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New xenophyophores (Foraminifera, Monothalamea) from the eastern Clarion-Clipperton Zone (equatorial Pacific)
(Journal article; Tidsskriftartikkel, 2024-03-06)Xenophyophores are large, agglutinated foraminifera that dominate the benthic megafauna in some parts of the deep sea. Here, we describe an assemblage of largely fragmentary specimens from the Clarion-Clipperton Zone (CCZ), an area of the eastern abyssal Pacific hosting large, commercially significant deposits of polymetallic nodules. We recognised 18 morphospecies of which eight yielded DNA sequences. ... -
Cultural activity and impact of extreme weather events revealed by ambient seismic noise and perspective on quick clay failure monitoring in Oslo, Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-02-01)The study of urban seismic noise offers various approaches to monitor cities, from source identification to structural investigations. We demonstrate its potential to monitor cultural activity and quick clay failure in Oslo, Norway using low-cost seismic sensors. We identify train passages, a rock concert, construction blasts, local earthquakes and a meteor. To retrieve seismic velocity variations ... -
Importance of grain boundary processes for plasticity in the quartz-dominated crust: Implications for flow laws
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-01)When H<sub>2</sub>O is present along grain boundaries, the deformation processes responsible for plasticity in silicate mineral aggregates can deviate from what may be conventionally expected. Although a necessary component of understanding crustal deformation processes, there is no theoretical framework that incorporates grain boundary processes into polycrystalline quartz rheology. To address this ... -
Shifts in Greenland interannual climate variability lead Dansgaard–Oeschger abrupt warming by hundreds of years
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-02-24)During the Last Glacial Period (LGP), Greenland experienced approximately 30 abrupt warming phases, known as Dansgaard–Oeschger (D–O) events, followed by cooling back to baseline glacial conditions. Studies of mean climate change across warming transitions reveal indistinguishable phase offsets between shifts in temperature, dust, sea salt, accumulation, and moisture source, thus preventing a ... -
Lower Cretaceous holostratigraphy in Svalbard: the Arctic key piece of the Boreal basin puzzle
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-25)Lower Cretaceous stratigraphy of the high palaeo-latitude Arctic-Boreal Realm is generally more poorly understood than its lower-latitude Tethyan counterpart, prohibiting regional correlations and evaluation of global climate dynamics during this important high-pCO2 period. In this paper, a holostratigraphic scheme and lithostratigraphic revision are presented for the Valanginian–lower Barremian, ... -
Hydroclimate intensification likely aided glacier survival on Svalbard in the Early Holocene
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-02-11)Accelerated Arctic warming and wetting has global impacts, as the region’s glaciers and ice caps respond to variations in temperature and precipitation, impacting global sea-level change. But as the observations needed to calibrate models are scarce, predictions cannot confirm if increases in snowfall can help offset melt. Here, we analyze two 14,000-year-long glacier-fed lake sediment records ... -
Lithospheric mantle heterogeneity beneath the Siberian craton: Evidence from garnet xenocryst database with implications for kimberlite compositions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-22)This contribution reports some 16,000 major and minor element analyses of garnet xenocrysts derived from 18 (out of the 21 known) kimberlite fields of the Yakutian Kimberlite Province (YaKP) on the Siberian craton in Russia. Using TiO<sub>2</sub>–in–garnet as an indicator of heterogeneity within the subcontinental lithospheric mantle (SCLM), as well as garnet mg# (mg#=Mg<sup>2+</sup>/(Mg<sup>2+</s ... -
Carbon cycling during the India-Asia collision revealed by δ26Mg–δ66Zn–δ98Mo evidence from ultrapotassic volcanoes in NW Tibet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-18)India-Asia continental collision–induced volcanic gas emissions are thought to have played an important role in driving Cenozoic atmospheric CO<sub>2</sub> variations, yet the details of how the deep carbon cycle may influence volcanic CO<sub>2</sub> degassing are not understood. We present a novel study employing Mg-Zn-Mo isotopic compositions of Cenozoic ultrapotassic lavas from NW Tibet. The ... -
Proglacial methane emissions driven by meltwater and groundwater flushing in a high-Arctic glacial catchment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-02-06)Glacial groundwater is a conduit for geologic methane release in areas of glacier retreat on Svalbard, representing a large, climate-sensitive source of the greenhouse gas. Methane emissions from glacial melt rivers are known to occur in other regions of the Arctic, but such emissions have not yet been considered on Svalbard. Over the summer of 2021, we monitored methane concentrations in the ... -
Crustal Heterogeneity Onshore Central Spitsbergen: Insights From New Gravity and Vintage Geophysical Data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-01-23)Gravity data provide constraints on lateral subsurface density variations and thus provide crucial insights into the geological evolution of the region. Previously, gravity data from the Norwegian Arctic archipelago of Svalbard comprised an onshore regional gravity database with coarse station spacing of 2–20 km, offshore gravity profiles acquired in some fjords, airborne gravity, and satellite ... -
