CAGE – Centre for Arctic Gas Hydrate, Environment and Climate Report Series

CAGE17-1-Leg1 Cruise Report: Water column observation from CTD and water samples west of Prins Karls Forland, Svalbard

Fri, 03 Feb 2023 00:00:00 +0100

From the afternoon of May 15th to the afternoon of May 19th, CAGE-Centre for Arctic Gas Hydrate, Climate and Environment, the Department of Geoscience UiT, the Arctic University of Norway, arranged a scientific cruise to survey offshore Prins Karls Forland, Svalbard to perform CTD measurements and water sampling on R/V “Helmer Hanssen”. The purpose is to study the variations in methane release and its dependence on oceanographic changes. The area has been continuously surveyed for the last three years for methane concentration, and methane consumption by bacteria and other related data. Because of the good weather conditions time allowed survey of the outer part of the shelf west of Prins Karls Forland – the socalled ‘Masox area’. Here three CTD’s were taken and the area surveyed by echosounding (EK60), chirp and multibeam for combined flare survey (EK60) and geological recording of sedimentary environments (chirp and multibeam). A total of 69 CTD (conductivity-temperature-depth) casts were performed with 12 water bottles sampled for each CTD station.

The cruise may be known as: CAGE17_1_leg1

CAGE17-1-Leg 2 cruise report

Mon, 06 Feb 2023 00:00:00 +0100

From the afternoon of May 19^th to the early morning of June 2^nd 2017, CAGE-WP6 at the Department of Geology Uit, the Arctic University of Norway, arranged a scientific cruise aimed at investigating sediment cores and porewater, and water masses, at the western Svalbard margin, Fram Strait, East Greenland Ridge, and Storfjorden Trough, visiting methane seep sites off Vestnesa Ridge, and in Storfjorden Trough on R/V “Helmer Hanssen”. Investigated areas were (in order of visiting sites on the cruise): Prins Karls Forland (PKF) (overlap with ‘leg 1’ 17^th to 19^th of May – see Leg 1 report), southern Yermak Plateau, Vestnesa Ridge, East Greenland Ridge, Storfjorden Trough and Storfjorden.

The scientific sampling was done within the framework of several ongoing projects at the Department of Geology, University of Tromsø: “CAGE – Centre for Arctic Gas Hydrate, Environment and Climate”-WP6: “Methane Release, Ocean Acidification and CO2”. Planned surveys north of Svalbard was abandoned due to extensive sea ice cover and the East Greenland Ridge was surveyed instead. Sea ice over outer Vestnesa prevented surveys there and Storfjorden trough was also completely covered, but the sea ice broke up towards the end of the cruise and thus could be surveyed during the very last part of the cruise.

A total of 15 gravity cores (c. 60 m), and 20 CTD (conductivity-temperature-depth) casts were performed along the western Svalbard margin (Vestnesa and PKF and Yermak). Data were also collected at East Greenland Ridge and in Storfjorden Trough and Storfjorden, brine overflow was detected. The CTD casts and chirp- and multibeam lines from PKF May 17-19^th are reported in the cruise report for Leg 1.

Chirp profiles and multibeam lines were acquired during transits and in surveys (mapping of East Greenland Ridge, moraine systems and basins in Storfjorden Trough, active and inactive pockmarks at Vestnesa Ridge and over and to find potential core sites.

The cruise may be known as: CAGE17_1_leg2

CAGE17-2 Cruise Report: Gas hydrate deposits and methane seepages in Storfjordrenna, Northern Flank of Olga Basin, and West Sentralbanken (Barents Sea): Biogeochemical and biological investigations

Mon, 06 Feb 2023 00:00:00 +0100

The main goal of CAGE 17-2 AMGG cruise was to study the gas-hydrate-bearing system and methane emission off south and east of Spitsbergen in Storfjordrenna and the northern flank of Olga Basin (named here Olga craters) respectively, and in the West Sentralbanken.

We addressed this through a comprehensive scientific program comprising dives with the MISO-Tow Cam adapted to the multicorer frame from UiT-NPI (TowCam/Multicorer, TCM), methane measurements in sediments, water column, and in air, sediment coring (multicorer + gravity corer), water column and sediment biogeochemistry, microbiology, micropaleontology, and bathymetric mapping.

Cruise CAGE 17-2 was also hosting this year’s AMGG research school cruise with masters, PhD and post-doc students participating.

