Publikationer

Abstract: Cavities (crypts) formed postmortally within conjoined valves of acrotretoid brachiopods from the Fimbuldal Formation (Cambrian, Miaolingian Series) of North Greenland contain phosphate encrustations of microbial threads, probably fungi. The planar relationship between these cryptoendolithic masses and the sediment that partially fills the brachiopod interiors defines palaeohorizontal surfaces within geopetal structures. These surfaces parallel the commissural plane, indicating that the dead shells lay in a hydronamically stable position on or within the bottom sediment at the time the geopetals were formed.

Keywords: Cryptoendoliths, geopetals, Cambrian, Miaolingian Series, North Greenland, Laurentia.

Address: John S. Peel, [john [dot] peel [at] pal [dot] uu [dot] se], Department of Earth Sciences (Palaeobiology), Uppsala University, Villavägen 16, SE–75236 Uppsala, Sweden. 

Abstract: The free-living part of the restricted bryozoan fauna in the Late Miocene (Tortonian) Gram Formation, Denmark is described. Four species are recorded: Cupuladria aff. biporosa, Lunulites voigti, Reussirella germinatio n. sp. and Gramipora laxevincta n. gen., n. sp. The new suborder Cupuladriina nov. is introduced. The concepts of ‘free-living’ vs. ‘free-lying’ colonies are discussed briefly, with three categories of ‘free-living’ colonies considered, all exemplified by the four free-living taxa in the Gram fauna.

Keywords: Bryozoa, functional morphology, taxonomy, new taxa, Cupuladriina.

Address: Eckart Håkansson (eckart [dot] hakansson [at] uwa [dot] edu [dot] au), School of Earth Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia; also: GeoMuseum Faxe, Rådhusvej 2, DK-4640 Faxe, Denmark, orcid.org/0000-0002-5045-5586. Sten Lennart Jakobsen, GeoMuseum Faxe, Rådhusvej 2, DK-4640 Faxe, Denmark. Antonietta Rosso (rosso@unict. it), Department of Biological, Geological and Environmental Sciences, University of Catania, Italy, orcid.org/0000-0001-5565-9513. Erik Thomsen, Department of Geoscience, University of Aarhus, Høegh-Guldbergs Gade 2, DK-8000 Aarhus C, Denmark.

Abstract: The systematic affinities of Palaeocentrotus boggildi within acanthomorph fishes have never been properly discussed. A comparative analysis of the skeletal anatomy of the genera Cyttus and Zeus was used by Kühne to support the placement of Palaeocentrotus within the zeiforms, despite certain features are completely different from those characteristic of zeiforms. Bonde (1966) was the first that recognised the lampridiform affinities of Palaeocentrotus and allocated the genus to its own family, Palaeocentrotidae. However, this hypothesis was not supported by a discussion of the relevant features to justify a possible relationship with the Lampridiformes. The anatomical survey of the known material of Palaeocentrotus boggildi presented here resulted in the identification of a suite of features that is regarded as diagnostic of the Lampridiformes, including: anterior palatine process absent, mesethmoid posterior to lateral ethmoids, elongate ascending premaxillary process longer than the alveolar process and inserting into the frontal vault, premaxilla and dentary edentolous, endopterygoid teeth absent, urohyal bearing a large ventral laminar expansion, second ural centrum free from fused first ural and preural centra and fused posteriorly to the upper hypural plate, presence of two supraneurals and of a single postcleithrum. The most striking feature of the Palaeocentrotidae, comprising only Palaeocentrotus and Natgeosocus, is the unique configuration of the dorsal fin wherein true spines occur exclusively in the central portion. This peculiar condition represents a further example of the remarkable plasticity of the acanthomorph median fins.

Keywords: Palaeocentrotidae, Paleogene, Ypresian, Natgeosocus, dorsal fin.

