Artikler, rapporter og annet (geovitenskap): Nye registreringer
Viser treff 761-780 av 816
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Position, swimming direction and group size of fin whales (Balaenoptera physalus) in the presence of a fast-ferry in the Bay of Biscay
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-12)We analyze group size, swimming direction and the orientation of fin whales relative to a fast ferry in the Bay of Biscay. Fin whale groups (≥3 individuals) were on average closer to the vessel than single individuals and pairs (F1,114 = 4.94, p = 0.028) and were more often observed within a high-risk angle ahead of the ferry (binomial probability: p = 7.60 × 10−11). Also, small groups tend to swim ... -
Gas hydrate stability zone of the Barents Sea and Kara Sea region
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-29)In this study we assess the present-day gas hydrate stability zone for the Barents Sea and Kara Sea region. Thereby, we make use of a data-based 3D lithosphere-scale pressure and thermal model. The resulting gas hydrate stability zone varies within >1km across the study area and strongly correlates with the local geological settings and the corresponding geothermal gradient. Gas hydrates containing ... -
Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-30)It has been argued that the infiltration and retention of meltwater within firn across the percolation zone of the Greenland ice sheet has the potential to buffer up to ∼ 3.6 mm of global sea-level rise (Harper et al., 2012). Despite evidence confirming active refreezing processes above the equilibrium line, their impact on runoff and proglacial discharge has yet to be assessed. Here, we compare ... -
Structure and flow properties of syn-rift border faults: The interplay between fault damage and fault-related chemical alteration (Dombjerg Fault, Wollaston Forland, NE Greenland)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-29)Structurally controlled, syn-rift, clastic depocentres are of economic interest as hydrocarbon reservoirs; understanding the structure of their bounding faults is of great relevance, e.g. in the assessment of fault-controlled hydrocarbon retention potential. Here we investigate the structure of the Dombjerg Fault Zone (Wollaston Forland, NE Greenland), a syn-rift border fault that juxtaposes syn-rift ... -
Sedimentary ancient DNA from Lake Skartjørna, Svalbard: Assessing the resilience of arctic flora to Holocene climate change
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-11) -
Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-26)In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species ... -
Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-07)We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high ... -
North Atlantic warming during Dansgaard-Oeschger events synchronous with Antarctic warming and out-of-phase with Greenland climate
(Journal article; Peer reviewed; Tidsskriftartikkel, 2016-02-05)The precise reason for the differences and out-of-phase relationship between the abrupt Dansgaard- Oeschger warmings in the Nordic seas and Greenland ice cores and the gradual warmings in the southcentral Atlantic and Antarctic ice cores is poorly understood. Termed the bipolar seesaw, the differences are apparently linked to perturbations in the ocean circulation pattern. Here we show that ... -
Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-21)High-resolution swath-bathymetry data from inner Kongsfjorden, Svalbard, reveal characteristic landform assemblages formed during and after surges of tidewater glaciers, and provide new insights into the dynamics of surging glaciers. Glacier front oscillations and overriding related to surge activity lead to the formation of overridden moraines, glacial lineations of two types, terminal moraines, ... -
Middle to late Holocene paleoproductivity reconstructions for the western Barents Sea: a model-data comparison
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-30)In this study we focus on late Holocene primary productivity (PP) variability in the western Barents Sea and its response to variable sea ice coverage by combining PP reconstructed from several sediment cores with regional PP trends simulated with a well-constrained organic facies model, OF-Mod 3D. We find that modern production rates reconstructed from buried marine organic matter ... -
Natural variability of benthic foraminiferal assemblages and metal concentrations during the last 150 years in the Ingøydjupet trough, SW Barents Sea.
