Contents
Schovsbo, N.H., Nielsen, A.T., Harstad, A.O. & Bruton, D.L. 02-02-2018.
Stratigraphy and geochemical composition of the Cambrian Alum Shale Formation in the Porsgrunn core, Skien–Langesund district, southern Norway.
Marzola, M., Mateus, O., Milàn, J. & Clemmensen, L.B. 03-03-2018.
A review of Palaeozoic and Mesozoic tetrapods from Greenland.
Cuny, G. & Stemmerik, L. 06-03-2018.
New fossil fish microremains from the Upper Carboniferous of eastern North Greenland.
Hovikoski, J., Pedersen, G.K., Alsen, P., Lauridsen, B.W., Svennevig, K., Nøhr-Hansen, H., Sheldon, E., Dybkjær, K., Bojesen-Koefoed, J., Piasecki, S., Bjerager, M. & Ineson, J. 18-06-2018.
The Jurassic–Cretaceous lithostratigraphy of Kilen, Kronprins Christian Land, eastern North Greenland.
Bennike, O. & Mortensen, M.F. 29-06-2018.
A multi-disciplinary macrofossil study of late glacial to early Holocene sediments from Søndre Kobberdam, Hareskovene, Denmark.
Erlström, M., Boldreel, L.O., Lindström, S., Kristensen, L., Mathiesen, A., Andersen, M.S., Kamla, E. & Nielsen, L.H. 04-07-2018.
Hjuler, M.L., Hansen, V.F. & Fabricius, I.L. 31-08-2018.
Souza, P.E., Kroon, A. & Nielsen, L. 07-09-2018.
Milàn, J., Rasmussen, E.S. & Dybkjær, K. 10-09-2018.
A crocodilian coprolite from the lower Oligocene Viborg Formation of Sofienlund Lergrav, Denmark.
Glad, A.C., Willumsen, M.E., Boldreel, L. O. & Clemmensen, L.B., 26-09-2018.
Myrvold, K.S., Milàn, J. & Rasmussen, J.A. 04-10-2018.
Bennike, O. 26-10-2018.
Book Review: Fischer, A. & Pedersen, L. (eds) 2018: Oceans of Archaeology. Jysk Arkæologisk Selskabs Skrifter vol. 101, 237 pp. ISBN 978-87-93423-18-3. Aarhus: Aarhus Universitetsforlag.
Weidner, T. & Ebbestad, J.O.R. 6-11-2018.
Malchyk, O. & Machalski, M. 22-11-2018.
Nielsen, A.T., Schovsbo, N.H., Klitten, K., Woollhead, D. & Rasmussen, C.M.Ø. 19-12-2018.
Stratigraphy and geochemical composition of the Cambrian Alum Shale Formation in the Porsgrunn core, Skien–Langesund district, southern Norway
Schovsbo, N.H., Nielsen, A.T., Harstad, A.O. & Bruton, D.L. 2018. Stratigraphy and geochemical composition of the Cambrian Alum Shale Formation in the Porsgrunn core, Skien–Langesund district, southern Norway.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 1–20. ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-01
Abstract: The fully cored BHD-03-99 borehole (hereafter referred to as the Porsgrunn borehole and core) penetrated Ordovician and Cambrian strata in the Skien–Langesund district, southern part of the Oslo region in Norway. Hand-held X-ray fluorescence (HH-XRF) measurements combined with spectral gamma ray and density core scanning of the Middle Cambrian – Furongian Alum Shale Formation have been made and compared with similar measurements obtained on Alum Shale cores from Scania (southernmost Sweden) and Bornholm (Denmark). The Porsgrunn drill site is located in an area that was only mildly overprinted by Caledonian tectonics and represents one of the few sites in the Oslo area where a nearly untectonised sedimentary succession can be studied in terms of thickness and geochemistry. The Alum Shale Formation is 28.8 m thick in the Porsgrunn core, excluding the thickness of five 0.9–5.5 m thick dolerite sills of assumed Permian age. In the Alum Shale Formation the bulk densities are around 2.7 g/cm3 with a slightly decreasing trend up through the formation. The shale has total organic carbon (TOC) values up to 14 wt%, which is comparable to the TOC levels for the Alum Shale elsewhere in the Oslo area and for dry gas matured Alum Shale in Scania and Bornholm. The basal Furongian is characterised by a gamma ray low and an increase in Mo interpreted to reflect the Steptoean Positive Carbon Isotope Excursion (SPICE) event. The Porsgrunn core data suggest that the Mo concentration remained high also after the SPICE