Siste publikasjoner

• Aarseth, Iselin; Minakov, Alexander; Shulgin, Alexey; Hauge, Brede Engum; Breivik, Asbjørn & Faleide, Jan Inge [Vis alle 8 forfattere av denne artikkelen] (2025). The Storfjorden earthquake sequence: role of inherited crustal heterogeneity. Geophysical Journal International. ISSN 0956-540X. 243(3). doi: 10.1093/gji/ggaf386. Fulltekst i vitenarkiv Vis sammendrag

  A strong earthquake sequence in Storfjorden, south of Svalbard, was initiated by an Mw 6.1 event on 2008 February 21. Earthquake distribution and fault plane solutions indicate that seismic activity is controlled by unmapped NE-SW striking oblique-normal faults, contrasting with the major N-S oriented faults mapped onshore Svalbard. We present a geophysical model derived from an ocean bottom seismometer profile crossing the seismogenic zone to identify structures in the crust and uppermost mantle that potentially control the earthquake source mechanism. Traveltime forward modelling using ray tracing, combined with traveltime tomography and gravity-magnetic modelling, reveal distinct crustal domains across the earthquake region. Crystalline crustal P-wave velocities range from 6.1 to 6.7 km s−1 at the Moho depth in the eastern section. The western profile section exhibits a higher Vp velocity lower crust (6.6–7.0 km s−1) with Vp/Vs ratios of 1.75–1.8 and high density (∼3100 kg m−3). Basement depth reaches 8 km in the west, forming a sedimentary basin, and shallows eastward. The Moho remains relatively flat at 29–32 km depth throughout the profile. The N–S oriented Caledonian suture, identified from deep seismic and potential field data, traverses the Storfjorden earthquake zone. The lithological contacts within the suture zone, inferred from the new OBS data, may facilitate seismic failure oblique to the N–S oriented structure, following the regional stress field.

• Cordoba, Antonio Manjon Cabeza; Rolf, Tobias & Arnould, Maelis Rose Marie (2025). Grain size evolution in mantle convection models promotes continuous rather than episodic tectonics. Physics of the Earth and Planetary Interiors. ISSN 0031-9201. 370. doi: 10.1016/j.pepi.2025.107488. Fulltekst i vitenarkiv Vis sammendrag

  A long-persistent caveat of geodynamic models with Earth-like tectonic behavior is the need of an ad hoc yield stress lower than any laboratory-inferred rock strength. The actual physical processes that govern the strength of the lithosphere are still debated. Grain size reduction due to dynamic recrystallization promotes local weak zones in the lithosphere thereby facilitating lithospheric breakdown and continuous mobile-lid tectonics. Grain growth should instead (re-)strengthen the lithosphere and inhibit this regime. By modeling mantle convection in a spherical annulus, we analyze the impact of grain size evolution (GSE) on the global tectonic style. GSE, together with composite rheology, modifies the diagnostics within one tectonic regime. Indeed, considering grain growth enables high viscosity in the lower mantle, with broad stable plumes. Grain reduction, on the other hand, increases the number of subduction zones, also making them shorter-lived. We find that grain size reduction suppresses episodic behavior and facilitates surface mobility over a range of lithospheric yield stresses, but GSE has no discernible effect on the transition to stagnant-lid tectonics. Moreover, increased grain growth does not result in higher episodicity either. These findings support the relevance of grain size evolution for stabilizing mobile-lid tectonics vs episodic tectonics, and may explain lower mantle features and reconcile geophysical observations; but they also cast doubt on the potential of damage to explain mobile-lid tectonics up to laboratory-inferred strengths.

• Rauer, Heike; Aerts, Conny; Cabrera, Juan; Deleuil, Magali; et, al., including: & Erikson, Anders [Vis alle 847 forfattere av denne artikkelen] (2025). The PLATO mission. Experimental astronomy (Print). ISSN 0922-6435. 59. doi: 10.1007/s10686-025-09985-9. Fulltekst i vitenarkiv Vis sammendrag

  PLATO (PLAnetary Transits and Oscillations of stars) is ESA’s M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2R) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5%, 10%, 10% for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO‘s target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile towards the end of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases.

• Wang, Helene; Magni, Valentina; Conrad, Clinton Phillips & Domeier, Mathew Michael (2025). Hydrous Regions of the Mantle Transition Zone Lie Beneath Areas of Continental Intraplate Volcanism. Geochemistry Geophysics Geosystems. 26(3). doi: 10.1029/2024GC011901. Fulltekst i vitenarkiv Vis sammendrag

  Great volumes of water are carried downward into the mantle transition zone (MTZ, 410–670 km depth) by subducting slabs. If this water is later drawn upward, the resulting mantle melting may generate continental intraplate volcanism (IPV). Despite water's importance, its amount and spatial distribution within the MTZ, and its impact on IPV, are poorly constrained. Here we use plate tectonic reconstructions to estimate the rates and positions of water injection into the MTZ by subducted slabs during the past 400 Myr. This allows us to construct global maps of heterogeneous MTZ hydration, which we then compare to IPV eruption locations from the past 200 Myr. We detect a statistically significant correlation between wet MTZ regions and IPV locations at the surface, but only if slabs sink faster than 1 cm/yr, water remains stored in the MTZ for periods of 30–100 Myr, and IPV eruptions occur 10–30 Myr later. We find that 42%–68% of continental IPV is underlain by wet MTZ, with greater fractions associated with longer MTZ residence time. Hydrous underpinning of continental IPV was highest during the Jurassic, when more extensive slab interaction with the MTZ hydrated a wider area of the MTZ. Since the Cretaceous, continents have been moving over the wet MTZ, increasing IPV possibilities. MTZ regions near the northern Pacific, southern Africa, and western Europe have remained dry by avoiding wet slabs. We suggest that subducted water shapes global patterns of intraplate volcanism, with hydrous upwellings rising from the MTZ to generate continental IPV above wet MTZ regions.

• Tari, Gábor; Bada, Gábor; Kiraly, Agnes; Koroknai, Balázs; Kovács, Gábor & Lemberkovics, Viktor [Vis alle 7 forfattere av denne artikkelen] (2024). The Pannonian Basin: regional geology of a back-arc basin. I Chiarella, Domenico; Scarselli, Nicola & Adam, Jürgen (Red.), Regional Geology and Tectonics Volume 2: Phanerozoic Rift Systems and Sedimentary Basins. Elsevier. ISSN 9780444641366. s. 1–25. doi: 10.1016/B978-0-444-64136-6.00005-1. Fulltekst i vitenarkiv Vis sammendrag

  The Neogene Pannonian Basin has been described as the type example of a Mediterranean back-arc basin where extension did not advance to the opening of an oceanic basin. Due to the removal from the Alpine collision zone, the over thickened lithosphere of the Pannonian region collapsed during the Middle Miocene. The inherited Alpine contractional structural fabric frequently influenced the various styles of syn-rift extension by negative structural inversion. In some of the subbasins of this large basin complex, the geodynamic style of Neogene extensional deformation almost reached the stage of hyperextension but it stopped short of exhuming lower crustal or mantle units at the basin floor. Continental extension terminated due to the space constraints provided by the docking of the surrounding Carpathian thrust-fold belt onto various divergent and transform margin segments of the European plate. The Late Miocene to Pliocene postrift thermal subsidence saw the sedimentation of an unusually thick basin fill local

• Bédard, Jean H.; Dewing, Keith; Grasby, Stephen E.; Nabelek, Peter; Heimdal, Thea Hatlen & Yakymchuk, Chris [Vis alle 10 forfattere av denne artikkelen] (2024). Basaltic sills emplaced in organic-rich sedimentary rocks: Consequences for organic matter maturation and Cretaceous paleo-climate. Geological Society of America Bulletin. ISSN 0016-7606. 136(5-6), s. 1982–2006. doi: 10.1130/B36982.1. Fulltekst i vitenarkiv
• Abdelmalak, Mohamed Mansour; Minakov, Alexander; Faleide, Jan Inge & Drachev, Sergey (2024). Lomonosov Ridge Composite Tectono-Sedimentary Element, Arctic Ocean. Geological Society of London Memoirs. ISSN 0435-4052. 57(1). doi: 10.1144/M57-2022-72. Fulltekst i vitenarkiv Vis sammendrag

  The Lomonosov Ridge (LR) is a sliver of continental crust, a microcontinent that stretches across the Arctic Ocean and separates the Mesozoic Amerasia Basin from the Cenozoic Eurasia Basin. The LR is thought to have been separated from the northern Barents Sea–Kara Sea passive continental margin by continental rifting at about 56–53 Ma and the subsequent formation of the oceanic crust in the Eurasia Basin. Following the nomenclature of this volume, the sedimentary succession of the LR and nearby area forms a composite tectono-sedimentary element containing an assemblage of the following main tectono-sedimentary elements (TSEs): (1) an undefined group of pre-rift TSEs mostly composed of Mesozoic and poorly known Paleozoic successions; (2) the Cretaceous–Paleocene synrift TSE; and (3) the Eocene–Holocene post-rift TSE. The age of the LR's folded and metamorphosed basement can be inferred based on correlations to basement units of the northern Eurasian passive continental margin, which may include a variety of geological structures formed during Timanian, Caledonian, late Paleozoic and Mesozoic orogenic events. The pre-rift TSE includes the oldest and most poorly known offshore sedimentary succession in the Arctic region. The lithostratigraphic units of these basins were mainly characterized from a handful samples collected at the seafloor and by correlation with better known stratigraphy of the conjugate continental margin. The synrift TSE of Cretaceous–Paleocene age has been defined based on seismic data and samples of sedimentary rocks recovered during the Arctic Coring Expedition (ACEX), as well as from seismic facies correlation between the LR and the Podvodnikov–Makarov, Laptev and East Siberian Sea basins. The post-rift Cenozoic sedimentary record was documented by the ACEX well in the central part of the LR.

• Jones, Lewis A. & Domeier, Mathew Michael (2024). A Phanerozoic gridded dataset for palaeogeographic reconstructions. Scientific Data. 11. doi: 10.1038/s41597-024-03468-w. Fulltekst i vitenarkiv Vis sammendrag

  Global Plate Models are widely used in the Earth Sciences to reconstruct the past geographic position of geological and palaeontological samples. However, the application of Global Plate Models to retrieve ‘palaeocoordinates’ is not trivial. Different Global Plate Models exist which vary in their complexity, spatiotemporal coverage, reference frame, and intended use. Consequently, careful consideration of which models are appropriate for any given research question is required. Here, we document and provide access to reconstruction datasets for five Global Plate Models in the palaeomagnetic reference frame. These datasets provide ‘true’ palaeolatitudes for three discrete global grids reconstructed at one-million-year intervals throughout the Phanerozoic (540–0 Ma), offering three key benefits for the Earth Science community: (1) allow users to look up palaeocoordinates for their samples (e.g. fossil occurrences) through simple indexing without having to learn additional software packages; (2) provide palaeocoordinates which have been generated consistently with thorough documentation; (3) provide static files which preserve model output and which can be used to evaluate palaeogeographic differences between Global Plate Models.

• Keyser, William Mark; Müller, Axel; Augland, Lars Eivind & Steiner, Ralf (2024). Rare-metal halos of lithium pegmatite at the Wolfsberg deposit, Austria, and their implications for exploration. Ore Geology Reviews. ISSN 0169-1368. 171. doi: 10.1016/j.oregeorev.2024.106179. Fulltekst i vitenarkiv Vis sammendrag

  The Austroalpine Unit Pegmatite Province (AUPP) in the eastern European Alps hosts abundant Permian-aged, variably rare-metal-enriched pegmatite bodies. However, only a small number containing spodumene [LiAlSi2O6] have been discovered. Here, we characterize three drill cores from the AUPP’s largest spodumene pegmatite resource, the Wolfsberg deposit (Austria), to determine the extent of rare-metal halo formation within different host rock types generated by pegmatite-derived fluids and their applicability to spodumene pegmatite exploration. The halos in both mica schist and amphibolite host rocks, as quantified via whole-rock mass-balance calculations, are characterized by enrichments in Li, Cs, Sn, Rb and Tl, amongst others, elements which were highly mobile during initial interactions between pegmatite-derived fluids and host rocks. The concentrations of these elements within the halos can be several times that present in unaltered host rock. They are most enriched in altered host rock interbedded or at the contacts with pegmatite, and decrease with distance from pegmatite to a distance of at least 4 m in mica schist and <3 m in amphibolite. Lithium, and in mica schist, Cs, have the most consistent and furthest extending halos, with respective concentrations of >590 ppm and >40 ppm in mica schist, and >390 ppm Li in amphibolite indicating proximity to spodumene pegmatite. An ID-TIMS U-Pb titanite age of ca. 103 Ma derived from a rare-metal-enriched amphibolite within the alteration halo reflects recrystallization of the Permian protolith during the Cretaceous Alpine orogeny and indicates preservation of the original pegmatite signature through eclogite-facies metamorphism. Recognition of rare-metal halos surrounding pegmatite at Wolfsberg serves as a potential geochemical exploration tool for spodumene pegmatite within the AUPP and may be applicable to other regions.

• Bjerga, Anders; Stubseid, Håvard Hallås; Pedersen, Leif-Erik Rydland; Corfu, Fernando; Whitehouse, Martin & Pedersen, Rolf B. (2024). Constraints on the Timing and Lower Crustal Accretion at the Schulz Massif, Mohns Ridge, Arctic Mid Ocean Ridges. Geochemistry Geophysics Geosystems. 25(4). doi: 10.1029/2023GC010953. Fulltekst i vitenarkiv Vis sammendrag

  The ultraslow-spreading Mohns Ridge is a key supersegment of the Arctic Mid-Ocean system, where it represents a boundary between the Jan Mayen hotspot in the south and the highly anomalous Knipovich Ridge to the north. Understanding the timing and mode of Plio-Pleistocene seafloor spreading along this ridge segment is critical for establishing the recent geodynamic evolution of the Norwegian-Greenland Sea. To investigate magmatic accretion at this ultraslow spreading ridge, we collected samples from the Schulz Massif, which is located off-axis at 73.4°N and exposes gabbroic intrusives and mantle peridotite. The petrology and petrography of these samples indicate that the exposed crustal section underwent multiple episodes of magmatism, which are characterized by distinct crystal sizes and geochemistry. To calibrate the age of the seafloor, we combined high-resolution and high-precision single zircon U-Pb geochronology. Our data suggest that seafloor spreading has been nearly symmetrical for the last ∼4.6 Myr with a time-averaged half-spreading rate of ∼7.4 mm yr−1. Crystal size analysis of olivine in porphyric intrusions suggests that the crustal section was fed crystal-laden melts with recurrence rates predicted to stabilize fault-dominated seafloor spreading. Our combined geochronological and crystal size approach gives a critical perspective on the mode of seafloor spreading in the Mohns Ridge and allows insights into accretionary mechanisms and crustal structures during symmetric seafloor spreading.