(Journal article; Tidsskriftartikkel, 2015-12)While today the SW Barents Sea is a relatively un-impacted and uncontaminated area, industrial activities related to the petroleum industry are projected to increase in the coming decades. This makes the area a valuable natural laboratory to establish pre-impacted baselines as a precursor for future seabed monitoring programs. Here we present benthic foraminiferal assemblages and metal concentrations ... -
Variability of present and past PAH concentrations in sediments of the SW Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-09)The concentration and distribution of polyaromatic hydrocarbons (PAHs) in surface and subsurface sediment samples from Tromsøflaket and Ingøydjupet, southwestern Barents Sea, were investigated in order to provide insight into the levels and origins of PAHs in a region with petroleum activities. PAH profiles in sediments were evaluated in context with sediment grain size and total organic carbon ... -
Biocryomorphology: integrating microbial processes with ice surface hydrology, topography and roughness
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-02) -
UAV photogrammetry and structure from motion to assess calving dynamics at Store Glacier, a large outlet draining the Greenland ice sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-06)This study presents the application of a costeffective, unmanned aerial vehicle (UAV) to investigate calving dynamics at a major marine-terminating outlet glacier draining the western sector of the Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired over 2000 overlapping, geotagged images of the calving front at an ∼ 40 cm ground sampling ... -
Seabed morphology and sedimentary processes on high-gradient trough mouth fans offshore Troms, northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-01)Trough mouth fans (TMF) situated at the mouths of formerly glaciated cross-shelf troughs are important paleoclimatic archives. Whereas the sedimentary processes of large, low-gradient TMFs have received considerable interest, little attention has been paid to the other end member of this landform class, i.e. TMFs with higher slope gradients. Detailed swath-bathymetric data and seismic profiles from ... -
Microbial methane formation in deep aquifers of a coal-bearing sedimentary basin, Germany
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-20)Coal-bearing sediments are major reservoirs of organic matter potentially available for methanogenic subsurface microbial communities. In this study the specific microbial community inside lignite-bearing sedimentary basin in Germany and its contribution to methanogenic hydrocarbon degradation processes was investigated. The stable isotope signature of methane measured in groundwater and coal-rich ... -
The Miocene-Pliocene boundary and the Messinian Salinity Crisis in the easternmost Mediterranean: Insights from the Hatay Graben (Southern Turkey)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-02)The Hatay Graben is one of three easternmost basins in the Mediterranean that preserve sediments that span the Miocene–Pliocene boundary, including gypsums from the Messinian Salinity Crisis (MSC). Here we integrate existing data and present new sedimentological and micropalaeontological data to investigate the palaeoenvironments of late Miocene to early Pliocene deposits and place this important ... -
Geological modelling for investigating CO2 emissions in Florina Basin, Greece
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-15)This paper presents an investigation of naturally occurring CO2 emissions from the Florina natural analogue site in Greece. The main objective was to interpret previously collected depth sounding data, convert them into surfaces, and use them as input to develop, for the rst time, 3D geological models of the Florina basin. By also locating the extent of the aquifer, the location of the CO2 ... -
Changing surface–atmosphere energy exchange and refreezing capacity of the lower accumulation area, West Greenland
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-18)We present 5 years (2009–2013) of automatic weather station measurements from the lower accumulation area (1840 m a.s.l. – above sea level) of the Greenland ice sheet in the Kangerlussuaq region. Here, the summers of 2010 and 2012 were both exceptionally warm, but only 2012 resulted in a strongly negative surface mass budget (SMB) and surface meltwater run-off. The observed run-off was ... -
Bivalve shell horizons in seafloor pockmarks of the last glacial-interglacial transition suggest a thousand years of methane emissions in the Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-05)We studied discrete bivalve shell horizons in two gravity cores from seafloor pockmarks on the Vestnesa Ridge (1200 m water depth) and western Svalbard (798000 N, 068550 W) to provide insight into the temporal and spatial dynamics of seabed methane seeps. The shell beds, dominated by two genera of the family Vesicomyidae: Phreagena s.l. and Isorropodon sp., were 20–30 cm thick and centered at ...