Turbidites in the Eocene of Spitsbergen: Can they tell us something about the Sørvestsnaget Basin?

• Main Authors: Grundvåg, Sten-Andreas, Helland-Hansen, William, Safronova, Polina
• Format: Conference Object
• Language: English
• Published: 2017
• Subjects: Svalbard; Sørvestsnaget; Spitsbergen
• Online Access: https://hdl.handle.net/10037/30841

The Eocene of Spitsbergen, Svalbard, has received considerable attention in the literature because of its spectacular seismic-scale clinforms exposed along many fiords and valleys. High quality outcrops enables downdip tracing of facies belts from the proximal shelf through the shelf-edge and down-slope into the basin floor. Previous publications particularly focused on the shelf-edge to slope segment of the clinoforms and demonstrated how shelf-edge deltas played a major role in sediment transport into the deeper parts of the basin. Thick, sandstone-dominated turbidite lobes occur in the toeset of some clinoforms. Few studies have investigated in detail these turbidite deposits. By combining outcrop and core data from central Spitsbergen, this study investigates the sedimentary processes that formed the turbidite lobes. Our previous studies shows that turbidite lobes occur in two basin-wide NW–SE-oriented zones. In areas with multiple stacked turbidite lobes, the lobes show an offset stacking pattern. Internally, lobes shows proximal to distal (or axis to off-axis) facies trends with beds thinning distally, as well as vertical facies trends characterized by an upwards increase in bed thickness and degree of amalgamation. These trends together indicate that the turbidite lobes are progradationally stacked, reflecting the overall progradational nature of the accompanying clinform system. At bed-to-bed scale, many of the turbidites deviates from the classical Bouma-type facies pattern typical of deposition from surge-type, low-density turbidity currents. Many beds instead show a two- or three-fold-division typical of hybrid sediment gravity flows. These beds have a lower sandstone-dominated turbidite division succeeded by a clast- and mudstone-rich debrite division (see inset photo). Some beds also have an upper thinbedded turbidite division deposited from the dilute tail of the flow. The two-folded bed division indicate that some turbidity flows transformed into slurry flows or debris flows on their way to their ...