• Ruh, H.L.; Zechmeister, M.; Reiners, A.; Nagel, E.; Shan, Yutong & Cifuentes, C. [Vis alle 22 forfattere av denne artikkelen] (2024). The CARMENES search for exoplanets around M dwarfs: The impact of rotation and magnetic fields on the radial velocity jitter in cool stars. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 692. doi: 10.1051/0004-6361/202450836. Fulltekst i vitenarkiv Vis sammendrag

  Context. Radial velocity (RV) jitter represents an intrinsic limitation on the precision of Doppler searches for exoplanets that can originate from both instrumental and astrophysical sources. Aims. We aim to determine the RV jitter floor in M dwarfs and investigate the stellar properties that lead to RV jitter induced by stellar activity. Methods. We determined the RV jitter in 239 M dwarfs from the CARMENES survey that are predominantly of mid to late spectral type and solar metallicity. We also investigated the correlation between stellar rotation and magnetic fields with RV jitter. Results. The median jitter in the CARMENES sample is 3.1 m s−1, and it is 2.3 m s−1 for stars with an upper limit of 2 km s−1 on their projected rotation velocities. We provide a relation between the stellar equatorial rotation velocity and RV jitter in M dwarfs based on a subsample of 129 well-characterized CARMENES stars. RV jitter induced by stellar rotation dominates for stars with equatorial rotation velocities greater than 1 km s−1. A jitter floor of 2 m s−1 dominates in stars with equatorial rotation velocities below 1 km s−1. This jitter floor likely contains contributions from stellar jitter, instrumental jitter, and undetected companions. We study the impact of the average magnetic field and the distributions of magnetic filling factors on the RV jitter. We find a series of stars with excess RV jitter and distinctive distributions of magnetic filling factors. These stars are characterized by a dominant magnetic field component between 2 to 4 kG. Conclusions. An RV jitter floor can be distinguished from RV jitter induced by activity and rotation based on the stellar equatorial rotation velocity. RV jitter induced by activity and rotation primarily depends on the equatorial rotation velocity. This RV jitter is also related to the distribution of magnetic filling factors, and this emphasizes the role of the magnetic field in the generation of RV jitter.

• Counts, John W.; Vickers, Madeleine Larissa; Stokes, Rebecca; Spivey, Whittney; Gardner, Kristina F. & Self-Trail, Jean M. [Vis alle 16 forfattere av denne artikkelen] (2024). Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska, U.S.A. Journal of Sedimentary Research. ISSN 1527-1404. 94(2), s. 179–206. doi: 10.2110/jsr.2023.060. Fulltekst i vitenarkiv
• Fawdon, Peter; Orgel, Csilla; Adeli, Solmaz; Balme, Matt; Calef, Fred J. & Davis, Joel M. [Vis alle 80 forfattere av denne artikkelen] (2024). The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission. Journal of Maps. 20(1). doi: 10.1080/17445647.2024.2302361. Fulltekst i vitenarkiv Vis sammendrag

  This 1:30,000 scale geological map describes Oxia Planum, Mars, the landing site for the ExoMars Rosalind Franklin rover mission. The map represents our current understanding of bedrock units and their relationships prior to Rosalind Franklin’s exploration of this location. The map details 15 bedrock units organised into 6 groups and 7 textural and surficial units. The bedrock units were identified using visible and near-infrared remote sensing datasets. The objectives of this map are (i) to identify where the most astrobiologically relevant rocks are likely to be found, (ii) to show where hypotheses about their geological context (within Oxia Planum and in the wider geological history of Mars) can be tested, (iii) to inform both the long-term (hundreds of metres to ∼1 km) and the short-term (tens of metres) activity planning for rover exploration, and (iv) to allow the samples analysed by the rover to be interpreted within their regional geological context.

• Weerdesteijn, Maaike Francine Maria & Conrad, Clinton Phillips (2024). Recent ice melt above a mantle plume track is accelerating the uplift of Southeast Greenland. Communications Earth & Environment. 5. doi: 10.1038/s43247-024-01968-6. Fulltekst i vitenarkiv Vis sammendrag

  Around the periphery of the Greenland ice sheet, satellite-based observations of ground uplift record Earth’s response to past and recent unloading of Greenland’s ice mass. On the southeast coast, near the Kangerlussuaq glacier, rapid uplift exceeding 12 mm/yr cannot be explained using current layered Earth deformation models. Here we find that 3D models with a weakened Earth structure, consistent with the passage of Greenland over the Iceland plume, can explain the rapid uplift of Southeast Greenland. This uplift is dominated by a viscous response that is accelerated by the low viscosities of the hot plume track. Recent mass loss, occurring during the last millennium and especially within the past few decades, drives most of the uplift. Holocene indicators recorded similarly rapid uplift following deglaciation that ended the last ice age. Such rapid uplift, occurring beneath marine terminating glaciers, can affect the future stability of entire ice catchment areas and will become increasingly important in the near future as deglaciation accelerates.

• Tonti-Filippini, Justin Antony Dean; Robert, Boris; Muller, Élodie; Paul, André N.; Dellefant, Fabian & Wack, Michael [Vis alle 10 forfattere av denne artikkelen] (2024). Middle Neoproterozoic (Tonian) Polar Wander of South China: Paleomagnetism and ID-TIMS U-Pb Geochronology of the Laoshanya Formation. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 129(4). doi: 10.1029/2023JB027634. Fulltekst i vitenarkiv Vis sammendrag

  Paleomagnetic records of middle Neoproterozoic (820 to 780 Ma) rocks display high amplitude directional variations that lead to large discrepancies in paleogeographic reconstructions. Hypotheses to explain these data include rapid true polar wander (TPW), a geomagnetic field geometry that deviates from a predominantly axial dipole field, a hyper-reversing field (>10 reversals/Ma), and/or undiagnosed remagnetization. To test these hypotheses, we collected 1,057 oriented cores over a 85 m stratigraphic succession in the Laoshanya Formation (Yangjiaping, Hunan, China). High precision U-Pb dating of two intercalated tuff layers constrain the age of the sediments between 809 and 804 Ma. Thermal demagnetization isolates three magnetization components residing in hematite which are not time-progressive but conflated throughout the section. All samples possess a north and downward directed component in geographic coordinates at temperatures up to 660°C that is ascribed to a Cretaceous overprint. Two components isolated above 660°C reveal distinct directional clusters: one is interpreted as a depositional remanence, while the other appears to be the result of a mid-Paleozoic (460 to 420 Ma) remagnetization, which is likely widespread throughout South China. The high-temperature directions are subtly dependent on lithology; microscopic and rock magnetic analyses identify multiple generations of hematite that vary in concentration and distinguish the magnetization components. A comparison with other middle Neoproterozoic paleomagnetic studies in the region indicates that the sudden changes in paleomagnetic directions, used elsewhere to support the rapid TPW hypothesis (ca. 805 Ma), are better explained by mixtures of primary and remagnetized components, and/or vertical axis rotations.

• Abdelmalak, Mohamed Mansour; Polteau, Stephane; Planke, Sverre; Faleide, Jan Inge; Lebedeva-Ivanova, Nina N. & Myklebust, Reidun (2024). NE Canada Rifted Margin Composite Tectono-Sedimentary Element, Baffin Bay, Davis Strait and Labrador Sea. Geological Society of London Memoirs. ISSN 0435-4052. 57(1). doi: 10.1144/M57-2021-44. Fulltekst i vitenarkiv
• Ghail, Richard C.; Smrekar, Suzanne E.; Widemann, Thomas; Byrne, Paul K.; Gülcher, Anna J. P. & O’Rourke, Joseph G. [Vis alle 15 forfattere av denne artikkelen] (2024). Volcanic and Tectonic Constraints on the Evolution of Venus. Space Science Reviews. ISSN 0038-6308. 220. doi: 10.1007/s11214-024-01065-2. Fulltekst i vitenarkiv Vis sammendrag

  Surface geologic features form a detailed record of Venus’ evolution. Venus displays a profusion of volcanic and tectonics features, including both familiar and exotic forms. One challenge to assessing the role of these features in Venus’ evolution is that there are too few impact craters to permit age dates for specific features or regions. Similarly, without surface water, erosion is limited and cannot be used to evaluate age. These same observations indicate Venus has, on average, a very young surface (150–1000 Ma), with the most recent surface deformation and volcanism largely preserved on the surface except where covered by limited impact ejecta. In contrast, most geologic activity on Mars, the Moon, and Mercury occurred in the 1st billion years. Earth’s geologic processes are almost all a result of plate tectonics. Venus’ lacks such a network of connected, large scale plates, leaving the nature of Venus’ dominant geodynamic process up for debate. In this review article, we describe Venus’ key volcanic and tectonic features, models for their origin, and possible links to evolution. We also present current knowledge of the composition and thickness of the crust, lithospheric thickness, and heat flow given their critical role in shaping surface geology and interior evolution. Given Venus’ hot lithosphere, abundant activity and potential analogues of continents, roll-back subduction, and microplates, it may provide insights into early Earth, prior to the onset of true plate tectonics. We explore similarities and differences between Venus and the Proterozoic or Archean Earth. Finally, we describe the future measurements needed to advance our understanding of volcanism, tectonism, and the evolution of Venus.

• Wang, Yijun; Kiraly, Agnes; Conrad, Clinton Phillips; Hansen, Lars & Fraters, Menno (2024). The Importance of Anisotropic Viscosity in Numerical Models, for Olivine Textures in Shear and Subduction Deformations. Tektonika. 2(1), s. 157–173. doi: 10.55575/tektonika2024.2.1.67. Fulltekst i vitenarkiv Vis sammendrag

  Olivine lattice preferred orientation (LPO), or texture, forms in relation to deformation mechanisms such as dislocation creep and can be observed in the upper mantle as seismic anisotropy. Olivine is also mechanically anisotropic, meaning that it responds to stresses differently depending on the direction of the stress. Understanding the interplay between anisotropic viscosity (AV) and LPO, and their role in deformation, is necessary for relating seismic anisotropy to mantle flow patterns. In this study, we employ three methods to predict olivine texture (D-Rex, MDM, and MDM+AV) in a shear box model and a subduction model. D-Rex and MDM are two representative texture development methods that have been compared before, and our results are in line with previous studies showing that textures computed by D-Rex develop faster and are stronger and more point-like than textures calculated with MDM. MDM+AV uses the same isotropic mantle stresses and particle paths as D-Rex and MDM but includes the effect of AV for texture predictions. MDM+AV predicts a texture similar to MDM with a distinct girdle-like orientation for simple shear deformation or at low strain in the subduction model. At larger strains, MDM+AV’s textures are more point-like and stronger compared to the other two methods. The effective viscosity for MDM+AV drops by up to 60% in a shear box model and can be either strengthened or weakened relative to isotropic viscosity for different regions of the subduction model experiencing different patterns of deformation. Our results emphasize the significant role of AV in olivine texture development, which could substantially affect geodynamic processes in the upper mantle.

• Saurety, Adrien; Ozgurel, Ozge; Mohn, Chris Erik & Caracas, Razvan (2024). Diffusion, chemical bonding, and kinetic fractionation of noble gases in the primordial magma ocean. Geochimica et Cosmochimica Acta. ISSN 0016-7037. 378, s. 144–152. doi: 10.1016/j.gca.2024.06.021. Fulltekst i vitenarkiv Vis sammendrag

  Noble gases record in their radiogenic/non-radiogenic isotope ratios the traces of accretion history and degassing events from the early Earth, including giant impacts and the magma ocean stage, to large-scale recent volcanism. The diffusional behavior of noble gases in silicate magmas is one of the essential parameters needed to correctly model devolatilization from the magma ocean and subsequent volcanic eruptions. Here, we study the diffusivity of He, Ne, Ar, Kr, and Xe in molten pyrolite using ab initio molecular dynamics. We find that the diffusivity of the noble gases decreases with increasing atomic size. The diffusion of Ar is comparable to that of Mg. We compute the partial molar volumes and find that at high pressure, He is almost one order of magnitude more compressible than the heavier noble gases. The analysis of the speciation of the noble gases in the melt indicates that the lifetime of the coordination polyhedra formed with O is not sensitive to the mass of the noble gases. Finally, we compute the electron localization function along the Xe–O interatomic vectors and show that there is no chemical bonding between the Xe and surrounding O atoms from the hosting silicate melt.

• Ramirez, Florence; Selway, Katherine; Conrad, Clinton Phillips; Maupin, Valerie & Smirnov, Maxim (2024). Lateral and radial viscosity structure beneath Fennoscandia inferred from seismic and magnetotelluric observations. Physics of the Earth and Planetary Interiors. ISSN 0031-9201. 351. doi: 10.1016/j.pepi.2024.107178. Fulltekst i vitenarkiv Vis sammendrag

  Fennoscandia is continuously uplifting in response to past deglaciation, termed glacial isostatic adjustment or GIA, and its mantle viscosity is well constrained from ice sheet and sea level data. Here, we compare those GIA-constrained viscosities for the Fennoscandian upper mantle with geophysically-constrained viscosities. We construct the upper mantle viscosity structure of Fennoscandia by inferring temperature and water content from seismic and magnetotelluric (MT) data. Using a 1-D MT model for Fennoscandian cratons together with a global seismic model, we infer an upper mantle viscosity (below 250 km) of ∼1021±2 Pa·s, which encompasses the GIA-constrained viscosities of 1020 − 1021 Pa·s. The GIA viscosities are better matched if the Fennoscandian upper mantle is a wet harzburgite or a dry pyrolite, where pyrolite is ∼10 times more viscous than harzburgite. Using the average temperatures and water contents for harzburgitic upper mantle, the GIA viscosities require 1–4 mm grain sizes indicating a diffusion creep regime. In northwestern Fennoscandia, where a high-resolution 2-D resistivity model is available, greater inferred mantle water content implies viscosities that are 10–100 times lower than those for the Fennoscandian Craton. Our work suggests that the combination of seismic and MT observations can improve upper mantle viscosity estimates, especially for regions with laterally-varying viscosity structures or where GIA constraints are not available. Although our method represents an important step forward, viscosity uncertainty can be further reduced by incorporating additional constraints on rock composition, grain size and mantle stress, as well as more accurate geophysical data, into the viscosity calculation.

• Ortiz-Guerrero, Carolina; Montes, Camilo; Farris, David W.; Agudelo, Catalina; Acero, Margarita Ariza & Ayala, Juliana [Vis alle 24 forfattere av denne artikkelen] (2024). Crustal structure of the Western Azuero Peninsula, Panama: Insights into the structure of accretionary complexes and forearc ophiolites. International Geology Review. ISSN 0020-6814. 66(1), s. 172–195. doi: 10.1080/00206814.2023.2191678. Fulltekst i vitenarkiv Vis sammendrag

  Detailed geologic mapping (639 field stations in ~700 km2) and a ~50 km-long gravity survey (142 stations) in the western Azuero Peninsula revealed two faulted and folded slivers of oceanic crust attached to the trailing edge of the Caribbean Large Igneous Plateau (CLIP). Our new data, along with published geochronology, allowed us to reconstruct the Cretaceous forearc configuration of the trailing edge of the CLIP prior to seamount collision, ophiolite accretion, and whole-margin deformation. The ophiolite in western Azuero is composed of two tectonic slivers arranged in south-verging, imbricated thrust faults that stack a ~73 Ma pillow, flow, and picritic basalt and black chert, together with a ~ 89–93 Ma and older basalt flows and capping red chert sequences. Accretion of these slivers to form a supra-subduction zone ophiolite resulted from the middle Eocene collision and accretion of Galapagos seamounts against the trailing edge of the CLIP. Accreted seamounts are arranged in a north-verging antiformal stack duplex, and below the thrust sheets. Change in kinematics after fission of the Cocos-Nazca Plate during early Miocene times prompted the propagation of the Azuero-Sona fault zone flower structure, favouring the preservation of these slivers of oceanic crust.

