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.