Western Baltic Sea, Kattegat, and Skagerrak

This area covers a broad range of sites ideal for the study of

typical sub-surface methane barriers,

gas-charged sediments without apparent methane escape, and

migrating bubbles and a near-surface methane front.

In connection with detailed acoustic sea floor mapping in the region by the partner GEUS, extensive information is already available on the distribution of gas in the sediments. Deep and shallow seismic data as well as deep drillings have provided an exellent background information on subsurface geology including faults and shallow gas reservoirs. In , optimisation of acoustic methods for the mapping of gas concentrations and sub-bottom depth of gas bubbles will be performed in northern Kattegat, which offers a wide range of gas occurrencies in different types of sediments. Slope instability may be reponsible for many of the gas-escape phenomena on the southern slope of Skagerrak. These have been partly mapped during earlier studies.

The North Sea

The North Sea is one of the economically most important European margins with respect to the occurrence and exploitation of natural gas. The areas include surface structures such as gas seeps, pock marks and carbonate chimneys derived from diffuse or focused emissions of methane and around which methane transformations will be studied. Many gas seeps have been discovered in the North Sea associated with microbial mats, carbonate reefs and cold water corals by the partner STATOIL.

Black Sea north-western shelf and slope

As the largest anoxic basin on earth, the Black Sea provides an ideal model system for studies of anaerobic methane oxidation. The entire sea floor below 150 m is overlain by an anoxic water column, and sulfate reduction, methanogenesis and methane oxidation are the totally dominant terminal processes of carbon flux in the sediments. Anaerobic methane oxidation takes place in the subsurface and at the sediment surface at gas vents. The occurrence of methane seeps and carbonate structures have been mapped through extensive acoustic surveys by the local partners GeoEcoMar and IBSS.

Other ocean margin sites

Other ocean margin regions will be studied after careful selection depending on their relevance for the project and on cruise and sample availability.

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