event. Characteristic, readily identified features in the gamma log motif are named the Andrarum gamma low (AGL), base Furongian gamma low (BFGL), Olenus triple gamma spike (OTGS) and the Peltura gamma spike (PGS). No Lower Ordovician Alum Shale is present. The 14.8 m thick Furongian part of the Alum Shale represents the Olenus, Parabolina, Leptoplastus, Protopeltura and Peltura trilobite superzones judging from log-stratigraphic correlations to Scania and Bornholm. The Middle Cambrian interval is 14.0 m thick and includes the Exsulans Limestone Bed and 1.4 m of quartz sandstone. A 0.3 m thick primary limestone bed may be an equivalent to the Andrarum Limestone Bed. The succession represents the Paradoxides paradoxissimus and P. forchhammeri superzones. The Alum Shale Formation rests atop the 13.0 m thick Lower Cambrian Stokkevannet sandstone (new informal name) that in turn directly overlies the basement. Overall, the stratigraphic development of the comparatively thin Alum Shale Formation resembles the condensed sequence seen on Bornholm.
Keywords: Porsgrunn, Alum Shale, Cambrian, Correlation, Scandinavia, Geochemistry.
Addresses:
Niels Hemmingsen Schovsbo, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Arne Thorshøj Nielsen, Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen
K, Denmark.
Andreas Olaus Harstad, Norges Geotekniske Institutt (NGI), Sognsveien 72, N-0806 Oslo, Norway.
David L. Bruton, Natural History Museum (Geology), University of Oslo, Postboks 1172 Blindern, NO-0318 Oslo, Norway.
Top S
A review of Palaeozoic and Mesozoic tetrapods from Greenland
Marzola, M., Mateus, O., Milàn, J. & Clemmensen, L.B. 2018. A review of Palaeozoic and Mesozoic tetrapods from Greenland.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 21–46.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-02
Abstract: This article presents a synthesis of Palaeozoic and Mesozoic fossil tetrapods from Greenland, including an updated review of the holotypes and a new photographic record of the main specimens. All fossil tetrapods found are from East Greenland, with at least 30 different known taxa: five stem tetrapods (Acanthostega gunnari, Ichthyostega eigili, I. stensioi, I. watsoni, and Ymeria denticulata) from the Late Devonian of the Aina Dal and Britta Dal Formations; four temnospondyl amphibians (Aquiloniferus kochi, Selenocara groenlandica, Stoschiosaurus nielseni, and Tupilakosaurus heilmani) from the Early Triassic of the Wordie Creek Group; two temnospondyls (Cyclotosaurus naraserluki and Gerrothorax cf. pulcherrimus), one testudinatan (cf. Proganochelys), two stagonolepids (Aetosaurus ferratus and Paratypothorax andressorum), the eudimorphodontid Arcticodactylus, undetermined archosaurs (phytosaurs and both sauropodomorph and theropod dinosaurs), the cynodont Mitredon cromptoni, and three mammals (Haramiyavia clemmenseni, Kuehneotherium, and cf. ?Brachyzostrodon), from the Late Triassic of the Fleming Fjord Formation; one plesiosaur from the Early Jurassic of the Kap Stewart Formation; one plesiosaur and one ichthyosaur from the Late Jurassic of the Kap Leslie Formation, plus a previously unreported Late Jurassic plesiosaur from Kronprins Christian Land. Moreover, fossil tetrapod trackways are known from the Late Carboniferous (morphotype Limnopus) of the Mesters Vig Formation and at least four different morphologies (such as the crocodylomorph Brachychirotherium, the auropodomorph Eosauropus and Evazoum, and the theropodian Grallator) associated to archosaurian trackmakers are known from the Late Triassic of the Fleming Fjord Formation. The presence of rich fossiliferous tetrapod sites in East Greenland is linked to the presence of well-exposed continental and shallow marine deposits
with most finds in terrestrial deposits from the Late Devonian and the Late Triassic.