Address: Ane Elise Schrøder [aes [at] ign [dot] ku [dot] dk], Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark; also Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy [aneelise [dot] schroder [at] unito [dot] it] https://orcid.org/0000-0001-9371-400X. Bent Erik Kramer Lindow [cetotherium [at] hotmail [dot] com], Kalk/Østsjællands Museer, Østervej 2, 4640 Faxe, Denmark https://orcid.org/0000-0002-1864-4221. Giorgio Carnevale [giorgio [dot] carnevale [at] unito [dot] it], Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy http://orcid.org/0000-0002-3433-4127.

Abstract: New material of trilobites and agnostoids has been collected from in situ occurrences of the Miaolingian Exporrecta Conglomerate in Västergötland, Sweden, and from Pleistocene ice-rafted boulders of the Andrarum Limestone and Exporrecta Conglomerate in Denmark, which are assumed to derive from that region. Both units represent the lower part of the Lejopyge laevigata Zone. The erratic boulders of Andrarum Limestone consist of compact, light- to dark-grey, highly fossiliferous limestone, essentially identical to the Andrarum Limestone in southernmost Scandinavia (Skåne–Bornholm). To date, no in situ occurrences of this lithology have been documented from anywhere in Scandinavia north of Skåne. The new fossil material includes well-preserved specimens of Acontheus acutangulus, Corynexochus spinulosus and Dolichometopus svecicus. Notably, the new pygidia of these taxa show features not recorded in the respective type specimens, which are refigured here for comparison.

Keywords: Miaolingian, Sweden, Västergötland, Andrarum Limestone, Exporrecta Conglomerate, trilobites, agnostoids.

Address: Thomas Weidner [to [dot] we [at] paradis [dot] dk], DK-7130, Ravnholtvej 23, Rårup, DK 7130, Juelsminde, Denmark. Arne Thorshøj Nielsen [arnet [at] ign [dot] ku [dot] dk], Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark. Jan Ove R. Ebbestad [jan-ove [dot] ebbestad [at] em [dot] uu [dot] se], Museum of Evolution, Uppsala University, Norbyvägen 16, SE–752 36 Uppsala, Sweden.

Abstract: This is the first comprehensive description of late Oligocene otoliths from the northern North Sea Basin, i.e., the Norwegian–Danish Basin. More than 2100 otolith specimens had been collected from 17 localities in Denmark and from the erratic Sternberger Gestein of Mecklenburg, Germany. A total of 60 species have been identified from the Danish localities, of which 9 are new species, and four from the Sternberger Gestein and three further species are described from localities in the southern North Sea Basin that have previously remained as nomina nuda. The new species in the sequence of description are Sardinella mecklenburgensis, Palaeoesox scandicus, Paraulopus superstitius, Lampanyctus morsensis, Lampanyctus vilsundensis, Enchelyopus dybkjaerae, Palimphemus pinguis, Trisopterus brevicollum, Trisopterus cylindratus, Trisopterus weileri, Coelorinchus ignotus, Nomeus sternbergensis, Artediellus iutlandicus, Myoxocephalus aculeatus, Dapalis bradicae and Lophiodes sliwinskae. The faunal composition exhibits some substantial differences to well-known otolith assemblages of the southern North Sea Basin in western Germany, The Netherlands and Belgium. These differences are thought to be related to cooler water temperatures in the northern North Sea Basin during the late Oligocene compared to the postulated warm pool in the southern North Sea Basin. Certain localities in the northwestern region of Jutland (Denmark) were deposited in greater water depth on the lower shelf or upper bathyal zone and contained for the first time in the upper Oligocene otoliths of the mesopelagic Myctophidae and the bathybenthic Macrouridae in the North Sea Basin. In combining the knowledge of otoliths from the southern and northern parts of the basin, we arrive at an improved understanding of the evolution of bony fishes in the region during the late Oligocene, a time when the North Sea Basin had transformed into a cul-de-sac basin open only to the north. Climatic changes such as cold pulses (Oi-2 and Mi-1 events) and warm influx (Asterigerina Horizon) are reflected in the composition of the fish fauna. The enhanced otolith database enabled us to establish a consistent, formal otolith zonation for the Oligocene of the North Sea Basin based on gadid otoliths. Moreover, we performed 87Sr/86Sr isotope analyses for certain localities in addition to those published, and as a result, we propose to expand the range of the Brejning Formation from about 22.4 Ma to 26.0 Ma, therewith extending into the basal Miocene.