• Geng, Ming & Mohn, Chris Erik (2024). Ab initio constraints on the melting of silica at high pressures up to 500 GPa. Physical review B (PRB). ISSN 2469-9950. 109. doi: 10.1103/PhysRevB.109.024106. Fulltekst i vitenarkiv
• Heron, Philip J.; Gün, Erkan; Shephard, Grace; Dannberg, Juliane; Gassmöller, R. & Martin, Erin [Vis alle 10 forfattere av denne artikkelen] (2024). The role of subduction in the formation of Pangaean oceanic large igneous provinces. Geological Society of London Memoirs. ISSN 0435-4052. 542(1), s. 105–128. doi: 10.1144/SP542-2023-12. Fulltekst i vitenarkiv Vis sammendrag

  Large igneous provinces (LIPs) have been linked to both surface and deep mantle processes. During the formation, tenure and break-up of the supercontinent Pangaea, there is an increase in emplacement events for both continental and oceanic LIPs. There is currently no clear consensus on the origin of LIPs, but a hypothesis relates their formation to crustal emplacement of hot plume material originating in the deep mantle. The interaction of subducted slabs with the lowermost mantle thermal boundary and subsequent return flow is a key control on such plume generation. This mechanism has been explored for LIPs below the interior of a supercontinent (i.e. continental LIPs). However, a number of LIPs formed exterior to Pangaea (e.g. Ontong Java Plateau), with no consensus on their formation mechanism. Here, we consider the dynamics of supercontinent processes as predicted by numerical models of mantle convection and analyse whether circum-supercontinent subduction could generate both interior (continental) and exterior (oceanic) deep mantle plumes. Our numerical models show that subduction related to the supercontinent cycle can reproduce the location and timing of the Ontong Java Plateau, Caribbean LIP and potentially the Shatsky Rise by linking the origin of these LIPs to the return flow that generated deep mantle exterior plumes.

• Capriolo, Manfredo; Callegaro, Sara; Deegan, Frances M.; Merle, Renaud; Jeon, Heejin & Whitehouse, Martin J. [Vis alle 16 forfattere av denne artikkelen] (2024). Dynamic Evolution of the Transcrustal Plumbing System in Large Igneous Provinces: Geochemical and Microstructural Insights from Glomerocrysts and Melt Inclusions. Journal of Petrology. ISSN 0022-3530. 65(10). doi: 10.1093/petrology/egae103. Fulltekst i vitenarkiv Vis sammendrag

  Objective Cognitive perceptual disruption (CPD) is an emotion regulation mechanism described in intensive short-term dynamic psychotherapy (ISTDP) that distinguishes fragile patients from resistant ones. CPD functions as an involuntary avoidance-based mechanism that prevents engagement with distressing emotions, making its identification crucial for guiding treatment. Currently, CPD assessment relies solely on clinical psychodiagnostic evaluation, with no available psychometric instruments. This study introduces a cognitive perceptual disruption screening instrument (Copeds), a self-report measure designed to identify CPD and assist in treatment planning for emotion-focused therapies. Method A cross-sectional study was conducted to develop Copeds, evaluate its ability to distinguish between fragile and resistant patients, and examine its preliminary psychometric properties. 112 outpatients underwent clinical psychodiagnostic evaluation and completed Copeds. Regularized regression techniques, receiver operating characteristic (ROC) analysis, and analyses of internal consistency and sensitivity/specificity were performed. Results The final instrument contained 19 psychometric items that strongly discriminated between fragile and resistant patients. ROC analysis yielded an area under the curve (AUC) value of 0.88. Sensitivity was 91.4%, and specificity was 76.4%. Conclusion The study provides promising initial evidence for Copeds as a reliable instrument with strong classification accuracy, supporting its potential use in clinical assessment and treatment planning for emotion-focused therapies.

• Tan, Pingchuan; Breivik, Asbjørn; Ding, Weiwei; Zhang, Tao; Niu, Xiongwei & Li, Jiabiao (2024). Unexpectedly High Magma Productivity Inferred From Crustal Roughness and Residual Bathymetry on the Eastern Part of the Ultra-Slow Spreading Gakkel Ridge Since ∼45 Ma, Eurasian Basin, Arctic Ocean. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 129(6). doi: 10.1029/2023JB028470. Fulltekst i vitenarkiv Vis sammendrag

  The Gakkel Ridge in the Eurasian Basin has the slowest seafloor spreading worldwide. The western Gakkel Ridge (3°W–85°E; 14–11 mm/a) alternate between magmatic and sparsely magmatic zones, while the eastern Gakkel Ridge (85–126°E; 11–6 mm/a) appears to be dominated by magmatic zones despite ultraslow spreading. Little is known about the seafloor spreading conditions in the past along the entire ridge. Here, we exploit the residual bathymetry and basement roughness to assess the crustal accretion process of the Gakkel Ridge over time using 23 published regional multichannel seismic reflection profiles. Full seafloor spreading rates were faster (20–24 mm/a) up to ∼45 Ma, and residual bathymetry for the older crust is deeper than the world average in the entire Eurasian Basin. There is a sharp transition to 300–400 m shallower residual bathymetry for seafloor <45 Ma in the eastern Eurasian Basin. The crustal roughness versus spreading rate of the western Eurasian Basin is on the global trend, while that of the eastern is significantly below. Both low roughness and shallow residual bathymetry of the eastern Eurasian Basin is close to that of oceanic crust for spreading rates above 30 mm/a, demonstrating increased magmatic production of the eastern Gakkel Ridge since ∼45 Ma. A recent mantle tomography model predicts partial melting in the upper mantle based on the low Vs anomaly underneath. The sedimentary pattern toward the Lomonosov Ridge indicates that this hot mantle anomaly started to cause dynamic uplift of the area at ∼45 Ma.

• Mamonova, Elena; Shan, Yutong; Hatalova, Petra & Werner, Stephanie C. (2024). Planets similar in size are often dissimilar in interior. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 685. doi: 10.1051/0004-6361/202347049. Fulltekst i vitenarkiv Vis sammendrag

  The number of discovered exoplanets now exceeds 5500 allowing statistical analyses of planetary systems. Multi-planet systems are mini-laboratories of planet formation and evolution, and analysing their system architectures can help us to constrain the physics of these processes. Recent works have found evidence of significant intrasystem uniformity in planet properties such as radius, mass, and orbital spacing, collectively termed ‘peas in a pod’ trends. In particular, correlations in radius and mass have been interpreted as implying uniformity in planet bulk density and composition within a system. However, the samples used to assess trends in mass tend to be small and biased. In this paper, we re-evaluate correlations in planet properties in a large sample of systems with at least two planets for which mass and radius have been directly measured, and therefore bulk density can be calculated. Our sample was assembled using the most up-to-date exoplanet catalogue data, and we compute the relevant statistics while using a procedure to ‘weight’ the data points according to measurement precision. We find a moderate correlation in radius and a weak correlation in the densities of adjacent planets. However, masses of neighbouring planets show no overall correlation in our main sample and a weak correlation among pairs of planets similar in size or pairs restricted to Mp<100 M⊕, Rp<10 R⊕. Similarly, we show that the intrasystem dispersion in radius is typically less than that in mass and density. We identify ranges in stellar host properties that correlate with stronger uniformity in pairs of adjacent planets: low Teff for planet masses, and low metallicity and old age for planet densities. Furthermore, we explore whether peas in a pod trends extend into planet compositions or interior structures. For small neighbouring planets with similar radii, we show that their masses and interior structures are often disparate, indicating that even within the same system, similarity in radii is not necessarily a good proxy for similarity in composition or the physical nature of the planets.

• Galland, Olivier; Villar, Héctor J.; Mescua, José; Jerram, Dougal Alexander; Messager, Gregoire Eugene Philippe & Medialdea, Adrian [Vis alle 11 forfattere av denne artikkelen] (2024). Structural control of igneous intrusions on fluid migration in sedimentary basins: the case study of large bitumen seeps at Cerro Alquitrán and Cerro La Paloma, northern Neuquén Basin, Argentina. Geological Society Special Publication. ISSN 0305-8719. 547(1), s. 231–259. doi: 10.1144/SP547-2023-115. Fulltekst i vitenarkiv
• Heuser, Ben; Bergermann, Armin; Stevenson, Michael G.; Ranjan, Divyanshu; He, Zhiyu & Lütgert, Julian [Vis alle 40 forfattere av denne artikkelen] (2024). Release dynamics of nanodiamonds created by laser-driven shock-compression of polyethylene terephthalate. Scientific Reports. 14. doi: 10.1038/s41598-024-62367-7. Fulltekst i vitenarkiv Vis sammendrag

  Laser-driven dynamic compression experiments of plastic materials have found surprisingly fast formation of nanodiamonds (ND) via X-ray probing. This mechanism is relevant for planetary models, but could also open efficient synthesis routes for tailored NDs. We investigate the release mechanics of compressed NDs by molecular dynamics simulation of the isotropic expansion of finite size diamond from different P-T states. Analysing the structural integrity along different release paths via molecular dynamic simulations, we found substantial disintegration rates upon shock release, increasing with the on-Hugnoiot shock temperature. We also find that recrystallization can occur after the expansion and hence during the release, depending on subsequent cooling mechanisms. Our study suggests higher ND recovery rates from off-Hugoniot states, e.g., via double-shocks, due to faster cooling. Laser-driven shock compression experiments of polyethylene terephthalate (PET) samples with in situ X-ray probing at the simulated conditions found diamond signal that persists up to 11 ns after breakout. In the diffraction pattern, we observed peak shifts, which we attribute to thermal expansion of the NDs and thus a total release of pressure, which indicates the stability of the released NDs.

• Charnoz, Sébastien; Falco, Aurélien; Tremblin, Pascal; Sossi, Paolo; Caracas, Razvan & Lagage, Pierre-Olivier (2023). The effect of a small amount of hydrogen in the atmosphere of ultrahot magma-ocean planets: Atmospheric composition and escape. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 674. doi: 10.1051/0004-6361/202245763. Fulltekst i vitenarkiv Vis sammendrag

  Context. Ultrahot (&gt;1500 K) rocky exoplanets may be covered by a magma ocean, resulting in the formation of a vapor rich in rocky components (e.g., Mg, Si, Fe) with a low total pressure and high molecular mass. However, exoplanets may have also captured a significant amount of hydrogen from the nebular gas during their formation. Ultrahot rocky exoplanets around the Fulton gap (~1.8 R ⊕ ) are sufficiently large to have retained some fraction of their primordial hydrogen atmosphere. Aims. Here, we investigate how small amounts of hydrogen (much smaller than the mass of the planet) above a magma ocean may modify the atmospheric chemistry and its tendency to thermally escape. Methods. We use a chemical model of a magma ocean coupled to a gas equilibrium code (that includes hydrogen) to compute the atmospheric composition at thermodynamical equilibrium for various H contents and temperatures. An energy-limited model is used to compute atmospheric escape and is scaled to consider H-rich and H-poor atmospheres. Results. The composition of the vapor above a magma ocean is drastically modified by hydrogen, even for very modest amounts of H (≪10 −6 planetary mass). Hydrogen consumes much of the O 2 (g), which, in turn, promotes the evaporation of metals and metal oxides (SiO, Mg, Na, K, Fe) from the magma ocean. Vast amounts of H 2 O are produced by the same process. At high hydrogen pressures, new hydrogenated species such as SiH 4 form in the atmosphere. In all cases, H, H 2 , and H 2 O are the dominant nonmetal-bearing volatile species. Sodium is the dominant atmospheric metal-bearing species at T &lt; 2000 K and low H content, whereas Fe is dominant at high H content and low temperature, while SiO predominates at T &gt; 3000 K. We find that the atmospheric Mg/Fe, Mg/Si, and Na/Si ratios deviate from those in the underlying planet and from the stellar composition. As such, their determination may constrain the planet’s mantle composition and H content. As the presence of hydrogen promotes the evaporation of silicate mantles, it is conceivable that some high-density, irradiated exoplanets may have started life as hydrogen-bearing planets and that part of their silicate mantle evaporated (up to a few 10% of Si, O, and Fe) and was subsequently lost owing to the reducing role of H. Conclusions. Even very small amounts of H can alter the atmospheric composition and promote the evaporation to space of heavy species derived from the molten silicate mantle of rocky planets. Through transit spectroscopy, the measurement of certain elemental ratios, along with the detection of atmospheric water or hydrogen, may help to determine the nature of a surface magma ocean.

• Callegaro, Sara; Baker, Don R.; Renne, Paul R.; Melluso, Leone; Geraki, Kalotina & Whitehouse, Martin J. [Vis alle 8 forfattere av denne artikkelen] (2023). Recurring volcanic winters during the latest Cretaceous: Sulfur and fluorine budgets of Deccan Traps lavas. Science Advances. 9(40). doi: 10.1126/sciadv.adg8284. Fulltekst i vitenarkiv Vis sammendrag

  Two events share the stage as main drivers of the Cretaceous-Paleogene mass extinction—Deccan Traps volcanism, and an asteroid impact recorded by the Chicxulub crater. We contribute to refining knowledge of the volcanic stressor by providing sulfur and fluorine budgets of Deccan lavas from the Western Ghats (India), which straddle the Cretaceous-Paleogene boundary. Volcanic fluorine budgets were variable (400 to 3000 parts per million) and probably sufficient to affect the environment, albeit only regionally. The highest sulfur budgets (up to 1800 parts per million) are recorded in Deccan lavas emplaced just prior (within 0.1 million years) to the extinction interval, whereas later basalts are generally sulfur-poor (up to 750 parts per million). Independent evidence suggests the Deccan flood basalts erupted in high-flux pulses. Our data suggest that volcanic sulfur degassing from such activity could have caused repeated short-lived global drops in temperature, stressing the ecosystems long before the bolide impact delivered its final blow at the end of the Cretaceous.

• Ontiveros, Daniel Eliahou; Beaugrand, Gregory; Lefebvre, Bertrand; Marcilly, Chloe M.; Servais, Thomas & Pohl, Alexandre (2023). Impact of global climate cooling on Ordovician marine biodiversity. Nature Communications. 14. doi: 10.1038/s41467-023-41685-w. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Global cooling has been proposed as a driver of the Great Ordovician Biodiversification Event, the largest radiation of Phanerozoic marine animal Life. Yet, mechanistic understanding of the underlying pathways is lacking and other possible causes are debated. Here we couple a global climate model with a macroecological model to reconstruct global biodiversity patterns during the Ordovician. In our simulations, an inverted latitudinal biodiversity gradient characterizes the late Cambrian and Early Ordovician when climate was much warmer than today. During the Mid-Late Ordovician, climate cooling simultaneously permits the development of a modern latitudinal biodiversity gradient and an increase in global biodiversity. This increase is a consequence of the ecophysiological limitations to marine Life and is robust to uncertainties in both proxy-derived temperature reconstructions and organism physiology. First-order model-data agreement suggests that the most conspicuous rise in biodiversity over Earth’s history – the Great Ordovician Biodiversification Event – was primarily driven by global cooling.