Keywords: Greenland, tetrapoda, marine reptiles, archosauria, trace fossils.
Addresses:
Marco Marzola, GeoBioTec, Departamento de Ciências da Terra, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal; also Department of Geosciences and Natural Resource Management, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark; also Museu da Lourinhã, Rua João Luís de Moura, 95, 2530-158 Lourinhã, Portugal; also Geocenter Møns Klint, Stengårdsvej 8, DK-4751 Borre, Denmark.
Octávio Mateus, GeoBioTec, Departamento de Ciências da Terra, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal; also Museu da Lourinhã, Rua João Luís de Moura, 95, 2530-158 Lourinhã, Portugal.
Jesper Milàn, Geomuseum Faxe, Østsjællands Museum, Østervej 2, DK-4640 Faxe, Denmark; also Natural History Museum of Denmark, Øster Voldgade 5–7, DK-
1350 Copenhagen K., Denmark.
Lars B. Clemmensen, Department of Geosciences and Natural Resource Management, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Download PDF (6,17 Mb) TopNew fossil fish microremains from the Upper Carboniferous of eastern North Greenland.
Cuny, G. & Stemmerik, L. 2018. New fossil fish microremains from the Upper Carboniferous of eastern North Greenland.
© 2018 by Bulletin of the Geological Society of Denmark, vol. 66, pp. 47-60.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-03
Abstract:
The Moscovian of eastern North Greenland has yielded an assemblage dominated by teeth and dermal denticles of chondrichthyans with rarer teeth of actinopterygians. The rather poor preservation of the material precludes precise identification but the following taxa have been recorded: Adamantina foliacea, Bransonella spp., Denaea sp., “Stemmatias” simplex, Lagarodus specularis, Actinopterygii indet., as well as teeth probably belonging to new genera of Heslerodidae, ?Protacrodontidae and Hybodontiformes. This fauna appears therefore quite endemic. The abundance of Bransonella and durophagous chondrichthyans is in accordance with the shallow marine depositional environment. The record of a ?protacrodontid is possibly the youngest one for this taxon.
Keywords: Greenland, Carboniferous, Moscovian, Foldedal Formation, sharks, euchondrocephals.
Addresses:
Gilles Cuny, Université de Lyon, UCBL, ENSL, CNRS, LGL-TPE, F-69622 Villeurbanne, France.
Lars Stemmerik, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, DK-1350 København K, Denmark; also The University Centre in Svalbard (UNIS), Longyearbyen, Norway.