Keywords: Otoliths, upper Oligocene, Brejning Formation, Denmark, Sternberger Gestein, otolith stratigraphy.

Address: Werner W. Schwarzhans [wwschwarz [at] aol [dot] com], Zoological Museum, Natural History Museum of Denmark, Universitetsparken 15, DK – 2100 Copenhagen Ø, Denmark, and Ahrensburger Weg 103, D-22359 Hamburg, Germany, http://orcid.org/0000-0003-4842-7989. Kai Ingemann Schnetler [ingemann [at] schnetler [dot] dk], Fuglebakken 14, Stevnstrup, DK-8870 Langå, Denmark, https://orcid.org/0009-0000-2298-2875. Kent Albin Nielsen [kent [at] ksjm [dot] dk], Tingskoven 22, DK -7330 Brande, Denmark, https://orcid.org/0000-0002-5800-5774. Mogens Stentoft Nielsen [rimo [at] mail [dot] dk], Dankvart Drejers Vej 42, DK-5230, Odense M, Denmark. Henrik Madsen [henrik [dot] madsen [at] museummors [dot] dk], Fossil and Mo-clay Museum, Museum Mors, Skarrehagevej 8, DK-7900, Nykøbing Mors, Denmark.

Abstract: The majority of Palaeogene coprolite localities are in nonmarine strata. We describe a new, large and diverse ichnofauna of small-sized vertebrate and invertebrate coprolites ranging from 0.5 – 14 mm in length, from the marine Eocene of Denmark that includes several new ichnotaxa. The ichnofauna derives from the early – middle Eocene Røsnæs Clay Formation (R6) and Lillebælt Clay Formation (L2) in the active claypit at Hinge, middle Jylland, Denmark. The vertebrate coprolites represent six morphotypes and 6 new ichnotaxa – Kylindrocopros hingeensis igen. et isp. nov., Kathemacopros duffini igen. et isp. nov., Osteocopros frandseni igen. et isp. nov., Commacopros dentziendiasae igen. et isp. nov., Kranocopros lucasi igen. et isp. nov. and Hingecopros lillebæltensis igen. et isp. nov. We recognize a new ichnospecies of Kylindrocopros, K. rakshitae igen. et isp. nov. from the Eocene of the United States. Funiculocopros sinuosus igen. et isp. nov. is a member of the invertebrate coprolite ichnofamily Lumbricariidae and is the only post-Mesozoic example. This assemblage includes a rare co-occurrence of vertebrate and invertebrate coprolites.

Keywords: Coprolites, vertebrate, invertebrate, Eocene, Denmark.

Address: Adrian P. Hunt [ahunt [at] flyingheritage [dot] org], Flying Heritage and Combat Armor Museum, 3407 109th SW, Everett, WA 98204, USA. Kent Albin Nielsen [kent [at] ksjm [dot] dk], Tingskoven 22, DK-7330 Brande, Denmark. Jesper Milàn [jesperm [at] oesm [dot] dk], KALK/ Museums of East Zealand, Østervej 2, DK-4640 Faxe, Denmark.

Abstract: The serpulid palaeocommunity of the Late Oligocene Brejning Formation in Jylland (Jutland) is described and discussed based on specimens collected at Vilsund, Mogenstrup, Hinge, Aarhus, and Nørre Vissing localities. The serpulid species are: Protula cf. septaria (Giebel, 1858), Filogranula mogenstrupensis sp. nov., Placostegus vilsundensis sp. nov., Placostegus cf. erectus (Nielsen, 1931), and Placostegus cf. bilobatus (von Koenen, 1891). The semi-ordered irregularly oriented prismatic microstructure (SOIOP) of the tube wall of Protula cf. septaria (Giebel, 1858) is examined and discussed for the first time. These serpulids lived in a calm, normal marine palaeoenvironment below storm wave base. Furthermore, the first known vermetid gastropod from the Late Oligocene of Jylland, Vermetus jyllandensis sp. nov., is introduced, and its shell microstructure is discussed.