Links between Calcite Kimberlite, Aillikite and Carbonatite in West Greenland: Numeric Modeling of Compositional Relationships
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-05)Textural, mineralogical and mineral compositional observations in a suite of Neoproterozoic aillikite and calcite kimberlite dykes from southern West Greenland point to consistent variations in melt major element compositions amongst these silica-undersaturated magma types. The aillikites have notably higher bulk SiO<sub>2</sub>/CO<sub>2</sub>, H<sub>2</sub>O/CO<sub>2</sub> and K<sub>2</sub>O compared ... -
The newly discovered Attu carbonatite of West Greenland: A Mesoproterozoic dyke intrusion enriched in primary Sr-Ba-REE minerals
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-22)A newly discovered ca. 1.5 Ga old carbonatite dyke in central West Greenland is characterized by very high contents of rare earth elements (REE), Sr and Ba (up to 12.4 wt% total REE, 14.6 wt% SrO and 12.4 wt% BaO). The dyke occurrence is named ‘Attu carbonatite’ after the nearby village Attu. The carbonatite is primarily composed of carbonate minerals such as Sr-rich calcite (CaCO<sub>3</sub>) and ... -
Sea ice variability from the penultimate glacial to the last interglacial in the Eastern Fram Strait
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-01-28)The ongoing reduction of Arctic sea ice underscores the need to understand the drivers behind sea ice variability and associated ocean-climate impacts. The Last Interglacial, Marine Isotope (sub)Stage (MIS) 5e, and its transitions offer insights into sea ice variability during a period warmer than pre-industrial, and intervals of large climatic changes. This study examines a marine sediment core ... -
The Elusive Congo Craton Margin During Gondwana Breakup: Insights from Lithospheric Mantle Structure and Heat Flow beneath the Xaudum Kimberlite Province, NW Botswana
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-16)The continental lithospheric mantle (CLM) beneath the southern margin of the Congo craton has remained elusive, mainly because of the thick Phanerozoic sedimentary cover concealing possible kimberlite and lamproite diatremes. In this study, we explore this lithospheric mantle section using major and trace element compositions of mantle-derived clinopyroxene and garnet xenocrysts from kimberlites of ... -
The International Bathymetric Chart of the Arctic Ocean Version 5.0
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-12-21)Knowledge about seafloor depth, or bathymetry, is crucial for various marine activities, including scientific research, offshore industry, safety of navigation, and ocean exploration. Mapping the central Arctic Ocean is challenging due to the presence of perennial sea ice, which limits data collection to icebreakers, submarines, and drifting ice stations. The International Bathymetric Chart of the ... -
Norwegian Sea Oceanic Basin and Prograded Margins Composite Tectono-Sedimentary Element
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-01)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 ... -
Devonian–Mississippian magmatism related to extensional collapse in Svalbard: implications for radiating dyke swarms
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-12-12)Background - Despite extensive studies of the Mesozoic–Cenozoic magmatic history of Svalbard, little has been done on the Paleozoic magmatism due to fewer available outcrops.<p> <p>Methods - 2D seismic reflection data were used to study magmatic intrusions in the subsurface of eastern Svalbard. Results This work presents seismic evidence for west-dipping, Middle Devonian–Mississippian sills in ... -
An Arctic analogue for the future exploration of possible biosignatures on Enceladus
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-01-23)Methane-rich emissions to the seafloor along the Arctic mid-oceanic ridge hold strong astrobiological significance, as they may represent analogues of putative hydrothermal vent environments on Enceladus. Although such environments on Enceladus would be ideal to sample in future astrobiological missions, this may not be possible due to technological and logistical limitations. As such, searching for ... -
Giant pit craters on the modern seafloor above magma-induced hydrothermal vent complexes of Scotia Sea, offshore Antarctica
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-01-24)Massive injection of <sup>13</sup>C depleted carbon to the ocean and atmosphere coincided with major environmental upheaval multiple times in the geological record. For several events, the source of carbon has been attributed to explosive venting of gas produced when magmatic sills intruded organic-rich sediment. The concept mostly derives from studies of a few ancient sedimentary basins with numerous ... -
Sanctuary for vulnerable Arctic species at the Borealis Mud Volcano
(Journal article; Tidsskriftartikkel; Peer reviewed, 2025-01-27)Borealis is a recently discovered submerged mud volcano in the Polar North Atlantic, differing from the numerous methane seepages previously identified in the region. Here we show in situ observations from a remotely operated vehicle (ROV), capturing the release of warm (11.5 °C) Neogene sediments and methane-rich fluids from a gryphon at Borealis. The surrounding seafloor within the mud volcano ...
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