• Krzesinska, Agata Magdalena; Tymiñski, Zbigniew & Maækowska, Roksana (2023). The Antonin Chondrite - the first Polish meteorite with reconstructed pre-atmospheric orbit. Report on registration and classification, including proposals for measures to expand the Polish meteorite collection. Przeglad Geologiczny. ISSN 0033-2151. 71(7), s. 372–385. doi: 10.7306/2023.33. Fulltekst i vitenarkiv
• Domeier, Mathew Michael; Robert, Boris; Meert, Joseph G.; Kulakov, Evgeniy; McCausland, Phil J.A. & Trindade, Ricardo I.F. [Vis alle 7 forfattere av denne artikkelen] (2023). The enduring Ediacaran paleomagnetic enigma. Earth-Science Reviews. ISSN 0012-8252. 242. doi: 10.1016/j.earscirev.2023.104444. Fulltekst i vitenarkiv Vis sammendrag

  The Ediacaran Period was an interval of significant global transformation, marked by major changes in the biosphere, cryosphere, hydrosphere and atmosphere, and possibly the solid Earth. A better understanding of this interval is thus important to an understanding of the diversification of complex life, the history of long-term climatic change and the evolution of global geochemical cycles. Increasingly detailed temporal records are being acquired from Ediacaran rocks to investigate these changes in time, but we still lack a robust paleogeographic framework to study them in space. Paleomagnetic data—which are used to quantitatively determine the ancient position of continents—appear unusually complex and often contradictory throughout this period. The nature of these complex data remains elusive and four distinct hypotheses have been forwarded to explain them: 1) the tectonic plates were moving especially fast, 2) many of the paleomagnetic data have been corrupted in some as-yet unrecognized way, 3) the solid Earth underwent rapid bouts of true polar wander, or 4) the magnetic field was behaving abnormally. Each of these hypotheses have far-reaching implications. Hypotheses 1, 3 and 4 reflect processes which differ dramatically from their present-day counterparts and defy prevailing paradigms of secular change, whereas hypothesis 2 raises questions about the reliability of existing paleomagnetic interpretations and their paleogeographic derivatives. Significant advances will be garnered through resolution of this enigma, but its endurance reflects its intricacy, and any solution is going to require a collective effort. With the aim to stimulate additional community efforts toward solving it, we probe these multiple working hypotheses, elaborate how they may be further tested and discuss the implications of their possible validation.

• Ruggiero, L.; Sciarra, A.; Mazzini, Adriano; Florindo, F.; Wilson, G. & Tartarello, M. C. [Vis alle 13 forfattere av denne artikkelen] (2023). Antarctic permafrost degassing in Taylor Valley by extensive soil gas investigation. Science of the Total Environment. ISSN 0048-9697. 866. doi: 10.1016/j.scitotenv.2022.161345. Fulltekst i vitenarkiv
• González-Álvarez, E.; Kemmer, J.; Chaturvedi, P.; Caballero, J.A.; Quirrenbach, A. & Amado, P.J. [Vis alle 32 forfattere av denne artikkelen] (2023). The CARMENES search for exoplanets around M dwarfs: A sub-Neptunian mass planet in the habitable zone of HN Lib. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202346276. Fulltekst i vitenarkiv Vis sammendrag

  We report the discovery of HN Lib b, a sub-Neptunian mass planet orbiting the nearby ( d ≈ = 6.25 pc) M4.0 V star HN Lib detected by our CARMENES radial-velocity (RV) survey. We determined a planetary minimum mass of M b sin i = 5.46 ± 0.75 M ⊕ and an orbital period of P b = 36.116 ± 0.029 d, using ~5 yr of CARMENES data, as well as archival RVs from HARPS and HIRES spanning more than 13 yr. The flux received by the planet equals half the instellation on Earth, which places it in the middle of the conservative habitable zone (HZ) of its host star. The RV data show evidence for another planet candidate with M [c] sin i = 9.7 ± 1.9 M ⊕ and P [c] = 113.46 ± 0.20 d. The long-term stability of the signal and the fact that the best model for our data is a two-planet model with an independent activity component stand as strong arguments for establishing a planetary origin. However, we cannot rule out stellar activity due to its proximity to the rotation period of HN Lib, which we measured using CARMENES activity indicators and photometric data from a ground-based multi-site campaign as well as archival data. The discovery adds HN Lib b to the shortlist of super-Earth planets in the habitable zone of M dwarfs, but HN Lib [c] probably cannot be inhabited because, if confirmed, it would most likely be an icy giant.

• Panea, Ionelia; Munteanu, Ioan; Gaina, Carmen; Mocanu, Victor; Roban, Relu Dumitru & Bouaru, Catalin Florin (2023). Miocene tectonic activity at the boundary between NE Pannonian and NW Transylvanian basins (Romania): Insight from new seismic data. Terra Nova. ISSN 0954-4879. 35(6), s. 542–551. doi: 10.1111/ter.12677. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Situated at the junction between the Eastern Carpathians Mountains, the Pannonian and the Transylvanian basins, the Baia Mare region (Romania) has a complex geological history that witnessed the interaction among the three main tectonic provinces. Here, we report results from new seismic reflection measurements that provide modern information about the subsurface geological structure. The integrated analysis of the newly acquired and vintage seismic reflection data from the study area reveals details about the architecture of the Palaeogene and the Neogene deposits at the contact between the northeastern Pannonian and northwestern Transylvanian basins. In particular, it unveils a fault zone that most probably controlled the tectonic evolution of the eastern Pannonian and Transylvanian basins. A better understanding of the crustal structure and tectonic features in the study area is a first step into evaluating the geothermal potential of the region.

• Langet, Nadege & Silverberg, Fred Marcus John (2023). Automated classification of seismic signals recorded on the Åknes rock slope, Western Norway, using a convolutional neural network. Earth Surface Dynamics. ISSN 2196-6311. 11(1), s. 89–115. doi: 10.5194/esurf-11-89-2023. Fulltekst i vitenarkiv Vis sammendrag

  Abstract. A convolutional neural network (CNN) was implemented to automatically classify 15 years of seismic signals recorded by an eight-geophone network installed around the back scarp of the Åknes rock slope in Norway. Eight event classes could be identified and are adapted from the typology proposed by Provost et al. (2018), of which five could be directly related to movements on the slope. Almost 60 000 events were classified automatically based on their spectrogram images. The performance of the classifier is estimated to be near 80 %. The statistical analysis of the results shows a strong seasonality of the microseismic activity at Åknes with an annual increase in springtime when snow melts and the temperature oscillates around the freezing point, mainly caused by events within classes of low-frequency slope quakes and tremors. The clear link between annual temperature variations and microseismic activity could be confirmed, supporting thawing and freezing processes as the origins. Other events such as high-frequency and successive slope quakes occur throughout the year and are potentially related to the steady creep of the sliding plane. The huge variability in the annual event number cannot be solely explained by average temperatures or varying detectability of the network. Groundwater recharge processes and their response to precipitation episodes are known to be a major factor of sliding at Åknes, but the relationship with microseismic activity is less obvious and could not be demonstrated.

• Gorrini, P.; Kemmer, J.; Dreizler, S.; Burn, R.; Hirano, T. & Pozuelos, F.J. [Vis alle 39 forfattere av denne artikkelen] (2023). Planetary companions orbiting the M dwarfs GJ 724 and GJ 3988: A CARMENES and IRD collaboration. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 680. doi: 10.1051/0004-6361/202347108. Fulltekst i vitenarkiv Vis sammendrag

  We report the discovery of two exoplanets around the M dwarfs GJ 724 and GJ 3988 using the radial velocity (RV) method. We obtained a total of 153 3.5 m Calar Alto/CARMENES spectra for both targets and measured their RVs and activity indicators. We also added archival ESO/HARPS data for GJ 724 and infrared RV measurements from Subaru/IRD for GJ 3988. We searched for periodic and stable signals to subsequently construct Keplerian models, considering different numbers of planets, and we selected the best models based on their Bayesian evidence. Gaussian process (GP) regression was included in some models to account for activity signals. For both systems, the best model corresponds to one single planet. The minimum masses are 10.75 −0.87 +0.96 and 3.69 −0.41 +0.42 Earth-masses for GJ 724 b and GJ 3988 b, respectively. Both planets have short periods ( P &lt; 10 d) and, therefore, they orbit their star closely ( a &lt; 0.05 au). GJ 724 b has an eccentric orbit ( e = 0.577 −0.052 +0.055 ), whereas the orbit of GJ 3988 b is circular. The high eccentricity of GJ 724 b makes it the most eccentric single exoplanet (to this date) around an M dwarf. Thus, we suggest a further analysis to understand its configuration in the context of planetary formation and architecture. In contrast, GJ 3988 b is an example of a common type of planet around mid-M dwarfs.

• Hernandez, Jean-Alexis; Bethkenhagen, M.; Ninet, S.; French, M.; Benuzzi-Mounaix, A. & Datchi, F. [Vis alle 12 forfattere av denne artikkelen] (2023). Melting curve of superionic ammonia at planetary interior conditions. Nature Physics. ISSN 1745-2473. 19, s. 1280–1285. doi: 10.1038/s41567-023-02074-8. Fulltekst i vitenarkiv
• Kabanov, Pavel; Hauck, Tyler E.; Gouwy, Sofie A.; Grasby, Stephen E. & Boon, Annique van der (2023). Oceanic anoxic events, photic-zone euxinia, and controversy of sea-level fluctuations during the Middle-Late Devonian. Earth-Science Reviews. ISSN 0012-8252. 241. doi: 10.1016/j.earscirev.2023.104415. Fulltekst i vitenarkiv
• Timmermann, Anina; Shan, Yutong; Reiners, Ansgar & Pack, Andreas (2023). Revisiting equilibrium condensation and rocky planet compositions: Introducing the ECCO PLANETS code. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 676. doi: 10.1051/0004-6361/202244850. Fulltekst i vitenarkiv Vis sammendrag

  Context . The bulk composition of exoplanets cannot yet be directly observed. Equilibrium condensation simulations help us better understand the composition of the planets’ building blocks and their relation to the composition of their host star. Aims . We introduce ECCO PLANETS , an open-source Python code that simulates condensation in the protoplanetary disk. Our aim is to analyse how well a simplistic model can reproduce the main characteristics of rocky planet formation. For this purpose, we revisited condensation temperatures ( T c ) as a means to study disk chemistry, and explored their sensitivity to variations in pressure ( p ) and elemental abundance pattern. We also examined the bulk compositions of rocky planets around chemically diverse stars. Methods . Our T - p -dependent chemical equilibrium model is based on a Gibbs free energy minimisation. We derived condensation temperatures for Solar System parameters with a simulation limited to the most common chemical species. We assessed their change (∆ T c ) as a result of p -variation between 10 −6 and 0.1 bar. To analyse the influence of the abundance pattern, key element ratios were varied, and the results were validated using solar neighbourhood stars. To derive the bulk compositions of planets, we explored three different planetary feeding-zone (FZ) models and compared their output to an external n -body simulation. Results . Our model reproduces the external results well in all tests. For common planet-building elements, we derive a T c that is within ±5 K of literature values, taking a wider spectrum of components into account. The T c is sensitive to variations in p and the abundance pattern. For most elements, it rises with p and metallicity. The tested pressure range (10 −6 − 0.1 bar) corresponds to ∆ T c ≈ +350 K, and for −0.3 ≤ [M/H] ≤ 0.4 we find ∆ T c ≈ +100 K. An increase in C/O from 0.1 to 0.7 results in a decrease of ∆ T c ≈ −100 K. Other element ratios are less influential. Dynamic planetary accretion can be emulated well with any FZ model. Their width can be adapted to reproduce gradual changes in planetary composition.

• Austrheim, Håkon Olaf & Andersen, Torgeir Bjørge (2023). Extreme enrichment of arsenic and antimony during alteration of serpentinized peridotites to form listvenite-like dolomite–quartz rocks and Ni–Cr-rich jasper and quartzites in the Highland Border Complex of Scotland. Journal of the Geological Society. ISSN 0016-7649. 180(5). doi: 10.1144/jgs2023-054. Fulltekst i vitenarkiv Vis sammendrag

  Alteration of serpentinised peridotitesof Highland Border Complex in Scotland took place in two steps. Listvenite-like dolomite-quartz rocks formed by addition of CaO, Sr and CO2 at constant MgO and SiO2 involving a mass increase of ca. 140 %. Stage-two involved the dissolution of dolomite evinced by the abundant pores and rhombohedral-shaped grains of quartz to form Cr- and Ni-rich jasper and quartzites. Formation of the jasper-quartzites involve a mass reduction of ca. 80%. The listvenite-like and jasper-quartzite rocks have enrichment in ACCEPTED MANUSCRIPT the fluid mobile elements Ba, Sr, Cs, As and Sb. The As is present in the Aluminium- Phosphate-Sulphate group of minerals formed during alteration of Cr-spinel. Cr-spinel also alters to porous hematite and ferrihydrite with patches containing up to 5.5 wt% As2O3. Enrichment of As, related to alteration of chromite, is previously unknown from natural rocks, but strongly resembles efficient methods used for remediation of this toxic element. Formation of quartzite and jasper from peridotite and their common presence as pebbles both in the Devonian Old Red conglomerates, in the Highland Border Complex and in Devonian Basins in the Scandinavian Caledonides, highlights their importance and potential for provenance- and tectono-stratigraphic correlations.

• Weerdesteijn, Maaike Francine Maria; Naliboff, John B.; Conrad, Clinton Phillips; Reusen, Jesse M.; Steffen, Rebekka & Heister, Timo [Vis alle 7 forfattere av denne artikkelen] (2023). Modeling Viscoelastic Solid Earth Deformation Due To Ice Age and Contemporary Glacial Mass Changes in ASPECT. Geochemistry Geophysics Geosystems. 24(3). doi: 10.1029/2022GC010813. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The redistribution of past and present ice and ocean loading on Earth's surface causes solid Earth deformation and geoid changes, known as glacial isostatic adjustment. The deformation is controlled by elastic and viscous material parameters, which are inhomogeneous in the Earth. We present a new viscoelastic solid Earth deformation model in ASPECT (Advanced Solver for Problems in Earth's ConvecTion): a modern, massively parallel, open‐source finite element code originally designed to simulate convection in the Earth's mantle. We show the performance of solid Earth deformation in ASPECT and compare solutions to TABOO, a semianalytical code, and Abaqus, a commercial finite element code. The maximum deformation and deformation rates using ASPECT agree within 2.6% for the average percentage difference with TABOO and Abaqus on glacial cycle (∼100 kyr) and contemporary ice melt (∼100 years) timescales. This gives confidence in the performance of our new solid Earth deformation model. We also demonstrate the computational efficiency of using adaptively refined meshes, which is a great advantage for solid Earth deformation modeling. Furthermore, we demonstrate the model performance in the presence of lateral viscosity variations in the upper mantle and report on parallel scalability of the code. This benchmarked code can now be used to investigate regional solid Earth deformation rates from ice age and contemporary ice melt. This is especially interesting for low‐viscosity regions in the upper mantle beneath Antarctica and Greenland, where it is not fully understood how ice age and contemporary ice melting contribute to geodetic measurements of solid Earth deformation.