Download PDF (5,61 Mb) TopThe Jurassic–Cretaceous lithostratigraphy of Kilen, Kronprins Christian Land, eastern North Greenland
Hovikoski, J., Pedersen, G.K., Alsen, P., Lauridsen, B.W., Svennevig, K., Nøhr-Hansen, H., Sheldon, E., Dybkjær, K., Bojesen-Koefoed, J., Piasecki, S., Bjerager, M. & Ineson, J. 2018. The Jurassic–Cretaceous lithostratigraphy of Kilen, Kronprins Christian Land, eastern North Greenland.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 61–112.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-04
Abstract:
Kilen, Kronprins Christian Land, contains the thickest and stratigraphically most complete Jurassic and Cretaceous sediment succession in North Greenland. This study revises and formalises the lithostratigraphic framework of these deposits. The work is based on recent extensive stratigraphic field work supplemented by photogeological mapping and biostratigraphic studies, and builds on the earlier stratigraphic work conducted mainly in the 1980s and 1990s. According to the new stratigraphic scheme, the more than 500 m thick Jurassic succession is divided into four formations. The poorly dated Gletscherport Formation comprises lagoonal heterolithic sandstones. The Mågensfjeld and Birkelund Fjeld Formations consist of shallow marine fine-grained sandstones of Bajocian–Bathonian and Kimmeridgian age, respectively. The Kuglelejet Formation comprises mainly shallow marine sandy mudstone and sandstone of Volgian age and includes the mudstone-dominated Splitbæk Member. The Lower Cretaceous interval is estimated to be more than 1500 m thick and is divided into three formations. The Dromledome Formation comprises deep shelf to offshore transition, black mudstones of late Ryazanian to Hauterivian age. It is erosively overlain by unfossiliferous, fluvial and estuarine sandstones of the Lichenryg Formation. The overlying, late Aptian to middle Cenomanian Galadriel Fjeld Formation comprises six members, of which the Tågekyst and Kangoq Ryg Members occur in the Gåseslette area, whereas the Pil, Valmue, Stenbræk and Hondal Members occur in the Kilen Fjelde area. The Galadriel Fjeld Formation is characterised by interbedded mudstones and sandstones from offshore–shoreface environments. The 650 m thick Upper Cretaceous succession is assigned to the Sølverbæk Formation, which is undivided in the Gåseslette area and divided into the Skalbæk and Scaphitesnæse Members in the Kilen Fjelde area. The Sølverbæk Formation is dominated by marine mudstones and sandstonemudstone heteroliths of late Cenomanian to Santonian age. The new lithostratigraphic framework and significant biostratigraphic advances allow a closer correlation of the Mesozoic units between North Greenland and other Arctic basins.
Keywords: Lithostratigraphy, Mesozoic, Jurassic, Cretaceous, Kilen, North Greenland, Wandel Sea Basin.
Addresses:
Jussi Hovikoski, Gunver K. Pedersen, Peter Alsen, Kristian Svennevig, Henrik Nøhr-Hansen, Emma Sheldon, Karen Dybkjær, Jørgen Bojesen-Koefoed, Morten Bjerager, Jon Ineson, all Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Bodil W. Lauridsen, GEUS and Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, 1350 Copenhagen K, Denmark.
Stefan Piasecki, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, 1350 Copenhagen K, Denmark.
Download PDF (10,00 Mb) TopA multi-disciplinary macrofossil study of late glacial to early Holocene sediments from Søndre Kobberdam, Hareskovene, Denmark
Bennike, O. & Mortensen, M.F. 2018. A multi-disciplinary macrofossil study of late glacial to early Holocene sediments from Søndre Kobberdam, Hareskovene, Denmark.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 113–122.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-05
Abstract:
During the early part of the Allerød period, from c. 13 600 to 13 330 years BP, unstable soils with a tundra-like open, treeless vegetation with Betula nana and Dryas octopetala were found around Søndre Kobberdam in Hareskovene. Open Betula pubescens woodland was not established until the middle Allerød about 13 330 years BP. During the Younger Dryas, Betula nana and Dryas octopetala spread again, and Betula pubescens almost disappeared. From the onset of the Holocene warming an open tundra landscape characterised the area. About 11 300 years BP Betula pubescens started to recolonise the region and Populus tremula and Pinus sylvetris arrived at c. 11 000 years BP, replacing the open landscape by woodland. Along the margin of the lake Carex paniculata, Carex riparia and Cladium mariscus were growing. The lake fauna included a rich and diverse fauna of molluscs that thrived in the carbonate-rich waters. We did not find any evidence for the local presence of Pinus sylvestris during the late glacial.
Keywords: Late glacial, vegetation history, fauna history, immigration history, Denmark.
Addresses:
Ole Bennike, Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Morten Fischer Mortensen, The National Museum of Denmark, I.C. Modewegs Vej, DK-2800 Kongens Lyngby, Denmark.
