Institutt for geovitenskap: Nye registreringer
Viser treff 821-840 av 1025
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Depositional environment, ichnological features and oxygenation of Permian to earliest Triassic marine sediments in central Spitsbergen, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)Late Early Permian–lowermost Triassic carbonate, siliceous (spiculites) and clastic marine sediments in the Marmierfjellet area (Isfjorden, central Spitsbergen) contain a relatively diverse and abundant trace fossil assemblage providing important information about the depositional processes. The Vøringen Member (Late Artinskian–Kungurian) of the Kapp Starostin Formation (Late Artinskian–? Changhsingian) ... -
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 ... -
Two-stage exhumation of subducted Saxothuringian continental crust records underplating in the subduction channel and collisional forced folding (Krkonoše-Jizera Mts., Bohemian Massif)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08)The Krkonoše-Jizera Massif in the northern part of the Variscan Bohemian Massif provides insight into the exhumation mechanisms for subducted continental crust. The studied region exposes a relatively large portion of a flat-lying subduction-related complex that extends approximately 50 km away from the paleosuture. wide extent of HP-LT metamorphism has been confirmed by new P-T estimates indicating ... -
Ice-sheet-driven methane storage and release in the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-07)It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of B1,900 fluid escape features—pockmarks and active gas flares—across a previously glaciated ... -
Evidence for ice-free summers in the late Miocene central Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-04)Although the permanently to seasonally ice-covered Arctic Ocean is a unique and sensitive component in the Earth’s climate system, the knowledge of its long-term climate history remains very limited due to the restricted number of pre-Quaternary sedimentary records. During Polarstern Expedition PS87/2014, we discovered multiple submarine landslides along Lomonosov Ridge. Removal of younger ... -
Deconvoluting complex structural histories archived in brittle fault zones
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-16)Brittle deformation can saturate the Earth’s crust with faults and fractures in an apparently chaotic fashion. The details of brittle deformational histories and implications on, for example, seismotectonics and landscape, can thus be difficult to untangle. Fortunately, brittle faults archive subtle details of the stress and physical/chemical conditions at the time of initial strain localization ... -
Constraints on oceanic methane emissions west of Svalbard from atmospheric in situ measurements and Lagrangian transport modeling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-10) -
Long-lasting Cadomian magmatic activity along an active northern Gondwana margin: U–Pb zircon and Sr–Nd isotopic evidence from the Brunovistulian Domain, eastern Bohemian Massif
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-03)Cadomian magmatic complexes of the Brunovistulian Domain crop out at the eastern termination of the Bohemian Massif. However, the age, nature and geotectonic affinity of some of pre-Variscan (meta-)igneous rock complexes from this domain are still unknown. Geochronological and geochemical study of the granitic rocks across the Brunovistulian Domain reveals new information about the timing and nature ... -
Benthic foraminiferal growth seasons implied from Mg/Ca-temperature correlations for three Arctic species
(Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-11-22)Core-top sediment samples from Kongsfjorden, Svalbard, and adjacent fjord and shelf areas were collected in order to investigate a potential relationship between Mg/Ca-ratios of Arctic benthic foraminifera and the ambient bottom water temperatures (BWT). The area is influenced by large seasonal variation in factors such as light and temperature, which is further strengthened by oceanographic shifts, ... -
Paleoceanographic development during the last deglaciation and Holocene, over the Bear Island slide scar, SW Barents Sea
(Master thesis; Mastergradsoppgave, 2017-02-02)The investigated sediment core HH13-243 GC is located under the present flow of the warm and saline Atlantic Water (AW), but close to, glaciated continental margins. The core site is situated in an area that is sensitive to changes and reflects the paleoceanography of the northernmost Norwegian Sea and the Western Barents Sea. We investigated the changes in inflow of Atlantic water and the ... -
Divergent drift of Adriatic-Dinaridic and Moesian carbonate platforms during the rifting phase witnessed by Triassic MVT Pb-Zn and SEDEX deposits; a metallogenic approach
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)Early-intracontinental rifting of Pangea was a result of thermal doming in Uppermost Permian time giving rise to the formation of horst-graben structures, followed by slow subsidence, marine transgression and evaporite deposition. The consequences of incipient magmatism and a high heat flow are numerous geothermal fields and subterrestrial hydrothermal siderite-barite-polysulfide deposits (PALINKAŠ ... -