• Looser, Nathan; Petschnig, Paul; Hemingway, Jordon D.; Fernandez, Alvaro; Grafulha, Luiz Morales & Perez-Huerta, Alberto [Vis alle 10 forfattere av denne artikkelen] (2023). Thermally-induced clumped isotope resetting in belemnite and optical calcites: Towards material-specific kinetics. Geochimica et Cosmochimica Acta. ISSN 0016-7037. 350, s. 1–15. doi: 10.1016/j.gca.2023.03.030. Fulltekst i vitenarkiv Vis sammendrag

  The application of carbonate clumped isotope (Δ47) thermometry in deep-time is often limited by modification of the original temperature signal by thermal resetting. New modeling approaches to estimate the initial isotopic composition of partially reset calcites and maximal burial temperatures, however, open promising avenues in temperature reconstruction. Such approaches strongly depend on laboratory-derived kinetic parameters of calcite materials, which may differ in their microstructure, water content and distribution, and minor and trace element composition, and thus may have different resetting kinetics. The rostra of belemnites, an extinct group of mollusks with a wide temporal and spatial occurrence in the Mesozoic, have been extensively used for deep-time paleoclimate reconstructions using oxygen isotope geochemistry. Belemnites are also important targets for clumped isotope-based temperature reconstructions, but often are found to have reset Δ47 compositions. Here, we present results from heating experiments on belemnite rostral calcite and optical calcite and provide belemnite-specific kinetic parameters for clumped isotope resetting. We show that belemnite calcite is altered faster and at lower temperatures than optical calcite and all other calcites reported in previous studies. We suggest that fast initial resetting results from oxygen isotope exchange of belemnite calcite with internal skeletal water present as fluid inclusions or organic-derived water, a process completed within 2–4 min at the experimental temperatures used here. Extrapolation to geological timescales using different solid-state bond reordering models shows that belemnite calcite resetting starts at lower burial temperatures than brachiopod, spar, and optical calcites. This susceptibility to thermal resetting results in a measurable (+3 °C) increase of the apparent Δ47 temperature even under shallow to moderate burial conditions (i.e., 40–50 °C for 106–107 years timescales). Following the overprint to higher apparent Δ47 temperatures during burial, the belemnite Δ47 may further re-equilibrate during exhumation resulting in a decrease of apparent Δ47 temperatures. Such “retrograde resetting” is similar to what is observed for carbonatites and marbles during cooling, and may cause underestimation of the thermal resetting a sample experienced during its geological history. Overall, our results demonstrate the importance of material-specific kinetic parameters and we urge caution when interpreting Δ47-derived temperatures of biogenic carbonates from deep-time archives.

• Wei, Bitian; Cheng, Xin; Domeier, Mathew Michael; Zhou, Yanan; Chen, Qinglong & Jiang, Nan [Vis alle 12 forfattere av denne artikkelen] (2023). Paleomagnetism of Late Triassic Volcanic Rocks From the South Qiangtang Block, Tibet: Constraints on Longmuco-Shuanghu Ocean Closure in the Paleo-Tethys Realm. Geophysical Research Letters. ISSN 0094-8276. 50(19). doi: 10.1029/2023GL104759. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The South Qiangtang block of the Qinghai‐Tibet Plateau represents an area critical to understanding the late Paleozoic and early Mesozoic history of the Tethyan realm, but its drift history remains poorly constrained. Here we report a new quantitative paleogeographic constraint for the South Qiangtang block from a paleomagnetic study of Late Triassic volcanic rocks of the Xiaoqiebao Formation. A characteristic remanent magnetization isolated from 25 sites passes both fold‐ and reversal tests, and likely represents a primary magnetization. On the basis of these data, we estimate that the South Qiangtang block occupied a paleolatitude of 30.1 ± 4.6°N at ca. 222 Ma. When combined with existing paleomagnetic constraints, these new results indicate that the South Qiangtang block (and other “Cimmerian” blocks) moved rapidly northward (in true latitude) between the middle Permian and Late Triassic. Our new data further suggest that the southern branch of the Paleo‐Tethys (Longmuco‐Shuanghu Ocean) likely closed by the mid‐Late Triassic.

• Widemann, Thomas; Smrekar, Suzanne E.; Garvin, James B.; Straume-Lindner, Anne Grete; Ocampo, Adriana C. & Schulte, Mitchell D. [Vis alle 45 forfattere av denne artikkelen] (2023). Venus Evolution Through Time: Key Science Questions, Selected Mission Concepts and Future Investigations. Space Science Reviews. ISSN 0038-6308. 219. doi: 10.1007/s11214-023-00992-w. Fulltekst i vitenarkiv Vis sammendrag

  Abstract In this work we discuss various selected mission concepts addressing Venus evolution through time. More specifically, we address investigations and payload instrument concepts supporting scientific goals and open questions presented in the companion articles of this volume. Also included are their related investigations (observations &amp; modeling) and discussion of which measurements and future data products are needed to better constrain Venus’ atmosphere, climate, surface, interior and habitability evolution through time. A new fleet of Venus missions has been selected, and new mission concepts will continue to be considered for future selections. Missions under development include radar-equipped ESA-led EnVision M5 orbiter mission (European Space Agency 2021), NASA-JPL’s VERITAS orbiter mission (Smrekar et al. 2022a), NASA-GSFC’s DAVINCI entry probe/flyby mission (Garvin et al. 2022a). The data acquired with the VERITAS, DAVINCI, and EnVision from the end of this decade will fundamentally improve our understanding of the planet’s long term history, current activity and evolutionary path. We further describe future mission concepts and measurements beyond the current framework of selected missions, as well as the synergies between these mission concepts, ground-based and space-based observatories and facilities, laboratory measurements, and future algorithmic or modeling activities that pave the way for the development of a Venus program that extends into the 2040s (Wilson et al. 2022).

• Buffan, Lucas; Jones, Lewis A.; Domeier, Mathew Michael; Scotese, Christopher R.; Zahirovic, Sabin & Varela, Sara (2023). Mind the uncertainty: Global plate model choice impacts deep-time palaeobiological studies. Methods in Ecology and Evolution. 14(12), s. 3007–3019. doi: 10.1111/2041-210X.14204. Fulltekst i vitenarkiv Vis sammendrag

  Global plate models (GPMs) aim to reconstruct the tectonic evolution of the Earth by modelling the motion of the plates and continents through time. These models enable palaeobiologists to study the past distribution of extinct organisms. However, different GPMs exist that vary in their partitioning of the Earth's surface and the modelling of continental motions. Consequently, the preferred use of one GPM will influence palaeogeographic reconstruction of fossil occurrences and any inferred palaeobiological and palaeoclimatic conclusion. Here, using five open-access GPMs, we reconstruct the palaeogeographic distribution of cell centroids from a global hexagonal grid and quantify palaeogeographic uncertainty across the entire Phanerozoic (540–0 Ma). We measure uncertainty between reconstructed coordinates using two metrics: (1) palaeolatitudinal standard deviation and (2) mean pairwise geodesic distance. Subsequently, we evaluate the impact of GPM choice on palaeoclimatic reconstructions when using fossil occurrence data. To do so, we use two climatically sensitive entities (coral reefs and crocodylomorphs) to infer the palaeolatitudinal extent of subtropical climatic conditions for the last 240 million years. Our results indicate that differences between GPMs increase with the age of reconstruction. Specifically, cell centroids rotated to older intervals show larger differences in palaeolatitude and geographic spread than those rotated to younger intervals. However, high palaeogeographic uncertainty is also observed in younger intervals within tectonically complex regions (i.e. in the vicinity of terrane and plate boundaries). We also show that when using fossil data to infer the distribution of subtropical climatic conditions across the last 240 Ma, estimates vary by 6–7° latitude on average, and up to 24° latitude in extreme cases. Our findings confirm that GPM choice is an important consideration when studying past biogeographic patterns and palaeoclimatic trends. We recommend using GPMs that report true palaeolatitudes (i.e. use a palaeomagnetic reference frame) and incorporating palaeogeographic uncertainty into palaeobiological analyses.

• Caracas, Razvan & Stewart, Sarah T. (2023). No magma ocean surface after giant impacts between rocky planets. Earth and Planetary Science Letters. ISSN 0012-821X. 608. doi: 10.1016/j.epsl.2023.118014. Fulltekst i vitenarkiv
• Zertani, Sascha; Menegon, Luca; Pennacchioni, Giorgio; Buisman, Iris; Corfu, Fernando & Jamtveit, Bjørn (2023). Protracted localization of metamorphism and deformation in a heterogeneous lower-crustal shear zone. Journal of Structural Geology. ISSN 0191-8141. 176. doi: 10.1016/j.jsg.2023.104960. Fulltekst i vitenarkiv Vis sammendrag

  Deformation of the continental crust is influenced by the pre-existing structural framework, fluid availability, strain rate, and pressure-temperature conditions. We investigate the evolution of a large (hundreds-of-meters wide) heterogeneous shear zone and associated brittle and ductile deformation structures (Lofoten, Norway) using structural analysis, mineral-chemical and microstructural observations, and U-Pb dating. The shear zone developed through a sequence of metamorphic stages: (1) migmatization and granulite-facies metamorphism, (2) eclogite-facies metamorphism, and (3) amphibolite-facies metamorphism. Stage (1) was related to magmatic activity at lower-crustal conditions prior to 1.7 Ga. Stage (2) likely occurred during the early phases of the collision between Baltica and Laurentia (Caledonian collision). Stage (3) was related to shortening during the main phase of the Caledonian collision (∼430–400 Ma) and was accompanied by hydration of the shear zone. We demonstrate how mechanical heterogeneities influence the deformation style from the centimeter to meter scale. Zones with a pre-existing fabric deformed by ductile shearing and folding, whereas homogeneous, dry rocks fractured. Fractures provided precursors for small-scale shear zones. These contrasting deformation styles occurred repeatedly. Consequently, pre-existing structures define the deformation style and serve as conduits for the channelization of fluids over extended periods of time.

• Prieur, Nils Charles; Amaro, Brian; Gonzalez, Emiliano; Kerner, Hannah; Medvedev, Sergei & Rubanenko, Lior [Vis alle 10 forfattere av denne artikkelen] (2023). Automatic Characterization of Boulders on Planetary Surfaces From High-Resolution Satellite Images. Journal of Geophysical Research (JGR): Planets. ISSN 2169-9097. 128(11). doi: 10.1029/2023JE008013. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Boulders form from a variety of geological processes, which their size, shape, and orientation may help us better understand. Furthermore, they represent potential hazards to spacecraft landing that need to be characterized. However, mapping individual boulders across vast areas is extremely labor‐intensive, often limiting the extent over which they are characterized and the statistical robustness of obtained boulder morphometrics. To automate boulder characterization, we use an instance segmentation neural network, Mask R‐CNN, to detect and outline boulders in high‐resolution satellite and aerial images. Our neural network, BoulderNet, was trained from a data set of &gt;33,000 boulders in &gt;750 image tiles from Earth, the Moon, and Mars. BoulderNet not only correctly detects the majority of boulders in images but also identifies the outline of boulders with high fidelity, achieving average precision and recall values of 72% and 64% relative to manually digitized boulders from the test data set, when only detections with intersection‐over‐union ratios &gt;50% are considered valid. These values are similar to those obtained from human mappers. On Earth, equivalent boulder diameters, aspect ratios, and orientations extracted from predictions were benchmarked against ground measurements and yield values within ±15%, ±0.20, and ±20° of their ground‐truth values, respectively. BoulderNet achieves better boulder detection and characterization performance relative to existing methods, providing a versatile open‐source tool to characterize entire boulder fields on planetary surfaces.

• Koehl, Jean-Baptiste P.; Christophersen, Gard; Collombin, Maxime; Taule, Christoffer; Stokmo, Eirik M. B. & Allaart, Lis (2023). Devonian-Mississippian faulting controlled by WNW-ESE-striking structural grain in Proterozoic basement rocks in Billefjorden, central Spitsbergen. Geologica Acta. ISSN 1695-6133. 21. doi: 10.1344/GeologicaActa2023.21.7. Fulltekst i vitenarkiv
• Bristol, K.E.; Smirnov, A.V.; Piispa, E.J.; Navas, M.R. Ramirez; Kosterov, A. & Kulakov, Evgeniy (2023). Magnetic characterization of the Daule chondrite (Ecuador's first meteorite fall): The case of elusive tetrataenite? Icarus (New York, N.Y. 1962). ISSN 0019-1035. 404. doi: 10.1016/j.icarus.2023.115684. Fulltekst i vitenarkiv
• Farsang, Stefan; Caracas, Razvan; Adachi, Takuji B.M.; Schnyder, Cédric & Zajacz, Zoltán (2023). S ·<inf>3</inf>radicals and the S·²<inf>4</inf>polysulfide ion in lazurite, haöyne, and synthetic ultramarine blue revealed by resonance Raman spectroscopy. American Mineralogist. ISSN 0003-004X. 108(12), s. 2234–2243. doi: 10.2138/am-2022-8655. Fulltekst i vitenarkiv
• Rosenqvist, Marija Plahter; Meakins, Max William John; Planke, Sverre; Millett, John M.; Kjøll, Hans Jørgen & Voigt, Martin J. [Vis alle 7 forfattere av denne artikkelen] (2023). Reservoir properties and reactivity of the Faroe Islands Basalt Group: Investigating the potential for CO<inf>2</inf> storage in the North Atlantic Igneous Province. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 123. doi: 10.1016/j.ijggc.2023.103838. Fulltekst i vitenarkiv Vis sammendrag

  Offshore injection of CO2 into volcanic sequences of the North Atlantic Igneous Province may present a large-scale, permanent storage option through carbonate mineralization. To investigate this potential, onshore studies of reservoir properties and reactivity of the subaerially erupted Faroe Islands Basalt Group have been conducted. Outcrop and borehole samples reveal that the lava flow crusts commonly contain vesicles that have been filled with secondary minerals due to hydrothermal fluid circulation, however, unmineralized and highly porous layers do occur. Bulk density measurements, micro-computed tomography (µ-CT) image analysis, and microscope studies of samples from onshore boreholes give present-day porosities ranging from 0.5% to 36.2% in the volcanic sequences. The unmineralized brecciated lava flow crusts contain the largest estimated porosity and simulated absolute permeability (reaching up to 10−12 m2). µ-CT studies of the mineralized, brecciated flow crusts indicate initial porosities reaching up to 45%, before clogging. Kinetic experiments of rock dissolution show that the reactivity of the basalt and volcaniclastic sediments depends on the alteration state with more altered basalt being less reactive. However, the presence of reactive, high porosity, and high permeability flow crusts prior to clogging indicate the existence of promising and very large CO2 reservoirs in less altered offshore sequences.