Corresponding author: Ole Bennike
Download PDF (1,68 Mb) TopStratigraphy and geothermal assessment of Mesozoic sandstone reservoirs in the Øresund Basin – exemplified by well data and seismic profiles
Erlström, M., Boldreel, L.O., Lindström, S., Kristensen, L., Mathiesen, A., Andersen, M.S., Kamla, E. & Nielsen, L.H. 2018. Stratigraphy and geothermal assessment of Mesozoic sandstone reservoirs in the Øresund Basin – exemplified by well data and seismic profiles.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 123–149.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-06
Abstract:
The Øresund Basin in the transnational area between Sweden and Denmark forms a marginal part of the Danish Basin. The structural outline and stratigraphy of the Mesozoic succession is described, and a novel interpretation and description of the subsurface geology and geothermal potential in the North Sjælland Half-graben is presented. The subsurface bedrock in the basin includes several Mesozoic intervals with potential geothermal sandstone reservoirs. Parts of the succession fulfill specific
geological requirements with regard to distribution, composition and quality of the sandstones. A characterisation of these is presently of great interest in the attempt to identify geothermal reservoirs suitable for district heating purposes. The results presented in this paper include for the first time a comprehensive description of the stratigraphic intervals as well as the characteristics of the potential Mesozoic geothermal reservoirs in the Øresund region, including their distribution, composition and physical properties. This is illustrated by seismic cross-sections and well sections. In addition, results from analyses and evaluations of porosity, permeability, formation fluids and temperature are presented. Six potential geothermal reservoirs in the Mesozoic succession are described and assessed. Primary focus is placed on the characteristics of the reservoirs in the Lower Triassic and Rhaetian–Lower Jurassic succession. The study shows that the Mesozoic reservoir sandstones vary considerably with respect to porosity and permeability. Values range between 5–25% for the pre-Rhaetian Triassic sandstones and are commonly >25% for the Rhaetian–Lower Jurassic and Lower Cretaceous sandstones. The corresponding permeability rarely reaches 500 mD for the pre-Rhaetian Triassic reservoirs, while it is commonly above one Darcy for the Rhaetian–Lower Jurassic and the Lower Cretaceous sandstones. The interpreted formation temperatures are 45–50°C at 1500 m, 60–70°C at 2000 m and 70–90°C at 2500 m depth. The combined results provide a geological framework for making site-specific predictions regarding appraisal of viable geothermal projects for district heating purposes in the region as well as reducing the risk of unsuccessful wells.
Keywords: Geothermal reservoirs, depth structure maps, formation fluids, porosity, permeability, temperature gradient, geothermal potential.
Addresses:
M. Erlström, Geological Survey of Sweden, Kiliansgatan 10, SE- 223 50 Lund, Sweden; also Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden.
L.O. Boldreel, Department of Geosciences and Natural Resource Management, Geology Section, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
S. Lindström, L. Kristensen, A. Mathiesen, M.S. Andersen, L.H. Nielsen, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
E. Kamla, GEO, Maglebjergvej 1, DK-2800 Kgs Lyngby, Denmark.
Interpretational challenges related to studies of chalk particle surfaces in scanning and transmission electron microscopy
Hjuler, M.L., Hansen, V.F. & Fabricius, I.L. 2018. Interpretational challenges related to studies of chalk particle surfaces in scanning and transmission electron microscopy.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 151–165.