The Ljubija geothermal field: A herald of the Pangea break-up (NW Bosnia and Herzegovina)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)The Ljubija ore deposits are the loci typici of siderite-barite-polysulphide deposits within the Inner Dinarides, Gemerides and Eastern Alps. Numerous sites of ore outcrops, smaller or larger ore bodies of mineralization, consisting of Fe carbonates, sulphides, barite and fluorite are scattered over an area of 150 square km. The half billion tons of iron ore resources occur as replacement in ... -
Porphyry Cu mineralization related to the small Tertiary volcanic intrusions in the Bučim ore deposit, Eastern Macedonia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)The paper presents data about the geology, geochemistry, structure, genesis and specific features of the Bučim porphyry Cu deposit which is actively mined in Macedonia. The porphyry mineralization (0.3 % Cu, 0.3-0.5 ppm Au) is spatially and temporarily associated with Tertiary subvolcanic intrusions of latitic and latitic-andesitic composition. The intrusions occurred during Oligo-Miocene time ... -
Origin and K-Ar age of the phreatomagmatic breccia at the Trepča Pb-Zn-Ag skarn deposit, Kosovo: Implications for ore-forming processes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)The Trepča Pb-Zn-Ag skarn deposit in Kosovo is spatially and temporarily related to the phreatomagmatic breccia of Oligocene age (~23Ma). The deposit shows features typical for skarn deposits worldwide, including a stage of isochemical metamorphism, a prograde stage of an anhydrous, low oxygen and low sulfur fugacity character, and a retrograde stage characterized by an increase in the water ... -
The last 2 Myr of accretionary wedge construction in the central Hikurangi margin (North Island, New Zealand): Insights from structural modeling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-17)Three depth-converted and geologically interpreted seismic profiles provide a clear image of the offshore outer accretionary wedge associated with oblique subduction of the Pacific Plate beneath the central Hikurangi margin. Plio-Quaternary turbidites deposited over the pelagic cover sequence of the Hikurangi Plateau have been accreted to the margin by imbrication along E-verging thrust faults that ... -
Splay fault branching from the Hikurangi subduction shear zone: Implications for slow slip and fluid flow
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-25)Prestack depth migration data across the Hikurangi margin, East Coast of the North Island, New Zealand, are used to derive subducting slab geometry, upper crustal structure, and seismic velocities resolved to ∼14 km depth. We investigate the potential relationship between the crustal architecture, fluid migration, and short-term geodetically determined slow slip events. The subduction interface is ... -
Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08-20)The shallow subsurface hydrography in the southern Norwegian Sea during the past 135,000 years was investigated using parallel measurements of Mg/Ca and δ18O in shells of the planktic foraminiferal species Neogloboquadrina pachyderma. Two cleaning methods were applied prior to Mg/Ca analysis, “Mg cleaning” and “full cleaning” methods. Different results were obtained, which are most likely due to a ... -
Simulating seismic chimney structures as potential vertical migration pathways for CO2 in the Snøhvit area, SW Barents Sea: model challenges and outcomes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-16)Carbon capture and storage (CCS) activities at the Snøhvit field, Barents Sea, will involve carrying out an analysis to determine which parameters affect the migration process of CO2 from the gas reservoir, to what degree they do so and how sensitive these parameters are to any changes. This analysis will aim to evaluate the effects of applying a broad but realistic range of reservoir, fault and gas ... -
The build-up, configuration, and dynamical sensitivity of the Eurasian ice-sheet complex to Late Weichselian climatic and oceanic forcing
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-01)The Eurasian ice-sheet complex (EISC) was the third largest ice mass during the Last Glacial Maximum (LGM), after the Antarctic and North American ice sheets. Despite its global significance, a comprehensive account of its evolution from independent nucleation centres to its maximum extent is conspicuously lacking. Here, a first-order, thermomechanical model, robustly constrained by empirical evidence, ... -
Evolution of a high-latitude sediment drift inside a glacially-carved trough based on high-resolution seismic stratigraphy (Kveithola, NW Barents Sea)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-01)Kveithola is a glacially-carved, E-W trending trough located in the NW Barents Sea, an epicontinental shelf sea of the Arctic Ocean located off northern Norway and Russia. A set of confined sediment drifts (the “Kveithola Drift”) is located in the inner part of the trough. In general, drift deposits are commonly characterized by high lateral continuity, restricted occurrence of hiatuses and relatively ...