Keywords: Serpulidae, Vermetidae, Brejning Formation, Upper Oligocene, Jutland, Denmark, skeletal microstructure.

Address: Tomáš Kočí [protula [at] seznam [dot] cz] Ivančická 581, Prague 9 – Letňany, 19900, Czech Republic, and Paleontological Department of Natural History Museum, National Museum at Prague, Cirkusová 1740, 193 00 Prague 9 Horní Počernice, Czech Republic, and Institute for Palaeobiology and Evolution, Novi trg 59, 1241 Kamnik, Slovenia. Kai Ingemann Schnetler [ingemann [at] schnetler [dot] dk], Fuglebakken 14, Stevnstrup, DK-8870 Langå, Denmark. Henrik Madsen [henrik [dot] madsen [at] museummors [dot] dk], Museum Mors, The Fossil and Mo-clay Museum, Skarrehagevej 8, 7900 Nykøbing, Denmark. Manfred Jäger [langstein. jaeger [at] web [dot] de], Lindenstrasse 53, 72348 Rosenfeld, Germany. Lenka Váchová [lenka [dot] vachova [at] nm [dot] cz], Paleontological Department of Natural History Museum, National Museum at Prague, Cirkusová 1740, 193 00 Prague 9 Horní Počernice, Czech Republic. Martina Kočová Veselská [kocovam [at] gli [dot] cas [dot] cz], Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Prague 6, Czech Republic and Institute for Palaeobiology and Evolution, Novi trg 59, 1241 Kamnik, Slovenia.

Abstract: Microcommacopros is suggested as a replacement name for the ichnogenus Commacopros Hunt, Nielsen & Milàn, 2026, from the Eocene Lillebælt Clay Formation, to avoid confusion with the ichnogenus Kommacopros Duffin & Ward, 2025, from the Late Cretaceous of Marocco, as they share the same etymological root, but are morphologically different.

Keywords: Coprolites, vertebrate, invertebrate, Eocene, Denmark

Address: Adrian P. Hunt [ahunt [at] flyingheritage [dot] org], Flying Heritage and Combat Armor Museum, 3407 109th SW, Everett, WA 98204, USA. Kent Albin Nielsen [kent [at] ksjm [dot] dk], Tingskoven 22, DK-7330 Brande, Denmark. Jesper Milàn [jesperm [at] oesm [dot] dk], KALK/ Museums of East Zealand, Østervej 2, DK-4640 Faxe, Denmark.

Abstract: The Putoq Intrusion is a small (8 × 4 km) body of distinctive rocks that intruded Julianehåb Igneous Complex granitoids close to Qaqortoq in SW Greenland. It comprises an outer hornblende monzonite surrounding an inner hornblende syenite. Evidence for mingling with mafic magmas is present in both the monzonite and syenite. The rocks are metaluminous and quartz-bearing. Zircon U-Pb dating of two samples yields an age of c. 1.81 Ga, indicating a link to c. 1.81–1.79 Ga rocks of the younger portion of the Julianehåb Igneous Complex, and that the Putoq Intrusion is unrelated to the c. 1.1 Ga Gardar Province intrusions to the north. The Putoq Intrusion is similar to the Julianehåb Igneous Complex in that it has trace element patterns typical of crustal rocks linked to subduction, and initial 87Sr/86Sr and εNd values of 0.7027 to 0.7044 and +0.6 to –1.4, respectively. The higher K2O contents, more alkalic and ferroan compositions of the Putoq Intrusion are similar to contemporaneous granitoids of the Adlavik Domain in the Makkovik Province of Labrador, Canada. However, the Adlavik rocks are distinguished from the Putoq Intrusion by higher concentrations of high field strength elements. The Putoq Intrusion is therefore considered to represent an alkalic component of the Julianehåb Igneous Complex, potentially formed by fractionation of mafic magmas derived from melting of an enriched lithospheric mantle source.