ISSN 2245-7070. www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-07
Abstract
Scanning and transmission electron microscopy (SEM and TEM) are capable of characterising the morphology and structure of sub-micron size substances attached to chalk particle surfaces. Some characteristics, however, may originate from sample preparation or reflect interaction between sample and the electron beam. Misinterpretation of surface features may lead to wrong conclusions regarding grain surface properties and cementation level and thus to erroneous characterisation of hydrocarbon
reservoirs with respect to e.g. wettability, mechanical strength and maximum burial depth. In SEM, conductive coatings may mask surface details or generate artificial ornamentations, and carbon adhesive discs may cause the chalk surface to be covered with a thin carbon film. Electron beam acceleration voltage controls the degree of detail revealed by the electron beam, but in SEM a high electron beam acceleration voltage may provoke bending or curling of ultrathin particles. Recent organic filaments
may be confused with clay flakes, and authigenic non-carbonate minerals may have formed in the pore fluid and settled during fluid removal. In TEM, the high acceleration voltage may cause beam damage to calcite and transform the outermost atomic layers into Ca oxide. Thin graphite membranes observed by TEM may be contamination from the carbon film supporting the sample, and overlapping chalk particles in samples formed by drying of a suspension may give the impression of being cemented together. In TEM residual adhesive from the ion-milling process can be confused with cementation features.
Keywords: Scanning electron microscopy, transmission electron microscopy, chalk, surface coating, surface ornamentation, image interpretation.
Addresses:
Morten Leth Hjuler, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Vidar Folke Hansen, Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger, Norway.
Ida Lykke Fabricius, Department of Civil Engineering, Technical University of Denmark, Nordvej, Building 119, DK-2800 Kgs. Lyngby, Denmark.
Download PDF (9,45 Mb) TopBeach-ridge architecture constrained by beach topography and ground-penetrating radar, Itilleq (Laksebugt), south-west Disko, Greenland – implications for sea-level reconstructions.
Souza, P.E., Kroon, A. & Nielsen, L. 2018. Beach-ridge architecture constrained by beach topography and ground-penetrating radar, Itilleq (Laksebugt), south-west Disko, Greenland – implications for sea-level reconstructions.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 167–179.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-08
Abstract
Detailed topographic data and high-resolution ground-penetrating radar (GPR) reflection data are presented from the present-day beach and across successive raised beach ridges at Itilleq, south-west Disko, West Greenland. In the western part of the study area, the present low-tide level is well defined by an abrupt change in sediment grain size between the sandy foreshore and the upper shoreface that is characterised by frequently occurring large clasts. The main parts of both fine and large clasts appear to be locally derived. Seaward-dipping reflections form downlap points, which are clearly identified in all beach-ridge GPR profiles. Most of them are located at the boundary between a unit with reflection characteristics representing palaeo-foreshore deposits and a deeper and more complex radar unit characterised by diffractions; the deeper unit is not penetrated to large depths by the GPR signals. Based on observations of the active shoreface regime, large clasts are interpreted to give rise to scattering observed near the top of the deeper radar unit. We regard the downlap points located at this radar boundary as markers of palaeo-low-tide levels. In some places, scattering hyperbolas are more pronounced and frequent than in others, suggesting differences in the occurrence of large boulders.
Keywords: Downlap points, sea level, berm evolution, beach ridges, Arctic coasts.
Addresses:
Priscila E. Souza, Aart Kroon, Lars Nielsen, Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
Corresponding author: Priscila E. Souza.
Download PDF (3,09 Mb) TopA crocodilian coprolite from the lower Oligocene Viborg Formation of Sofienlund Lergrav, Denmark
Milàn, J., Rasmussen, E.S. & Dybkjær, K. 2018. A crocodilian coprolite from the lower Oligocene Viborg Formation of Sofienlund Lergrav, Denmark.
© 2018 by Bulletin of the Geological Society of Denmark, vol. 66, pp. 181–187.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-09
Abstract
A large, well-preserved vertebrate coprolite found in the clay pit Sofienlund Lergrav, Jylland, is identified as crocodilian due to its size and morphology. The coprolite consists of several concentric layers wrapped around a more homogeneous core. Weak constriction marks are present on the surface. Dinoflagellate cyst contents of the coprolite indicate a mid-Lutetian to earliest Rupelian (middle Eocene to earliest Oligocene) age, which at Sofienlund Lergrav places it within the lower Oligocene Viborg Formation. The coprolite can thus be dated as approximately 33–34 Ma old. The Viborg Formation in Denmark represents a period with deposition of hemipelagic marine clay and formation of glaucony.