• Ribas, I.; Reiners, A.; Zechmeister, M.; Caballero, J.A.; Morales, J.C. & Sabotta, S. [Vis alle 105 forfattere av denne artikkelen] (2023). The CARMENES search for exoplanets around M dwarfs: Guaranteed time observations Data Release 1 (2016-2020). Astronomy and Astrophysics (A & A). ISSN 0004-6361. 670. doi: 10.1051/0004-6361/202244879. Fulltekst i vitenarkiv Vis sammendrag

  Context. The CARMENES instrument, installed at the 3.5 m telescope of the Calar Alto Observatory in Almería, Spain, was conceived to deliver high-accuracy radial velocity (RV) measurements with long-term stability to search for temperate rocky planets around a sample of nearby cool stars. Moreover, the broad wavelength coverage was designed to provide a range of stellar activity indicators to assess the nature of potential RV signals and to provide valuable spectral information to help characterise the stellar targets. Aims. We describe the CARMENES guaranteed time observations (GTO), spanning from 2016 to 2020, during which 19 633 spectra for a sample of 362 targets were collected. We present the CARMENES Data Release 1 (DR1), which makes public all observations obtained during the GTO of the CARMENES survey. Methods. The CARMENES survey target selection was aimed at minimising biases, and about 70% of all known M dwarfs within 10 pc and accessible from Calar Alto were included. The data were pipeline-processed, and high-level data products, including 18 642 precise RVs for 345 targets, were derived. Time series data of spectroscopic activity indicators were also obtained. Results. We discuss the characteristics of the CARMENES data, the statistical properties of the stellar sample, and the spectroscopic measurements. We show examples of the use of CARMENES data and provide a contextual view of the exoplanet population revealed by the survey, including 33 new planets, 17 re-analysed planets, and 26 confirmed planets from transiting candidate follow-up. A subsample of 238 targets was used to derive updated planet occurrence rates, yielding an overall average of 1.44 ± 0.20 planets with 1 M⊕ < Mpl sin i < 1000 M⊕ and 1 day < Porb < 1000 days per star, and indicating that nearly every M dwarf hosts at least one planet. All the DR1 raw data, pipeline-processed data, and high-level data products are publicly available online. Conclusions. CARMENES data have proven very useful for identifying and measuring planetary companions. They are also suitable for a variety of additional applications, such as the determination of stellar fundamental and atmospheric properties, the characterisation of stellar activity, and the study of exoplanet atmospheres.

• Osmundsen, Per Terje; Svendby, Anne Kathrine; Braathen, Alvar; Bakke, Beate & Andersen, Torgeir Bjørge (2023). Fault growth and orthogonal shortening in transtensional supradetachment basins: Insights from the `Old Red´ of western Norway. Basin Research. ISSN 0950-091X. 35(4), s. 1407–1432. doi: 10.1111/bre.12759. Fulltekst i vitenarkiv Vis sammendrag

  For basins that evolve adjacent to large-magnitude normal faults, tectonic controls on sedimentation involve isostatic back rotation of an exhuming footwall and, commonly, the evolution of kilometre-scale extension-parallel folds. Based on observations from classic localities in western Norway, we propose a three-stage evolution scenario for transtensional supradetachment basins where the basins become progressively re-arranged because of core complex exhumation and subsequent orthogonal shortening. Extension-parallel transverse synclines initially form due to a normal displacement gradient, but when displacements accumulate beyond a certain magnitude, the hanging wall increasingly responds to core complex exhumation and the original depocentre, formed close to the original area of maximum displacement, will become inverted and dismembered above the core complex. Two new synclinal depocentres will develop along the flanks. Because these synclines form by extensional fault growth rather than by shortening, they will be associated with widening of the basin and onlap onto basement at high angles to the maximum elongation trend with overall grain-size decrease and retrogradational stacking patterns. Further, because these synclines grow away from the evolving core complex, sedimentary units will become asymmetrically distributed inside each syncline in such a way that the oldest deposits in the syncline will be preserved on the flank most proximal to the core complex. In transtensional environments, a third evolutionary stage may involve constrictional strain where extension-parallel folds and reverse faults produced by orthogonal shortening enhance or interact with other structures. Ultimately, initial extensional sub-basins may become warped across extension-parallel folds. Hanging wall deformation will be manifested in shifting accommodation patterns, with depocentres that generally migrate in the direction of the detachment fault. Accommodation patterns initially related to megafault growth may conceptually evolve into depocentres controlled by orthogonal shortening.

• Turino, V.; Magni, Valentina; Kjøll, Hans Jørgen & Jakob, Johannes (2023). The Effect of Magma Poor and Magma Rich Rifted Margins on Continental Collision Dynamics. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 128(12). doi: 10.1029/2023JB027173. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The transition between non‐rifted continental lithosphere and oceanic lithosphere in rifted margins can display a wide range of characteristics, depending on the regional tectonic evolution. The velocity and duration of the rifting process as well as the geodynamic setting influence the properties and geometry of the margins, which are often grouped into two main categories: magma‐poor and magma‐rich. We show how different types of rifted margins can influence the dynamics of continental collision, focusing on the time and depth of slab break‐off after collision and the fate of margin material. We find that rifted margins have a noticeable impact on subduction dynamics, as we observe large variability in slab break‐off times and depths. In particular, the presence of a rifted margin can delay slab break‐off to up to 60 Myr after the onset of collision. Our results show that a large portion of the weak crust of magma‐poor margins is likely to detach from the subducting plate and accrete to the upper plate, while the dense and strong mafic and ultramafic component of magma‐rich margins causes most of the margin to subduct and be lost into the mantle, leaving only a small fraction of transitional and oceanic crust at the surface. Therefore, the volume of accreted material is much larger when the margin is magma‐poor than magma‐rich, which is consistent with geological observations that fossil magma‐poor rifted margins are preserved in many mountain ranges, whereas remnants of magma‐rich rifted margins are scarce.

• Das, Pratik Kumar; Mondal, Sudip Kumar; Mandal, Nibir & Arya, A. (2023). p-T-dependent structural transformations of Zn-monochalcogenides to switch their semiconductor–metal transition: a DFT study. Applied Physics A: Materials Science & Processing. ISSN 0947-8396. 129. doi: 10.1007/s00339-023-06777-w. Fulltekst i vitenarkiv
• Geng, Ming & Mohn, Chris Erik (2023). Influence of electronic entropy on Hellmann-Feynman forces in ab initio molecular dynamics with large temperature changes. Physical review B (PRB). ISSN 2469-9950. 108(13). doi: 10.1103/PhysRevB.108.134110. Fulltekst i vitenarkiv
• Schultz, Bo Pagh; Huggett, Jennifer M.; Kennedy, George L.; Burger, Paul; Friis, Henrik & Jensen, Anne M. [Vis alle 10 forfattere av denne artikkelen] (2023). Petrography and geochemical analysis of Arctic ikaite pseudomorphs from Utqiaġvik (Barrow), Alaska. Norwegian Journal of Geology. ISSN 2387-5844. 103(1), s. 1–17. doi: 10.17850/njg103-1-3. Fulltekst i vitenarkiv Vis sammendrag

  Ikaite and pseudomorphs thereafter (“glendonites”) are a potentially powerful tool for palaeoclimatic studies, as a low-temperature proxy. However, much uncertainty still surrounds the drivers of ikaite formation, in particular prerequisite thermal and chemical conditions. Furthermore, the ikaite to glendonite transformation is not fully understood, and it was unclear which calcite phases in glendonites were ikaite-derived and which were later diagenetic calcites. This leads to difficulties in choosing which phase to analyse in order to reconstruct the original ikaite growth environmental conditions. Petrographic examination of air-transformed ikaite from the Isatkoak Lagoon in Utqia?vik, Alaska, confirms that both ’Type I’ and ’Type II’ calcite phases seen in glendonites are directly derived from ikaite breakdown and not from secondary sources. Clumped isotope temperature reconstructions for transformed ikaites from Utqia?vik, and comparison to Recent glendonites from the White Sea, Russia, confirm that clumped isotope thermometry may be used to reconstruct ikaite growth temperatures, whilst stable isotopes and minor elemental analysis reveal that a range of geochemical conditions characterise ikaite growth sites.

• Swadba, K. E.; Davis, Anne Hope; Zurkowski, C. C.; Chariton, S.; Prakapenka, V. B. & Campbell, A. J. (2023). Disproportionation of Iron in Almandine-Pyrope-Grossular Garnet From 25 to 65 GPa. Geochemistry Geophysics Geosystems. 24(10). doi: 10.1029/2023GC011081. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The production of metal via the iron disproportionation reaction in the deep Earth has been a long debated topic with important implications for the geochemistry of the lower mantle. To explore the occurrence of the iron disproportionation reaction from 25 to 65 GPa, a natural almandine‐pyrope‐grossular garnet was studied with in situ X‐ray diffraction (XRD) in the laser‐heated diamond anvil cell and ex situ scanning electron microscopy (SEM) techniques. Upon heating the natural almandine‐pyrope‐grossular garnet up to 3000 K up to 65 GPa, the formation of phase assemblage consisting of bridgmanite, stishovite, and davemaoite was confirmed by XRD, but because of the low abundance of Fe metal and small grain size, XRD was determined not to be effective in detecting the disproportionation reaction. Examination of the samples recovered between 39 and 64 GPa by SEM analysis revealed the presence of nm‐scale disproportionated iron metal grains as an additional product of this reaction that was not detectable in the XRD patterns. Volume compression data of bridgmanite synthesized in the experiments were fit to the Birch‐Murnaghan equation of state and compared to similar compositions. Bridgmanite was found to decompress to the LiNbO 3 ‐type structure, indicating a high FeAlO 3 content, in accordance with the occurrence of a disproportionation reaction. The experimental confirmation of disproportionated metallic Fe has significant implications for the distribution of siderophile and volatile elements in the lower mantle.

• Seton, Maria; Williams, Simon E.; Domeier, Mathew Michael; Collins, Alan S. & Sigloch, Karin (2023). Deconstructing plate tectonic reconstructions. Nature Reviews Earth & Environment. 4, s. 185–204. doi: 10.1038/s43017-022-00384-8. Fulltekst i vitenarkiv
• Kossakowski, D.; Kürster, M.; Trifonov, T.; Henning, Th.; Kemmer, J. & Caballero, J.A. [Vis alle 50 forfattere av denne artikkelen] (2023). The CARMENES search for exoplanets around M dwarfs: Wolf 1069 b: Earth-mass planet in the habitable zone of a nearby, very low-mass star. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 670. doi: 10.1051/0004-6361/202245322. Fulltekst i vitenarkiv Vis sammendrag

  We present the discovery of an Earth-mass planet (Mb sin i = 1.26 ± 0.21 M⊕) on a 15.6 d orbit of a relatively nearby (d ~ 9.6 pc) and low-mass (0.167 ± 0.011 M⊙) M5.0 V star, Wolf 1069. Sitting at a separation of 0.0672 ± 0.0014 au away from the host star puts Wolf 1069 b in the habitable zone (HZ), receiving an incident flux of S = 0.652 ± 0.029 S⊕. The planetary signal was detected using telluric-corrected radial-velocity (RV) data from the CARMENES spectrograph, amounting to a total of 262 spectroscopic observations covering almost four years. There are additional long-period signals in the RVs, one of which we attribute to the stellar rotation period. This is possible thanks to our photometric analysis including new, well-sampled monitoring campaigns undergone with the OSN and TJO facilities that supplement archival photometry (i.e., from MEarth and SuperWASP), and this yielded an updated rotational period range of Prot = 150–170 d, with a likely value at 169.3−3.6+3.7. The stellar activity indicators provided by the CARMENES spectra likewise demonstrate evidence for the slow rotation period, though not as accurately due to possible factors such as signal aliasing or spot evolution. Our detectability limits indicate that additional planets more massive than one Earth mass with orbital periods of less than 10 days can be ruled out, suggesting that perhaps Wolf 1069 b had a violent formation history. This planet is also the sixth closest Earth-mass planet situated in the conservative HZ, after Proxima Centauri b, GJ 1061 d, Teegarden’s Star c, and GJ 1002 b and c. Despite not transiting, Wolf 1069 b is nonetheless a very promising target for future three-dimensional climate models to investigate various habitability cases as well as for sub-m s−1 RV campaigns to search for potential inner sub-Earth-mass planets in order to test planet formation theories.

• Vaes, Bram; Hinsbergen, Douwe Van; Lagemaat, Suzanna H.A. van de; Wiel, Erik van der; Lom, Nalan & Advokaat, Eldert L. [Vis alle 15 forfattere av denne artikkelen] (2023). A global apparent polar wander path for the last 320 Ma calculated from site-level paleomagnetic data. Earth-Science Reviews. ISSN 0012-8252. 245. doi: 10.1016/j.earscirev.2023.104547. Fulltekst i vitenarkiv Vis sammendrag

  Apparent polar wander paths (APWPs) calculated from paleomagnetic data describe the motion of tectonic plates relative to the Earth's rotation axis through geological time, providing a quantitative paleogeographic framework for studying the evolution of Earth's interior, surface, and atmosphere. Previous APWPs were typically calculated from collections of paleomagnetic poles, with each pole computed from collections of paleomagnetic sites, and each site representing a spot reading of the paleomagnetic field. It was recently shown that the choice of how sites are distributed over poles strongly determines the confidence region around APWPs and possibly the APWP itself, and that the number of paleomagnetic data used to compute a single paleomagnetic pole varies widely and is essentially arbitrary. Here, we use a recently proposed method to overcome this problem and provide a new global APWP for the last 320 million years that is calculated from simulated site-level paleomagnetic data instead of from paleopoles, in which spatial and temporal uncertainties of the original datasets are incorporated. We provide an updated global paleomagnetic database scrutinized against quantitative, stringent quality criteria, and use an updated global plate motion model. The new global APWP follows the same trend as the most recent pole-based APWP but has smaller uncertainties. This demonstrates that the first-order geometry of the global APWP is robust and reproducible. Moreover, we find that previously identified peaks in APW rate disappear when calculating the APWP from site-level data and correcting for a temporal bias in the underlying data. Finally, we show that a higher-resolution global APWP frame may be determined for time intervals with high data density, but that this is not yet feasible for the entire 320–0 Ma time span. Calculating polar wander from site-level data provides opportunities to significantly improve the quality and resolution of the global APWP by collecting large and well-dated paleomagnetic datasets from stable plate interiors, which may contribute to solving detailed Earth scientific problems that rely on a paleomagnetic reference frame.

• Hatalova, Petra; Brasser, R.; Mamonova, Elena & Werner, Stephanie C. (2023). Forming rocky exoplanets around K-dwarf stars. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 676. doi: 10.1051/0004-6361/202346332. Fulltekst i vitenarkiv Vis sammendrag

  Context. New space telescopes, such as the upcoming PLATO mission, aim to detect and study thousands of exoplanets, especially terrestrial planets around main-sequence stars. This motivates us to study how these planets formed. How multiple close-in super-Earths form around stars with masses lower than that of the Sun is still an open issue. Several recent modeling studies have focused on planet formation around M-dwarf stars, but so far no studies have focused specifically on K dwarfs, which are of particular interest in the search for extraterrestrial life. Aims. We aim to reproduce the currently known population of close-in super-Earths observed around K-dwarf stars and their system characteristics. Additionally, we investigate whether the planetary systems that we form allow us to decide which initial conditions are the most favorable. Methods. We performed 48 high-resolution N -body simulations of planet formation via planetesimal accretion using the existing GENGA software running on GPUs. In the simulations we varied the initial protoplanetary disk mass and the solid and gas surface density profiles. Each simulation began with 12 000 bodies with radii of between 200 and 2000 km around two different stars, with masses of 0.6 and 0.8 M ⊙ . Most simulations ran for 20 Myr, with several simulations extended to 40 or 100 Myr. Results. The mass distributions for the planets with masses between 2 and 12 M ⊕ show a strong preference for planets with masses M p &lt; 6 M ⊕ and a lesser preference for planets with larger masses, whereas the mass distribution for the observed sample increases almost linearly. However, we managed to reproduce the main characteristics and architectures of the known planetary systems and produce mostly long-term angular-momentum-deficit-stable, nonresonant systems, but we require an initial disk mass of 15 M ⊕ or higher and a gas surface density value at 1 AU of 1500 g cm −2 or higher. Our simulations also produce many low-mass planets with M &lt; 2 M ⊕ , which are not yet found in the observed population, probably due to the observational biases. Earth-mass planets form quickly (usually within a few million years), mostly before the gas disk dispersal. The final systems contain only a small number of planets with masses M p &gt; 10 M ⊕ , which could possibly accrete substantial amounts of gas, and these formed after the gas had mostly dissipated. Conclusions. We mostly manage to reproduce observed K-dwarf exoplanetary systems from our GPU simulations.

