English
norskBlar i forfatter "Thorsnes, Terje"
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Gas seeps in Norwegian waters – distribution and mechanisms
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-01)Gas seeps and fluid-flow related seabed features are found over the entire Norwegian exclusive economic zone (EEZ). Multibeam water-column data from c. 136 000 km2 has revealed more than 5 000 gas seeps. Most of the gas seeps seem to have biogenic, thermogenic or mixed origin; some may be of abiotic origin. The spatial distribution of the gas seeps appears to correlate with: 1 – structural highs ... -
Long-term fluid expulsion revealed by carbonate crusts and pockmarks connected to subsurface gas anomalies and palaeo-channels in the central North Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-19)Gas seepage through the seafloor into the water column is inferred based on acoustic mapping, video observations and geochemical analyses at multiple locations in the Viking Graben and Utsira High areas of the central North Sea. Flares in the Viking Graben occur both inside and along the periphery of a submarine melt water channel where pockmarks (up to 500 m in diameter) and methane-derived carbonate ... -
New cold seep sites on the continental slope southwest to Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-09)We discovered seafloor features such as bacterial mats and carbonate crusts typical for active methane seeps on the continental slope southwest of Svalbard. These features are associated with two main northwest-southeast trending morphological structures that are oriented parallel to the regional continental slope. Both structures occur at c. 800 m water depth, at the boundary between the Storfjorden ... -
Strategy for Detection and High-Resolution Characterization of Authigenic Carbonate Cold Seep Habitats Using Ships and Autonomous Underwater Vehicles on Glacially Influenced Terrain
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-26)Cold seep habitats with authigenic carbonates and associated chemosynthetic communities in glacially influenced terrains constitute an important part of the benthic ecosystems, but they are difficult to detect in large-scale seabed surveys. The areas they occupy are normally small, and survey platforms and sensors allowing high-resolution spatial characterization are necessary. We have developed a ... -
Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean–atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents ...