Keywords: SW Greenland, Syenite, Geochronology, Geochemistry, Julianehåb Igneous Complex, Ketilidian Orogen.

Address: Tod Waight [todw [at] ign [dot] ku [dot] dk], Rikke Vestergaard, Merel Onderwater, Mariana Iwasaki, Panormitis Chaskas, Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark. Benjamin Heredia, Tonny B. Thomsen, GEUS, Øster Voldgade 10, 1350 Copenhagen K, Denmark. MO also at Centre of Star and Planet Formation, Globe Institute, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark.

Abstract: The slender tubular conch and associated operculum comprising Hyolithellus micans, as originally proposed from the lower Cambrian of New York State, are described from the lower Cambrian Kap Troedsson Formation of North Greenland. Following a review of the nomenclative history, Discinella, also first described from New York State for the operculum without any assigned species, is regarded as a junior synonym of Hyolithellus micans as it was originally proposed. Hyolithellus and Discinella are generally employed as separate genera for just the conch and the operculum, respectively, a pragmatic approach since the operculum and conchs are rarely associated. The Kap Troedsson Formation samples are unusual on account of the collective occurrence of the phosphatic conchs and opercula with circular attachment scars and holdfasts, which supports their interpretation as comprising a single sedentary operculate annelid that was attached to hard substrates.

Keywords: Annelid, Kap Troedsson Formation, Cambrian, North Greenland, Laurentia.

Address: John S. Peel, [john [dot] peel [at] pal [dot] uu [dot] se], Department of Earth Sciences (Palaeobiology), Uppsala University, Villavägen 16, SE–75236 Uppsala, Sweden.

Abstract: In 2017 a 75 g meteorite was recovered from a roof cavity of a summer house annex at Dueodde on the Danish island of Bornholm. Although the fall of Denmark’s 8th recovered meteorite was not witnessed, the meteorite could have only resided there for a few years due to the age of the annex. We report the first detailed micro-analytical analysis of the mineral textures and mineral chemistries of this little-studied meteorite and attempt to classify the class, metamorphic grade and weathering state. Dueodde is a small, slightly abraded fusion-encrusted meteorite that has a pale medium to coarse-grained orthopyroxene-olivineplagioclase-metal-rich interior. The compositional range of olivine (Fa_16-20; where Fa = 100*Fe/(Fe+Mg)) and orthopyroxene (Fs_17-18; where Fs = 100*Fe/(Fe+Mg)) in matrix and chondrules confirms Dueodde to be an H class ordinary chondrite. Chemical element maps highlight the occurrence of barred, radial and porphyritic chondrules, some of which are up to c. 3 mm in diameter. These maps also reveal that all three types of chondrule are distinctly depleted in metal minerals compared to the matrix, with this texture interpreted to represent metal expulsion during chondrule formation prior to incorporation and metamorphism in the parent body. The preservation of chondrule textures, the small variation in olivine Fa across the entire sample, and the plagioclase compositions suggest that Dueodde experienced metamorphism of grade 5 whilst in the parent body.

Keywords: Meteorite, H5, Bornholm, classification.

Address: Mia R.E. Boothroyd, Charlotte R. Håkansson, Anna W. Jensen, Rasmus Andreason, James M.
Scott [jscott [at] geo [dot] au [dot] dk], Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, Aarhus, Denmark.