The areas investigated were:

Storfjordrenna, Pingos site (ca 380 m water depth),
Northern Flank of Olga Basin (ca 140 m water depth)
West Sentralbanken (ca 200 m water depth)

We planned the following activities during the CAGE 17-2 cruise:

EM 302 Simrad swath bathymetry mapping to identify seabed morphology

Mapping of flare distributions
CTD stations at different water depths and in different areas for measurements of
ocean water masses characteristics, and
water sampling for water/gas chemistry and microbiology investigations across methane seeps.
TCM surveys (video-camera) to image seabed fluid flow expressions, sites of bacteria mats, crusts and gas bubbles.
Repeated deployments with TCM to sample surficial and shallow sediments with respect to microbiology, geochemistry, biogeochemistry, and micropaleontology.
Gravity corer for studying sediment biogeochemistry, biomarkers, microbiology, and foraminifera.
Scrape sampling to collect rocks and crusts.
Gas Chromatographer (GC) to measure methane concentration in the water and sediment samples.
Flasks Restek, Electro-Polished Miniature Canister (1000 cc) for air samples.

Part of the cruise was supported by NPD, Oljedirektoratet. Special thanks to Rune Mattingsdal, NPD.

The cruise may be known as: CAGE17_2

Cruise CAGE-17-3

Stefan Bünz — Mon, 06 Feb 2023 00:00:00 +0100

The overall goal of cruise CAGE 17-3 is to collect seismic, multibeam and water column data in an area along the northern flank of the Bear island trough and on the W-Svalbard margin. The objectives associated with the overall goal are to better understand the occurrence of gas hydrates and fluid leakage, the source of the gas in these systems, and seafloor expressions of fluid seepage. In order to address these objectives we plan to carry out:

2D and 3D P-Cable seismic and ocean-bottom seismic acquisition over a complex leakage and source-to-sink plumbing system in the Leirdjupet Fault complex in the SW Barents Sea;
Recovery of one of CAGE’s ocean floor observatory from the crater area at the northern flank of the Bear Island Trough;
Repeat of P-Cable 3D seismic acquisition on the eastern segment of the Vestnesa Ridge for time-lapse seismic studies of fluid flow and gas hydrates dynamics;
2D multi-channel seismic for reconnaissance and stratigraphic correlation in the Molloy Ridge area;
Multibeam mapping to fill in gaps and improve resolution of existing data using the upgraded EM302 system on R/V Helmer Hanssen

The cruise may be known as: CAGE17_3

CAGE17-4 Cruise Report: Recovery of observatory and water column survey offshore Svalbard

Bénédicte Ferré — Mon, 06 Feb 2023 00:00:00 +0100

The cruise was conducted from August 3^rd to 5^th 2017 as part of the Centre of Excellence for Arctic Gas Hydrate, Environment and Climate (CAGE) at UiT –The Arctic University of Norway.

The main goal of the cruise was to recover the observatory K-Lander 2 deployed in October 2016 offshore Svalbard, at the same location where OS2 was deployed in June 2015 and recovered in May 2016.

The present cruise also aimed at continuing the water samples and CTD survey on the shallow shelf and the shelf edge presenting extensive flares western Svalbard. The addressed scientific topics include quantification of methane concentration in the water column, temperature and salinity (via CTD casts), echosounder and multibeam signals and current (amplitude and direction).

The cruise may be known as: CAGE17_4

CAGE17-5 Cruise Report: Marine Geophysical Cruise to the Yermak Plateau and western Svalbard continental margin

Andreassen Karin — Fri, 03 Feb 2023 00:00:00 +0100

The cruise was a part of the Centre of Excellence for Gas Hydrate, Environment and Climate (CAGE) at UiT ‐ The Arctic University of Norway.

The cruise had the following scientific objectives:

Geomorphic mapping of seafloor features at the Yermak Plateau, as far north as possible aiming at identifying ice flow orientations.
Improve the seismic stratigraphy along the western Svalbard continental margin, using the ODP holes 910C and 912A of the Yermak Plateau and the ODP hole 986 west of Svalbard.
Investigate fluid-flow features related to gas hydrate bearing sediments

The cruise may be known as: CAGE17_5

Annual Report 2017

Karin Andreassen — Fri, 03 Feb 2023 00:00:00 +0100

CAGE has completed its first five-year phase as a Centre of Excellence. During this short time, the centre has established itself as a world leader in gas hydrate-related environmental and climate research. This achievement was recognised by our highly successful midway-evaluation in 2017, where significant funding was secured from the Norwegian Research Council for another five years.