Pockmarks, gas flares, tectonic features and processes leading to their formation, southwestern Barents Sea

Abstract

The project is aimed to achieve a better understanding of shallow geological\/seabed conditions and processes to support technical and environmental aspects of exploration and production along the western margin of the Hammerfest Basin and Loppa High, and in the Tromsø Basin\/Ingøydjupet area.\rThe project has had the following subgoals:\r- Detection of water column gas anomalies at selected pockmark locations\r- Identification of neotectonic features\rThe project has the following results:\r- A total of 16 gas flares were identified using the water column data collected using the multibeam echosounder system during cruises in 2008 and 2009. The gas flares are observed to occur mainly outside the pockmark areas along regional faults where the seabed is incised by iceberg ploughmarks. No correlation is found between flare occurrence and tidal cycles but a full tidal cycle monitoring has not been carried out to substantiate it.\r- Pockmarks are interpreted to be formed after deglaciation due to melting of gas hydrates. They are probably not active at present.\r- Multiple fault\/lineament locations were identified. They are observed to be of reverse faults with thrusted part along the western side and deeper basin with larger sediment thickness along the eastern side. The faults are observed to be covered by undisturbed glaciomarine\/marine sediments deposited after the last deglaciation, indicating little neotectonic activity.