• Ramirez, Florence Dela Cruz; Conrad, Clinton Phillips & Selway, Katherine (2023). Grain size reduction by plug flow in the wet oceanic upper mantle explains the asthenosphere's low seismic Q zone. Earth and Planetary Science Letters. ISSN 0012-821X. 616. doi: 10.1016/j.epsl.2023.118232. Fulltekst i vitenarkiv Vis sammendrag

  The prominent seismic low-velocity zone (LVZ) in the oceanic low-viscosity asthenosphere is approximately coincident with the low seismic Q zone (LQZ; a zone of high seismic attenuation). Small olivine grain sizes could link these seismic and rheological properties because they reduce viscosity, seismic velocity and seismic Q. Because rock deformation reduces grain sizes, the asthenosphere's seismic properties can place constraints on asthenospheric flow. To determine dominant flow patterns, we develop a self-consistent analytical 1-D channel flow model that accounts for upper mantle rheology and its dependence on flow-modified grain-sizes, water content, and melt fraction, for flow driven by both surface plate motions (Couette flow) and/or horizontal pressure gradients (Poiseuille flow). We find that Couette flow dominates if the upper mantle is dry, and plug flow (a Poiseuille flow for power law rheology) dominates if it is weakened by wet conditions. A plug flow configuration spanning the upper 670 km of the mantle best explains the LQZ in the asthenosphere, and can be attributed to significant grain-size reduction due to extensive shearing across the asthenosphere. This flow configuration also explains high seismic Q values below the asthenosphere associated with minimal shear deformation and large grain sizes above the mantle transition zone. We suggest that the asthenospheric LQZ and LVZ seismic anomalies can be largely explained by grain-size variations associated with plug flow in the wet upper mantle.

• Haddad, Antoine; Chiarabba, C.; Lazar, M.; Mazzini, Adriano; Polonia, Alina & Gasperini, Luca [Vis alle 7 forfattere av denne artikkelen] (2023). Rifting-Driven Magmatism Along the Dead Sea Continental Transform Fault. Geophysical Research Letters. ISSN 0094-8276. 50(4). doi: 10.1029/2022GL099964. Fulltekst i vitenarkiv Vis sammendrag

  The Dead Sea Fault (DSF) is a crustal-scale continental transform fault separating the African and the Arabian plates. Neogene to Quaternary volcanic activity is well-spread in Northern Israel. Yet, the origin of the magmas that fed the eruptions is still unpinned. Our local earthquake tomography depicts velocity distributions typical of rifting settings. At 9 km depth, a prominent high Vp/Vs anomaly marks the presence of cooling melts. We propose that protracted transtension along the DSF caused crustal thinning promoting the emplacement of magmatic bodies. Crustal emplacements of magmas in Northern Israel reconcile multiple observations, including the high geothermal gradient, the prominent magnetic anomalies and the traces of mantle-derived fluids in the springs across the Sea of Galilee. We provide a compelling evidence for rifting in segments of the DSF and identify the potential source of magmatism that fed part of the volcanic activity of the area.

• Hyung, Eugenia; Sedaghatpour, Fatemeh; Larsen, Bjørn Tore; Neumann, Else Ragnhild; Eriksen, Zachary T. & Petaev, Michail I. [Vis alle 7 forfattere av denne artikkelen] (2023). A peridotite source for strongly alkalic ultrabasic HIMU lavas of the Oslo Rift, Norway. Chemical Geology. ISSN 0009-2541. 622. doi: 10.1016/j.chemgeo.2023.121377. Fulltekst i vitenarkiv
• Baker, Don R.; Callegaro, Sara; Marzoli, Andrea; Min, Angelo De; Geraki, Kalotina & Whitehouse, Martin, J. [Vis alle 8 forfattere av denne artikkelen] (2023). Sulfur and chlorine in nakhlite clinopyroxenes: Source region concentrations and magmatic evolution. Geochimica et Cosmochimica Acta. ISSN 0016-7037. 359, s. 1–19. doi: 10.1016/j.gca.2023.08.007. Fulltekst i vitenarkiv Vis sammendrag

  The volatile concentrations of the martian mantle and martian magmas remain important questions due to their role in petrogenesis and planetary habitability. The sulfur and chlorine concentrations, and their spatial distribution, in clinopyroxenes from nakhlites MIL 03346, Nakhla, and NWA 998 were measured to provide insight into these volatiles in the parental melts and source regions of nakhlites, and to constrain the evolution of the nakhlite melts. Sulfur and chlorine in four clinopyroxene crystals from MIL 03346, four from Nakhla, and five from NWA 998 were measured in crystal cores and rims by synchrotron X-ray fluorescence using beamline I18 at the Diamond Light Source. Portions of two crystals from MIL 03346 and one from Nakhla were mapped for S and Cl; a few reconnaissance analyses of Cl and F in MIL 03346 and Nakhla were made by ion microprobe. Clinopyroxene cores in Nakhla and NWA 998 contain ∼ 10 ppm S, ∼ 10 ppm Cl and ∼ 74 ppm F (only Nakhla analyzed), whereas the cores of MIL 03346 contain ∼ 10 ppm S, ∼ 5 ppm Cl and ∼ 53 ppm F. Using the volatile concentrations in the cores combined with previously determined partition coefficients we calculate that these clinopyroxenes crystallized from evolved basaltic melts containing ∼ 500 ppm S, ∼ 500 to 1900 ppm Cl, and 160 to 420 ppm F. These evolved melts can be used to calculate primitive melts in equilibrium with martian peridotite and the concentrations of S, Cl and F in the mantle source region of the nakhlite melts. Depending upon the extent of melting (5 to 30 %) necessary to produce the primary melts associated with nakhlites, our calculations indicate that the nakhlite source region has a S concentration between 20 (5 % melting) to 120 ppm (30 % melting), Cl between 16 to 97 ppm, and F between 14 to 48 ppm. These concentrations in the nakhlite magma source region are similar to previous estimates for the martian mantle; our calculated source region concentrations of F and Cl agree best with previous estimates if the martian mantle undergoes 10 to 20% melting to produce primary magmas that evolve to be parental to nakhlites. However, our maximum estimated sulfur concentration of the source (calculated for 30 % melting) is near previous minimum estimates for the martian mantle, suggesting the possibility that the nakhlite source region is depleted in sulfur relative to much of Mars’ mantle. Mapping the spatial distribution of volatiles in three clinopyroxene crystals demonstrates that S and Cl concentrations of the evolving melts changed significantly from the core to the rim, particularly those in MIL 03346. Increasing S and Cl concentrations between the core and rim of MIL 03346 crystals are attributed to incorporation of additional volatiles through assimilation, but the Nakhla crystal shows no such evidence. However, concentrations of Cl and S at some outer crystal rims of one MIL 03346 crystal decrease, most probably due to volatile degassing during the final stages of clinopyroxene growth.

• Tymiński, Zbigniew; Hult, Mikael; Krzesinska, Agata Magdalena; Tymińska, Katarzyna; Lutter, Guillaume & Saganowski, Paweł [Vis alle 12 forfattere av denne artikkelen] (2023). Underground radioactivity measurements of meteorites: Development of methods suitable to determine precise terrestrial age of recent falls. Applied Radiation and Isotopes. ISSN 0969-8043. 195. doi: 10.1016/j.apradiso.2023.110733. Fulltekst i vitenarkiv
• Mazzini, Adriano; Sciarra, A.; Lupi, M.; Ascough, P; Akhmanov, G & Karyono, Karyono [Vis alle 7 forfattere av denne artikkelen] (2023). Deep fluids migration and submarine emersion of the Kalang Anyar mud volcano (Java, Indonesia): A multidisciplinary study. Marine and Petroleum Geology. ISSN 0264-8172. 148. doi: 10.1016/j.marpetgeo.2022.105970. Fulltekst i vitenarkiv Vis sammendrag

  North-east Java is part of a large sedimentary basin containing hydrocarbon provinces that feature diffuse hydrothermal systems, mud volcanoes, and degassing sites. Seismic profiles acquired to explore the basin reveal a broad distribution of palaeo- and modern piercement structures. The Watukosek fault system links the volcanic arc, to the south, with the Sidoarjo province, to the north. Several piercement structures, including the Kalang Anyar mud volcano, are hosted along this left-lateral strike-slip system that favors the migration of crustal fluids in this part of the basin. Here, we present a multidisciplinary geological, geophysical and geochemical study conducted at Kalang Anyar where dozens of seepage sites are active in the crater area and intermittently emit bursts oil, gas, mud, and water. The emitted gasses are methane-dominated with smaller amounts of heavier hydrocarbons and CO2. Unlike most mud volcanoes, at Kalang Anyar the mixed-thermogenic origin of the methane is coupled with geothermal anomalies, as indicated by helium and CO2 isotopic values (δ13CCO2 as high as −4‰) that suggest the input of mantle-derived gas. Our gas flux measurements reveal that Kalang Anyar emits about 1.62 and 5.75 t yr−1 of CO2 and CH4, respectively. The intense bubbling gives rise to a typical drumbeat seismic signal characterized by dominant frequencies around of 3–4 Hz (and up to 15 Hz). We interpret the drumbeat as fluids rising and resonating through shallow plumbing system of Kalang Anyar. Erupted clasts with different lithologies and shells are scattered across the mud volcano area, while the edges of the crater zone include cubic meter-sized carbonate-cemented blocks and ridges that contain siliciclastic sediments and abundant chemosymbiotic bivalves. Carbon isotope analyses of the carbonate cement (δ13C as low as −48.8‰) identify the latter as methanogenic chemoherms. Radiocarbon (14C) dating of bivalves cemented in the blocks indicates an age of 1890-1488 BP. These results indicate that the activity of Kalang Anyar MV dates from when the area was below sea level and that the microbially-mediated precipitation of carbonates was ongoing during subaqueous methane seepage at the crater site. To the best of our knowledge, Kalang Anyar is the first example of a mud volcano that progressed from subaqueous to subaerial conditions during marine regression, displaying evidence of former marine activity (i.e. methanogenic carbonates) and current subaerial degassing at numerous seepage sites. Potentially eruptive phases represent a clear geohazard for the numerous settlements constructed inside the mud volcano. In light of this, it may be prudent to apply stricter rules for development activities, such as housing construction permits that consider the possibility of potentially catastrophic events, and apply steps to mitigate these hazards.

• Hesselbo, Stephen P.; Al-Suwaidi, Aisha; Baker, Sarah J.; Ballabio, Giorgia; Belcher, Claire M. & Bond, Andrew [Vis alle 73 forfattere av denne artikkelen] (2023). Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): Towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic. Scientific Drilling. ISSN 1816-8957. 32, s. 1–25. doi: 10.5194/sd-32-1-2023. Fulltekst i vitenarkiv Vis sammendrag

  Abstract. Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.

• Cala, Juan Camilo Meza; Tsikalas, Filippos; Abdelmalak, Mohamed Mansour & Faleide, Jan Inge (2023). Structural analysis and measured extension in fault complexes along the Lofoten-Vesterålen margin, offshore Norway, in the context of crustal-scale rifting towards breakup in NE Atlantic. Basin Research. ISSN 0950-091X. 35(4), s. 1329–1361. doi: 10.1111/bre.12756. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Late Cretaceous–Palaeocene continental extension within the Lofoten‐Vesterålen margin is investigated by integrating 2D‐3D seismic and potential field datasets, together with updated crustal transects. Most of that deformation is recorded by two low‐angle detachment structures named West Røst High Fault Complex (WRHFC) and North Utrøst Ridge Fault Complex (NURFC) located at the southern and central‐northern portions of the studied area, respectively. Multiple extensional episodes of various intensities were mapped as different fault stages, including one Albian‐Cenomanian phase, four early Late Cretaceous phases, three Late Cretaceous to latest Cretaceous–Palaeocene phases, and one Palaeocene phase. The WRHFC is narrower in extent and has accommodated a relatively greater amount of localized extension (ca. 18–19 km), whereas the NURFC occupies a wider area with widespread extension intensity (ca. 6–8 km). In comparison, the total across‐margin average extension within the southern, central, and northern portions of the Lofoten‐Vesterålen and NE Greenland conjugate margins are ca. 192, 221, and 266 km, respectively. Such results indicate an apparent extension discrepancy between derived extension from measured fault‐block geometries within the fault complexes and the whole conjugate margin system, with only ca. 11% and 13% of the extension seen on the studied seismic profiles on the WRHFC and NURFC, respectively. The corrected maximum extension for purely sub‐seismic resolution faulting on both the WRHFC and NURFC fault complexes is ca. 164 and 46 km, respectively. Finally, both WRHFC and NURFC structures provide key evidence for a ductile mode of deformation towards breakup that is expressed through shear zones‐rift topography interactions with overlaying listric/detachment faults. These features reflect the resulting multiphase tectonic evolution across the asymmetric Lofoten‐Vesterålen and NE Greenland conjugate margins, and the obliquity in the breakup axis location along them. The study outcomes are pertinent and applicable to understand the breakup evolution of the northern NE Atlantic and its vicinity.

• Dowding, Elizabeth May; Akulov, Nikolay Ivanovich & Mashchuk, Irina Mikhailovna (2023). Survivorship dynamics of the flora of Devonian Angarida. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 290(1990). doi: 10.1098/rspb.2022.1079. Fulltekst i vitenarkiv
• Gallo, Leandro Cesar; Domeier, Mathew Michael; Sapienza, F.; Swanson-Hysell, N. L.; Vaes, B. & Zhang, Y. [Vis alle 14 forfattere av denne artikkelen] (2023). Embracing Uncertainty to Resolve Polar Wander: A Case Study of Cenozoic North America. Geophysical Research Letters. ISSN 0094-8276. 50(11). doi: 10.1029/2023GL103436. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Our understanding of Earth's paleogeography relies heavily on paleomagnetic apparent polar wander paths (APWPs), which represent the time‐dependent position of Earth's spin axis relative to a given block of lithosphere. However, conventional approaches to APWP construction have significant limitations. First, the paleomagnetic record contains substantial noise that is not integrated into APWPs. Second, parametric assumptions are adopted to represent spatial and temporal uncertainties even where the underlying data do not conform to the assumed distributions. The consequences of these limitations remain largely unknown. Here, we address these challenges with a bottom‐up Monte Carlo uncertainty propagation scheme that operates on site‐level paleomagnetic data. To demonstrate our methodology, we present an extensive compilation of site‐level Cenozoic paleomagnetic data from North America, which we use to generate a high‐resolution APWP. Our results demonstrate that even in the presence of substantial noise, polar wandering can be assessed with unprecedented temporal and spatial resolution.