Abstract: A rich brachiopod fauna has been found in the topmost Maastrichtian chalk immediately below the Cretaceous–Paleogene (K–Pg) boundary clay at Stevns Klint, Denmark – the UNESCO World Heritage Site for the boundary. The brachiopods were obtained from the washing residue of a 25 kg bulk sample, Holtug-1. They represent the latest known Mesozoic brachiopod fauna, which lived in the Late Cretaceous Chalk Sea of northern Europe immediately before the cataclysmic boundary incident. The fauna comprises 28 mainly micromorphic species represented by 1967 individuals. This is more than the faunas obtained from the otherwise most benthos-rich parts of the Upper Cretaceous Chalk Group in terms of both number of species (richness) and individuals and includes the full range of morphological adaptations to life on the fine-grained seafloor recognised in the literature. The sample shows the highest richness compared to stratigraphically lower samples from Stevns Klint and is higher than in all other Danish sections where the K-Pg boundary is exposed. It is also higher than the richest samples from the densely sampled older Maastrichtian successions at Møns Klint, Denmark and at Hemmoor, northern Germany. The Chalk Sea was a unique macro-habitat for about 34 million years and the last Mesozoic brachiopods from Holtug-1 thus represent a climax in the long evolution of the very specialized brachiopod fauna of the chalk.

Keywords: Brachiopoda, Mesozoic, Maastrichtian, chalk, richness, Denmark.

Address: Finn Surlyk [finns [at] ign [dot] ku [dot] dk] Department of Geosciences and Natural Resource Management, University of Copenhagen. Øster Voldgade 10, 1350 Copenhagen K, Denmark. Sten Lennart Jakobsen [Stenlennart [at] yahoo [dot] dk], KALK/Østsjællands Museer, Rådhusvej 2, DK-4640, Faxe, Denmark. Mette Hofstedt [hofstedt [at] gmail [dot] com], Ballesvej 65, 8543 Hornslet.

Abstract: The Maastrichtian chalk at Hemmoor in NW Germany contains a rich brachiopod fauna. A total of 29 species represented by about 10,000 individuals is obtained from washed bulk samples. The total number reaches 34 when 5 very rare, mainly fragmented species are added. The brachiopod fauna of the Maastrichtian chalk of northern Europe is also known from Denmark, Germany, Sweden, Poland, Belgium, the Netherlands and England. The Hemmoor succession represents the upper lower – lower upper Maastrichtian. It is biostratigraphically zoned by means of brachiopods, belemnites, ammonites, echinoids and bivalves. The brachiopod fauna allows recognition of the upper lower Maastrichtian pulchellus-tenuicostata, tenuicostata-semiglobularis and lower upper Maastrichtian semiglobularis-humboldtii brachiopod zones, allowing detailed correlation with the chalk in surrounding regions, notably Denmark and Rügen. The fauna is dominated by micromorphic species and three different ecological assemblages are recognized: a ‘standard’ chalk assemblage dominated by micromorphic species but also containing medium- and large-sized species, an assemblage comprising only micromorphic species, and an assemblage characterized by micromorphic species associated with medium-sized hemispherical species. The assemblages are interpreted as reflecting different water depths, availability and nature of substrates.

Keywords: Brachiopod biostratigraphy, Hemmoor Formation, NW Germany.

Address: Finn Surlyk [finns [at] ign [dot] ku [dot] dk], Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark. Ane Elise Schrøder [aes [at] ign [dot] ku [dot] dk], Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark; also Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy. https://orcid.org/0000-0001-9371-400X.

