATEWAYS: MODERN AND ANCIENT ANALOGUES AND THEIR CONCEPTUAL AND ECONOMIC IMPLICATIONS Conference, organised by The Geological Society of London, London, 23-25 November 2022.Ocean gateways connecting ocean basins are crucial for water and heat circulation, which influence global temperature, climate evolution and sediment distribution. While deep-water gateways have been a major research focus by the community, very little attention has been drawn to shallower gateways located on the continental shelves, where such circulation also takes place. In this study, we investigate the evolution of a shallow gateway in SW Barents Sea that presently connects NE Atlantic and Arctic oceans. This gateway contributes to about half of the Atlantic–Arctic water exchange, whereas the other half is occurring through the deeper Fram Strait Gateway. When and how this SW Barents Sea Gateway formed are debated and still poorly understood. Outcomes from this study will thus be relevant for regional and global models of ocean circulation. Moreover, this study will contribute to climate evolution models over longer timescale in a climate sensitive region where an Arctic amplification of warming is presently seen

Paleobathymetric reconstructions of the SW Barents Seaway and their implications for Atlantic–Arctic ocean circulation

Unravelling past, large-scale ocean circulation patterns is crucial for deciphering the longterm global paleoclimate. Here we apply numerical modelling to reconstruct the detailed paleobathymetry-topography of the southwestern inlet of the Barents Seaway that presently connects the Atlantic and Arctic oceans. Subaerial topography was likely enough to block Atlantic Water from entering the Barents Seaway in the earliest Eocene (c. 55 Ma). The water may have entered in the middle Eocene (c. 47 Ma) as observed from major basin subsidence, but paleotopographic highs to the east may have hindered connections between the two oceans. From the Oligocene (c. 33 Ma) until the onset of the Quaternary (c. 2.7 Ma), basin shallowing and regional shelf uplift blocked Atlantic Water from entering the Barents Seaway. Our results imply that the Fram Strait remained the sole gateway for Atlantic Water into the Arctic Ocean since its opening in the Miocene until the Quaternary

Sediment source-to-sink analysis in the Norwegian Arctic

Abstract of guest lecture in the Research Seminar Series at Royal Holloway University of London, 1 December 2022

A time-transgressive perspective of glacial erosion and meltwater beneath the Eurasian ice sheet

Academic presentation at The 4th International PalaeoArc Conference, Akureyri, Iceland, 27.08.23 - 30.08.23. https://www.arcus.org/events/arctic-calendar/34282.The efficacy and controls governing glacial erosion over geological timescales are intricately linked yet remain poorly understood and contended. By assimilating geophysical data with modelling of the Eurasian Ice Sheet - the third largest Quaternary ice mass that spanned 49°N - 82°N - we decipher its erosional footprint during the last ~110 ka glacial cycle. Our results demonstrate extreme spatiotemporal heterogeneity in erosion with short-term rates ranging from 0 - 5 mm a-1 , and a net volume equating to ~130,000 km3 of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. A notable signature of this thermomechanically regulated erosional footprint is an increase in the intensity of erosion across upland areas of Fennoscandia and within troughs in the Barents Sea during the last deglaciation compared to the long-term mean. New meltwater landforms mapped from multibeam bathymetry data collected in the Central Barents Sea capture insight into the evolving nature of the subglacial environment of the Barents Sea ice sheet as it thinned and collapsed; the apparent abundance of basal meltwater, which we interpret was increasingly being supplemented by inputs from supraglacial melting, likely contributed to elevated erosion of the sedimentary substrate and the mobilisation of subglacial sediments during the latter stages of deglaciatio