Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Maria S. Merian	MSM21-4	13.08.2012 - 11.09.2012		Norwegian Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Berndt Christian	Helmholtz Centre for Ocean Research Kiel (GEOMAR)	Reykjavik	Emden

Ziel der Reise / Objectives of Cruise:

The main goal of MSm²1/4 was the study of gas hydrate system off Svalbard. We addressed this through a comprehensive scientific programme comprising manned submersible dives, seismic and heat flow measurements, sediment coring, water column biogeochemistry and bathymetric mapping. At the interception of the Knipovich Ridge and the continental margin of Svalbard we collected seismic data and four heat flow measurements, which revealed that the extent of hydrates is significantly larger than previously thought and that the gas hydrate system is influenced by heat from the oceanic spreading centre. At the landward termination of the hydrate stability zone we investigated the mechanisms that lead to degassing by taking sediment cores, sampling of carbonates, and measuring the methane turn-over rates in the water column. It turned out that the observed gas seepage must have been ongoing for a long time and that decadal scale warming is an unlikely explanation for the observed seeps. Instead seasonal variations in water temperatures seem to control episodic hydrate formation and dissociation explaining the location of the observed seeps. The water column above the gas flares is rich in methane and methanotrophic microorganisms thrive in this water mass turning over most of the methane that escapes from the sea floor. We also surveyed large, until then uncharted parts of the margin in the northern part of the gas hydrate province. Here, we discovered a several tens of kilometres wide submarine landslide complex. This slide is unusual in the sense that it is not located at the mouth of a cross shelf trough such as other submarine landslides on the glaciated continental margins around the North Atlantic. Thus, the most widely accepted explanation for the origin of such slides, i.e. overpressure development due to deposition of glacial sediments on top of water rich contourites, is not applicable. Instead we find gas-hydrate-related bottom simulating reflectors underneath the headwalls of this slide complex, possibly indicating that subsurface fluid migration plays a major role in its genesis.

Messungen / Measurements