3.2. Fjord sampling and definition of sub-environments
Two field campaigns were conducted in June 2016 and October 2016 to sample the fjord sediments. In total, we use a set of 15 sediment cores, which sampled the upper 30 to 200 cm of recent seabed sediment. These cores were located across all sub-environments of the fjord’s seabed, including the sandy channel floor and lobe, as well as the muddy overbank and distal flat basin (Fig. 3). We have few constraints on the characteristics/extent of turbidity current overbank flows, so we infer the overbank’s external limit as the base of the fjord walls (red outlined area in Fig. 3). We note that sediment cores from these overbank areas are located relatively close to the sandy channel. A sediment core at the end of the fjord (650 m water depth) is used to characterize the OC composition for the entire distal flat basin (core 15; light blue outlined area in Fig. 3). We have no samples on the steep fjord sidewalls; hence these areas are not included in our OC analyses.
Visual logging identified sandy and muddy facies within the sediment cores (Fig. 3e, f). A total of 99 sub-samples were collected from the fjord sediment cores, to ensure representative sampling of each of the facies that were present in the channel floor, overbanks, lobe and distal flat basin. All samples were analyzed for carbon geochemistry, as described below.