Abstract: Understanding the ground thermal regime in permafrost regions is important because seasonal and climatic temperature variations are related to human risks. Small local variations in the ground thermal regime can be accelerated by positive feedback loops leading to accelerated permafrost degradation. In central West Greenland, we hypothesize that mafic Kangâmiut dykes and their gneissic host rocks have contrasting thermal properties, and that it can lead to differences in the ground thermal regime across very small distances. To test this, we measure the thermal properties of gneiss and a Kangâmiut dyke as well as minor pegmatite and supracrustal rock in a drill core (GIOS2023-01) near Kangerlussuaq. Temperature measurements from the  corresponding borehole allow us to calculate a local heat flux of 48 ± 4 to 51 ± 4 mW m^–2. To understand the thermal conductivity under in situ conditions, we use ultrasonic P- and S-wave velocity as a proxy to evaluate its dependence on pore fluid and lithostatic pressure. Together, thermal properties and heat flux provide input to transient numerical thermal models that explore the ground thermal regime under different scenarios. The thermal properties of the gneiss (k = 3.1–3.4 W m^–1 K^–1, ϱ = 2603–2703 kg m^–3, c_P = 754–825 J kg^–1 K^–1) is clearly different from those of the amphibolitic dyke (k = 2.5–4.6 W m^–1 K^–1, ϱ = 3049–3088 kg m^–3, c_P = 660–672 J kg^–1 K^–1). One supracrustal sample (k = 3.03 W m^–1 K^–1, ϱ = 2926 kg m^–3, c_P = 695 J kg^–1 K^–1) is somewhat similar to the dyke, whereas a quartz-rich pegmatite is highly conductive (k = 6.9 W m^–1 K^–1, ϱ = 2622 kg m^–3, c_P = 893 J kg^–1 K^–1). Although ultrasonic velocities indicate that elastic moduli increase with axial stress and vary between gneiss and dyke, and between wet and dry state, these mechanical effects translate into negligible changes in thermal conductivity. For exposed bedrock, transient numerical thermal models suggest that the active layer thickness is several decimetres thicker in gneiss than in the dyke, and that the difference is in the order of metres when comparing gneiss or dyke to the pegmatite. With increasing sediment thickness overlying the bedrock, the difference in active layer thickness decreases. At a certain sediment thickness (~0.75 m with the chosen sediment properties), the active layers thicknesses reverse, i.e. active layers in the dyke are thicker than in gneiss (and pegmatite). This shift reflects two opposite effects: with no or little sediment cover, the relatively dense dyke is resistant to annual temperature variations. As sediment thickness increase, more of the temperature variations occurs in the sediment, and the dyke act as a heat sink, causing high temperature gradients and fast heat diffusion. As the sediment thickness exceeds the active layer thickness, the difference in active layer thickness between lithologies decreases to few centimetres. This small difference persists for several metres of sediment cover (~4 m with the chosen sediment properties). Metre-scale differences in active layer thickness have direct consequences for stability of rock slopes. Although centimetre-scale differences in active layer thickness will have limited influence on the stability of the sediment, it can accelerate by positive feedback loops. This insight could be validated in future field studies and provide input to predictive models of permafrost instability.

Keywords: West Greenland, Kangâmiut dyke, GIOS2023-01, thermal properties, elastic moduli, permafrost, CryoGrid.

Address: O. Skursch [olsku [at] dtu [dot] dk] and T. Ingeman-Nielsen [thin [at] dtu [dot] dk] Department of Environmental and Resource Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark; E. Proestakis [ermpr [at] dtu [dot] dk] Danish Offshore Technology Center, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

Abstract: Newly discovered fossil fruits and seeds from the lower part of Member L2 of the Lillebælt Clay Formation at Hinge clay pit, Denmark, provide the first diverse plant macrofossil assemblage from this unit. The material includes 39 specimens retrieved by sieving of approx. 5000 kg of a thin sapropel layer and adjacent clay occurring within the lower part of the Azolla-bearing interval and is dated to the latest Ypresian, Chron C22n, approximately 49 Ma. The assemblage includes named or tentatively named taxa assigned to five species in two (possibly three) genera of Vitaceae; Eurya sp. and Cleyera sp. (Pentaphylaceae); Rhamnospermum bilobatum (incertae sedis); Mastixiaceae; Magnoliaceae; Icacinaceae and 20 additional taxa of seeds, fruits or endocarps for which the modern relatives are unclear. The assemblage is notable for its occurrence in an offshore, bathyal depositional environment, implying long-distance transport from surrounding land areas into the eastern North Sea Basin. Comparison with Eocene floras from the United Kingdom and Germany (Messel) shows both similarities and striking differences. Several families common in coeval floras, including Menispermaceae and others, are not recorded in the Hinge assemblage. These absences are probably due mainly to taphonomic modification of the assemblage during the transport and early diagenesis, but rarity of taxa and preparation technique may also play a role. Other explanations for differences may be differing ages and/or ecologic distributions of the compared floras. The assemblage provides a rare window into late early Eocene vegetation around the North Sea Basin while also emphasizing the strong taphonomic filtering that shaped the fossil record at Hinge.

