Methane distribution in Holocene marine sediments in the Bornholm Basin, southern Scandinavia

The Baltic Sea is an ideal natural laboratory to study the methane cycle in the framework of diagenetic processes. In this paper we present preliminary geological mapping results from project Baltic Gas, a research project with the overall aim to contribute to the development of a scientific basis for long term sustainable use and protection of the Baltic Sea ecosystem. The Baltic Sea is a marginal sea with a strong permanent haline stratification, which leads to oxygen-poor bottom waters, and which is sometimes interrupted by oxygen-rich saltwater flowing in from the North Sea. The history of the Baltic Sea has resulted in deposition of organic-rich Holocene marine sediments that overlie glacial, late-glacial and early Holocene organic-poor sediments.