• Paul, Jyotirmoy; Conrad, Clinton Phillips; Becker, Thorsten W. & Ghosh, Attreyee (2023). Convective Self-Compression of Cratons and the Stabilization of Old Lithosphere. Geophysical Research Letters. ISSN 0094-8276. 50(4). doi: 10.1029/2022GL101842. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Despite being exposed to convective stresses for much of the Earth's history, cratonic roots appear capable of resisting mantle shearing. This tectonic stability can be attributed to the neutral density and higher strength of cratons. However, the excess thickness of cratons and their higher viscosity amplify coupling to underlying mantle flow, which could be destabilizing. To investigate the stresses that a convecting mantle exerts on cratons that are both strong and thick, we developed instantaneous global spherical numerical models that incorporate present‐day geoemetry of cratons within active mantle flow. Our results show that mantle flow is diverted downward beneath thick and viscous cratonic roots, giving rise to a ring of elevated and inwardly‐convergent tractions along a craton's periphery. These tractions induce regional compressive stress regimes within cratonic interiors. Such compression could serve to stabilize older continental lithosphere against mantle shearing, thus adding an additional factor that promotes cratonic longevity.

• Robert, Boris; Corfu, Fernando; Domeier, Mathew Michael & Blein, Olivier (2023). Evidence for large disturbances of the Ediacaran geomagnetic field from West Africa. Precambrian Research. ISSN 0301-9268. 394. doi: 10.1016/j.precamres.2023.107095. Fulltekst i vitenarkiv Vis sammendrag

  Constraining the paleogeography of the Ediacaran is crucial for understanding the extensive tectonic, biological and geochemical changes that occurred during that epoch. Paleomagnetism is an essential tool for reconstructing the Ediacaran paleogeography but it is complicated because the paleomagnetic data of that age display unusually fast and large directional oscillations. Two main competing hypotheses have been proposed: the occurrence of very fast True Polar Wander (TPW) episodes, which correspond to the motion of the planetary spin axis relative to the solid Earth, or strong geomagnetic field disturbances that could potentially be dominated by an equatorial dipole field. Their implications for paleogeographic reconstructions are radically different as TPW would result in a major latitudinal shift of continents of up to ∼ 90°. In this study, we focus on one rapid paleomagnetic change recorded in pyroclastic rocks of the Ouarzazate Group in the Anti-Atlas Belt (Morocco) that has been interpreted to reflect an exceptionally fast episode of True Polar Wander between ∼ 575 and 565 Ma. To further test this hypothesis, tight constraints on the rate of the paleomagnetic directional change are needed, as TPW is speed-limited by mantle viscosity. Here, we present high-resolution Chemical Abrasion Isotope-Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS) U-Pb dates on zircons from seven pyroclastic levels distributed stratigraphically below, in between and above the horizons where the large paleomagnetic change is observed. Based on these new data, we estimate the associated lower bound rate of the apparent polar motion related to this abrupt paleomagnetic change to be 11.6°/Myrs [5.5 – 17.9]. This value is much higher than the TPW speed limit estimated from numerical simulations, suggesting that this large paleomagnetic change cannot be explained by TPW. It could rather be associated with intense perturbations of the Ediacaran geomagnetic field potentially oscillating from an axial to an equatorial dipole. The paleomagnetic pole that we interpret as referring to the axial dipole field would imply that West Africa was located at high latitude during the mid-Ediacaran.

• Pereira, Pereira Francisco; Silva, Ícaro Dias da; Rodríguez, Cármen; Corfu, Fernando & Castro, António (2023). Visean high-K mafic–intermediate plutonic rocks of the Ossa–Morena Zone (SW Iberia): implications for regional extensional tectonics. Geological Society Special Publication. ISSN 0305-8719. 531, s. 345–367. doi: 10.1144/SP531-2022-118. Fulltekst i vitenarkiv
• Kabanov, Pavel; Gouwy, Sofie; Boon, Annique van der & Grasby, Stephen (2023). Nature of Devonian anoxic events based on multiproxy records from Panthalassa, NW Canada. Global and Planetary Change. ISSN 0921-8181. 227. doi: 10.1016/j.gloplacha.2023.104176. Fulltekst i vitenarkiv
• Herrick, Robert R.; Bjonnes, Evan T.; Carter, Lynn M.; Gerya, Taras; Ghail, Richard C. & Gillmann, Cédric [Vis alle 15 forfattere av denne artikkelen] (2023). Resurfacing History and Volcanic Activity of Venus. Space Science Reviews. ISSN 0038-6308. 219. doi: 10.1007/s11214-023-00966-y. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Photogeologic principles can be used to suggest possible sequences of events that result in the present planetary surface. The most common method of evaluating the absolute age of a planetary surface remotely is to count the number of impact craters that have occurred after the surface formed, with the assumption that the craters occur in a spatially random fashion over time. Using additional assumptions, craters that have been partially modified by later geologic activity can be used to assess the time frames for an interpreted sequence of events. The total number of craters on Venus is low and the spatial distribution taken by itself is nearly indistinguishable from random. The overall implication is that the Venusian surface is much closer to Earth in its youthfulness than the other, smaller inner solar system bodies. There are differing interpretations of the extent to which volcanism and tectonics have modified the craters and of the regional and global sequences of geologic events. Consequently, a spectrum of global resurfacing views has emerged. These range from a planet that has evolved to have limited current volcanism and tectonics concentrated in a few zones to a planet with Earth-like levels of activity occurring everywhere at similar rates but in different ways. Analyses of the geologic record have provided observations that are challenging to reconcile with either of the endmember views. The interpretation of a global evolution with time in the nature of geologic activity relies on assumptions that have been challenged, but there are other observations of areally extensive short-lived features such as canali that are challenging to reconcile with a view of different regions evolving independently. Future data, especially high-resolution imaging and topography, can provide the details to resolve some of the issues. These different global-evolution viewpoints must tie to assessments of present-day volcanic and tectonic activity levels that can be made with the data from upcoming missions.

• Montelli, Aleksandr; Solovyeva, Marina; Akhmanov, Grigorii; Mazzini, Adriano; Piatilova, Anna & Bakay, Elena [Vis alle 7 forfattere av denne artikkelen] (2023). The geomorphic record of marine-based ice dome decay: Final collapse of the Barents Sea ice sheet. Quaternary Science Reviews. ISSN 0277-3791. 303. doi: 10.1016/j.quascirev.2023.107973. Fulltekst i vitenarkiv Vis sammendrag

  New high-resolution geophysical data acquired from eastern Storbanken in the central Barents Sea allow reconstruction of the flow of marine-based ice dome during the final stages of ice-sheet decay. Ice-marginal and subglacial landforms show diverging and quasi-radial grounding-line retreat patterns, implying that an isolated, dynamic, shrinking ice dome was centred at ∼77° N 40° E on eastern Storbanken prior to final marine-based ice-sheet collapse. This geomorphological reconstruction contrasts with previous numerical and observational models that infer a northward-migrating ice dome or crest that extended longitudinally from Svalbard to Franz-Josef Land prior to its eventual demise. Our results provide an important past analogue for late-stage decay of marine ice domes, as well as robust empirical constraints that can be used to calibrate numerical models simulating the behaviour of marine-based ice sheets in a warming environment.

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• Weerdesteijn, Maaike Francine Maria & Conrad, Clinton Phillips (2024). Rapid Earth uplift in Southeast Greenland driven by deglaciation above the Iceland Plume Track. Fulltekst i vitenarkiv
• Weerdesteijn, Maaike Francine Maria & Conrad, Clinton Phillips (2024). Rapid Earth uplift in southeast Greenland driven by recent ice melt above low-viscosity upper mantle. Fulltekst i vitenarkiv
• Conrad, Clinton Phillips; Weerdesteijn, Maaike Francine Maria; Ramirez, Florence Dela Cruz & Selway, Kate (2024). Rapid Earth uplift where the Iceland Plume Track Crosses Greenland: GIA modelling and MT Constraints. Fulltekst i vitenarkiv
• Trønnes, Reidar G; Grømer, Bendik; Mohn, Chris Erik; Hernandez, Jean-Alexis; Guren, MG & Baron, Marzena Anna (2024). May 24: Trønnes RG, Grømer B, Mohn CE, Hernandez JA, Guren MG, Baron MA. Dense residual davemaoite in the lowermost mantle excludes the core and lowermost mantle as sources of the "primordial" He and Ne isotopic signal. PHAB seminar. Fulltekst i vitenarkiv
• Marcilly, Chloe M.; Torsvik, Trond Helge & Conrad, Clinton Phillips (2024). Corrigendum to “Global Phanerozoic sea levels from paleogeographic flooding maps” [Gondwana Res. 110 (2022) 128–142, (S1342937X22001563), (10.1016/j.gr.2022.05.011)]. Gondwana Research. ISSN 1342-937X. 129, s. 367–368. doi: 10.1016/j.gr.2024.01.006. Fulltekst i vitenarkiv
• Jones, Morgan Thomas (2023). Tracing North Atlantic volcanism and seaway connectivity across the Paleocene–Eocene Thermal Maximum (PETM). Fulltekst i vitenarkiv
• Widemann, Thomas; Smrekar, Suzanne E.; Garvin, James B.; Straume-Lindner, Anne Grete; Ocampo, Adriana C. & Schulte, Mitchell D. [Vis alle 45 forfattere av denne artikkelen] (2023). Correction to: Venus Evolution Through Time: Key Science Questions, Selected Mission Concepts and Future Investigations (Space Science Reviews, (2023), 219, 7, (56), 10.1007/s11214-023-00992-w). Space Science Reviews. ISSN 0038-6308. 219(8). doi: 10.1007/s11214-023-01022-5. Fulltekst i vitenarkiv
• Andersen, Torgeir Bjørge (2023). Foredrag: Bergrunnsgeologien i Fjordkysten Regional og Geopark. Fulltekst i vitenarkiv
• Svensen, Henrik Hovland (2023). Du kan ofte se granitt og gneis når du går tur, men hvordan ble de til? [Internet]. forskning.no. Fulltekst i vitenarkiv
• Weerdesteijn, Maaike Francine Maria & Conrad, Clinton Phillips (2023). Rapid Earth uplift in southeast Greenland driven by recent ice melt above low-viscosity upper mantle. Fulltekst i vitenarkiv
• Austrheim, Håkon Olaf & Andersen, Torgeir Bjørge (2023). Extreme enrichment of Arsenic and Antimony in altered peridotite; mechanism and consequences. Fulltekst i vitenarkiv
• Durn, Goran; Perković, Ivor; Razum, Ivan; Ottner, Franz; Škapin, Srečo D. & Faivre, Sanja [Vis alle 9 forfattere av denne artikkelen] (2023). Retraction notice to “A tropical soil (Ferralsol) identified in the northernmost part of the Mediterranean (Istria, Croatia)” [CATENA 224 (2023) 106955] (Catena (2023) 224, (S0341816223000462), (10.1016/j.catena.2023.106955)). CATENA. ISSN 0341-8162. 228. doi: 10.1016/j.catena.2023.107161. Fulltekst i vitenarkiv
• Svendby, Anne Kathrine; Osmundsen, Per Terje; Andersen, Torgeir Bjørge & Andresen, Arild (2023). Progressive faulting evolution in a transtensional basin; the Grunnevatnet fault, Western Norway. Fulltekst i vitenarkiv Vis sammendrag

  The Devonian basins in western Norway developed in a contintal environment above a crustal‐scale detachment in a strain field dominated by sinistral transtension. The observatons from the Kvamshesten basin are used to conceptualize scenarios for the basin evoluon. In the southwest, the unconformity below the basin is offset by synsedimentary faults, which show normal/ oblique separtiaon in the present configuraon. The largest is the SW‐NW striking Grunnevatnet Fault (GF), which is characterized by an apparent sinistral offset of >2 km offset along the SW basin‐margin, and just a few 10`s of meters in the north, where alluvial midfan lithofacies can be traced across the fault. This is interpreted as the most important evidence for syndeposional slip (Svendby 2011). The large apparent displacement gradient indicates a development different from many normal faults. The fault terminates against the top of the extensional Nordord Sogn Detachment Zone (NSDZ), providing addional evidence that the main acvity of the fault pre‐dated the last movements on the brile detachment. How can such a large change in fault displacement over such a short lateral distance be explained? We discuss the evoluon of the Grunnevatnet Fault in terms of scenarios where the GF is interpreted as active during different stages of the basin evoluon. Observations in the NW part of the basin indicates a pattern where the oldest part of the basin fill was rotated onto the flank of a syncline that grew laterally as units progressively onlapped basement towards the northeast. The Grunnevatnet fault may represent early deformation related to growth of the main detachment and associated core complex.

• Whattam, Jack; Svensen, Henrik Hovland; Midtkandal, Ivar; Callegaro, Sara & Jerram, Dougal Alexander (2023). Intermittent cessation and renewal of volcanism in the Oslo Rift revealed through detailed mapping and stratigraphy. Fulltekst i vitenarkiv
• Michalek, Jan; Atakan, Kuvvet; Ottermøller, Lars; Natvik, Øyvind; Lampe, Ove Daae & Fonnes, Gro [Vis alle 14 forfattere av denne artikkelen] (2023). EPOS-Norway Portal. Fulltekst i vitenarkiv
• Andersen, Torgeir Bjørge (2023). En Wilson-syklus og sporene av platetektonikk i norsk geologi. Fulltekst i vitenarkiv
• Hernandez, Jean-Alexis; Bethkenhagen, M.; Ninet, S.; French, M.; Benuzzi-Mounaix, A. & Datchi, F. [Vis alle 12 forfattere av denne artikkelen] (2023). Author Correction: Melting curve of superionic ammonia at planetary interior conditions (Nature Physics, (2023), 10.1038/s41567-023-02074-8). Nature Physics. ISSN 1745-2473. doi: 10.1038/s41567-023-02130-3. Fulltekst i vitenarkiv
• Shephard, Grace; Crameri, Fabio & Straume, Eivind Olavson (2023). Open graphics for open science; the s-Ink.org graphics repository. Fulltekst i vitenarkiv
• Kabanov, Pavel; Abdi, Wendy; Bilot, Igor; Boon, Annique van der; Gouwy, Sofie & Grasby, Stephen E. [Vis alle 11 forfattere av denne artikkelen] (2023). Geological and geochemical data from Mackenzie corridor. Part XI: New geochemical, magnetic susceptibility, and X-ray diffraction data from the Horn River Group (Devonian) in cores and outcrops south of Norman Wells, Northwest Territories. Natural Resources Canada. doi: 10.4095/331201. Fulltekst i vitenarkiv Vis sammendrag

  This report compiles previously unpublished analytical data from two cores and an outcrop section of the sedimentary rocks of Middle-Upper Devonian age bundled in the Horn River Group in central Mackenzie Valley between Norman Wells and Tulita. This includes a broad range of high-precision elemental geochemical data, carbon and oxygen stable isotope data, mineral composition based on X-ray diffraction data, pyrolysis data providing parameters of fossil organic matter, and magnetic siusceptibility measurements. These data are used in two recent publications. Scientific implications of this study shed light on redox systems in Devonian black-shale basins globally, including signatures and nature of multiple anoxic events, the conditions that were conductive for vigorous stocking and preservation of planktogenic organic matter in many shelfal basins of the world. This line of research aslo explores the greenhouse (warm and ice-free) state of Earth surface in the remote Past and therefore has relevance to predict the ultimate state of the global warming.

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