Keywords: Fruits, Seeds, Eocene, Lillebælt Clay Formation, Denmark, North Sea Basin.

Address: Kent A. Nielsen [kent [at] ksjm [dot] dk], Tingskoven 22, DK-7330 Brande, Denmark, Orcid.org/0000-0002-5800-5774. Margaret E. Collinson [M [dot] Collinson [at] rhul [dot] ac [dot] uk], Department of Physical Sciences and Engineering, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK. Claus Heilmann-Clausen [claus [dot] heilmann [at] geo [dot] au [dot] dk], Institut for Geoscience, Aarhus Universitet, Høegh-Guldbergs Gade 2, DK-8000 Aarhus C, Denmark. Orcid.org/0000-0002-5894-7139.

Abstract: Ichthyosaurs were widespread and diverse across Europe from the Triassic to the beginning of the late Cretaceous. However, they are relatively rare within Scandinavia, with specimens only known from Arctic Norway. In Denmark, plesiosaur fossils are known from the Jurassic of the island of Bornholm, but no ichthyosaur remains have ever been published either in situ or ex situ. Here we report, for the first time, an ichthyosaur vertebra found in a loose block on the shore at Lodbjerg Klint in western Jylland, and a second block containing ribs from an indeterminate marine reptile, most likely a plesiosaur. The vertebra can be identified as originating from the anterior portion of the tail in a thunniform ichthyosaur and shows similarity to several Jurassic taxa including Ichthyosaurus communis, Eurhinosaurus longirostris, Temnodontosaurus trigonodon and Ophthalmosaurus, although an exact determination is not possible. The most prolific sites for ichthyosaurs in the neighbouring countries, in the UK and Germany, are ruled out as a source due to long distance, and lack of glacial transport from these directions. We postulate the origin of the specimen is from Jurassic outcrops within the Skagerrak–North Sea region, transported by south and south-westerly flow of Pleistocene glaciers.

Keywords: glacial transport, ichthyosaur, marine reptile, Jurassic, vertebra, Pleistocene.

Address: Laura J. Cotton [laura [dot] cotton [at] snm [dot] ku [dot] dk], Natural History Museum Denmark, Sølvgade 83, 1307 København K, Denmark. Lotta Dreyer [lotta [dot] dreyer [at] smnk [dot] de], State Museum of Natural History Karlsruhe, Erbprinzenstr. 13, 76133 Karlsruhe, Germany. Lene L. Delsett [l [dot] l [dot] delsett [at] nhm [dot] uio [dot] no], Natural History Museum, University of Oslo, Sars’ gate 1, 0562 Oslo, Norway.

Abstract: A second occurrence of Kordesphecia nyeboensis is reported from the Aftenstjernesø Formation (Cambrian Series 2) at the head of Nordenskiöld Fjord, North Greenland, providing significant new information concerning the morphology of an enigmatic microfossil first described from Nyeboe Land. A rhizoid (holdfast), a robust, plated stem and a crown with distinctive, radiating, rhombic cells are recognized in a relatively complete, sub-cylindrical juvenile specimen. The calcified thallus in larger examples is shown to have developed robust, trumpet-shaped branches or to have divided dichotomously. The new morphological details support the original suggestion that Kordesphecia may be a stem group dasycladalean green alga.

Keywords: Green algae, ?Dasycladales, Cambrian, Aftenstjernesø Formation, Greenland, Laurentia.

Address: John S. Peel, [john [dot] peel [at] pal [dot] uu [dot] se], Department of Earth Sciences (Palaeobiology), Uppsala University, Villavägen 16, SE–75236 Uppsala, Sweden.