PALMAR – Paleogen bassengutvikling på Vøring- og Møremarginene

• Senger, Kim; Betlem, Peter; Helland-Hansen, Annikken; Horota, Rafael Kenji; Kämpf, Horst & Kontny, Agnes M. [Vis alle 11 forfattere av denne artikkelen] (2024). Multi-disciplinary geoscientific expedition to Woodfjorden, NW Svalbard: Field sites, methods, and preliminary results. Czech Polar Reports. ISSN 1805-0689. 13(2), s. 142–161. doi: 10.5817/CPR2023-2-12. Fulltekst i vitenarkiv Vis sammendrag

  The Woodfjorden area of northern Spitsbergen (NW Svalbard) offers access to the world’s northernmost onshore thermal springs, extinct Pleistocene alkali basaltic volcanoes and Miocene flood basalts including extensive hyaloclastites. In July 2023, we undertook a 14-day international multi-disciplinary geoscientific expedition to Woodfjorden-Bockfjorden to investigate the Cenozoic geological evolution of the area. The expedition objectives spanned a wide range of scientific topics from sampling of fluids and gas in the thermal springs to constraining the lithosphere by acquiring magnetotelluric data and sampling volcanic rocks. More specifically, we have 1) conducted gas, fluid and travertine sampling at the thermal springs of Gygrekjelda, Jotunkjeldene and Trollkjeldene, 2) mapped and sampled the Quaternary volcanic centers at Sverrefjellet and Halvdanpiggen, 3) sampled the Miocene basalts of the Seidfjellet Formation along seven profiles plus the underlying Devonian sedimentary rocks, 4) acquired magnetotelluric data at 12 stations along both coasts of Woodfjorden and Bockfjorden and 5) collected extensive digital geological data (digital outcrop models and photospheres) using unmanned aerial vehicles (UAVs; also known as drones). The collected samples are currently being analyzed for, amongst others, petrology, geochemistry and geochronology. In this contribution, we report on the expedition’s background, scientific objectives and present selected preliminary results such as field parameters from the thermal springs (temperature, pH, electrical conductivity), magnetic susceptibility of volcanic rocks and digital outcrop models plus photospheres.

• Faleide, Jan Inge; Abdelmalak, Mohamed Mansour; Zastrozhnov, Dmitrii; Lasabuda, Amando P. E.; Hjelstuen, Berit Oline Blihovde & Laberg, Jan Sverre [Vis alle 7 forfattere av denne artikkelen] (2024). Norwegian Sea Oceanic Basin and Prograded Margins Composite Tectono-Sedimentary Element. Geological Society of London Memoirs. ISSN 0435-4052. 57. doi: 10.1144/M57-2023-26. Vis sammendrag

  The Norwegian Sea oceanic basins and prograded margins have developed since NE Atlantic break-up in the earliest Eocene. Significant amounts of sediments were fed to the regionally subsiding and widening Norwegian Sea during the Cenozoic as a result of several phases of uplift and erosion of the bounding shelves and their hinterland. Despite an overall passive-margin evolution, the area experienced tectonic events and associated processes that interrupted the regional subsidence, causing contraction/inversion and tilting. The post-break-up depositional history of the mid-Norwegian margin comprises two main stages: (1) middle Eocene–Pliocene margin subsidence and relatively modest sedimentation during a period of climatic decline; and (2) latest Pliocene–Pleistocene full-scale northern hemisphere glaciations that resulted in deep erosion of shelves and hinterlands, and very high sedimentation rates and large-scale continental margin progradation. Slope failures within rapidly deposited glacial sediments affected both prograded margins, releasing large slides that travelled downslope into the oceanic Norway and Lofoten basins. Despite a long exploration history for hydrocarbon prospects in deeper waters and large amounts of data acquisition, no significant discovery has been made.

• Berndt, Christian; Planke, Sverre; Alvarez Zarikian, Carlos A.; Frieling, Joost; Jones, Morgan Thomas & Millett, John M. [Vis alle 36 forfattere av denne artikkelen] (2023). Shallow-water hydrothermal venting linked to the Palaeocene–Eocene Thermal Maximum. Nature Geoscience. ISSN 1752-0894. 16, s. 803–809. doi: 10.1038/s41561-023-01246-8. Fulltekst i vitenarkiv Vis sammendrag

  The Palaeocene–Eocene Thermal Maximum (PETM) was a global warming event of 5–6 °C around 56 million years ago caused by input of carbon into the ocean and atmosphere. Hydrothermal venting of greenhouse gases produced in contact aureoles surrounding magmatic intrusions in the North Atlantic Igneous Province have been proposed to play a key role in the PETM carbon-cycle perturbation, but the precise timing, magnitude and climatic impact of such venting remains uncertain. Here we present seismic data and the results of a five-borehole transect sampling the crater of a hydrothermal vent complex in the Northeast Atlantic. Stable carbon isotope stratigraphy and dinoflagellate cyst biostratigraphy reveal a negative carbon isotope excursion coincident with the appearance of the index taxon Apectodinium augustum in the vent crater, firmly tying the infill to the PETM. The shape of the crater and stratified sediments suggests large-scale explosive gas release during the initial phase of vent formation followed by rapid, but largely undisturbed, diatomite-rich infill. Moreover, we show that these vents erupted in very shallow water across the North Atlantic Igneous Province, such that volatile emissions would have entered the atmosphere almost directly without oxidation to CO2 and at the onset of the PETM.

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