The nearest shoreline was located c. 200 km north of the location of the present day Sofienlund Lergrav, and the climate was humid, warm-temperate to sub-tropical. The presence of a crocodilian coprolite is an important addition to the sparse Oligocene vertebrate fauna of Denmark, which previously only consisted of sharks and cetaceans.
Keywords: Coprolite, Palaeogene, Oligocene, vertebrate fauna, Denmark, Crocodilian.
Addresses:
Jesper Milàn, Geomuseum Faxe, Østsjællands Museum, Østervej 2, DK-4640 Faxe, Denmark; also Natural History Museum of Denmark, Øster Voldgade 5-7, DK-1465 Copenhagen K, Denmark.
Erik Skovbjerg Rasmussen and Karen Dybkjær, Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Corresponding author: Jesper Milàn.
Download PDF (1,14 Mb) TopMeandering river deposits in sediment cores, the Middle Jurassic Alma Field, Southern Danish Central Graben
Glad, A.C., Willumsen, M.E., Boldreel, L. O. & Clemmensen, L.B., 2018. Meandering river deposits in sediment cores, the Middle Jurassic Alma Field, Southern Danish Central Graben.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 189–209.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-10
Abstract
Fluvial deposits are amongst the most important terrestrial hydrocarbon reservoirs, but the complex nature of these deposits is challenging in subsurface reservoir characterisation. This study is the first detailed facies analysis of the meandering river deposits of the Middle Jurassic Alma Field situated in the southern Danish North Sea. The fluvial sandstones and their associated deposits are described and interpreted based on studies from two core sites (Alma-1X and Alma-2X). The facies analysis of the cores demonstrates the presence of three meandering river facies associations: Channel deposits, channel margin deposits and floodplain deposits. The channel deposits comprise channel thalweg and point bar sediments, the channel margin deposits include crevasse channel and crevasse splay sediments, while the floodplain deposits comprise overbank and backswamp sediments. The point bar deposits are composed of fine- to medium-grained sandstones but can contain intervals of finer grained sediments, particularly in their upper parts where they can grade into muddy sandstones or true heterolithic deposits. Preserved sand body thicknesses (channel thalweg and point bar deposits) in both Alma cores have a mean value of 2.6 m and a maximum value of 4.35 m (Alma-1X) and 6.55 m (Alma-2X). Using maximum values of channel deposit thicknesses, and assuming the preservation conditions are met, the width of the largest ancient channel belt in Alma-1X would be between 90 m and 200 m or around 900 m, depending on whether the fluvial system is mud-rich or sand-rich. The same method applied to Alma-2X gives a width of the largest channel belt between 130 m and 330 m or around 1300 m.
Fluvial sediments of the Middle Jurassic Scalby Formation (north-east England) were deposited in a sandy meandering river with sedimentary characteristics corresponding to those observed in the Alma cores. Outcrop analogue investigations of this formation were carried out to examine the architecture of the fluvial facies in a two-dimensional section with emphasis on channel thalweg and point bar deposits.
Combined evidence from core analysis and outcrop analogue studies suggests that the fluvial deposits in the Alma Field represent a mixed-load meandering river system with sandy point bars. The meandering river system developed on a coastal plain with overbank fines and organic-rich backswamp deposits. The mud-rich or heterolithic deposits in the upper part of the point bar facies intervals are noteworthy and could indicate markedly fluctuating discharge in a mixed-load river.
Keywords: Meandering river deposits, Middle Jurassic, Alma Field, core studies, facies analysis, analogue outcrop study, fluvial reservoirs.
Addresses:
Aslaug C. Glad [presently also Acglad [at] dtu [dot] dk], Lars Ole Boldreel and Lars B. Clemmensen, Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark. Mads E. Willumsen, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Corresponding author: Aslaug C. Glad.
Download PDF (3,41 Mb) TopTwo new finds of turtle remains from the Danian and Selandian (Paleocene) deposits of Denmark with evidence of predation by crocodilians and sharks
Myrvold, K.S., Milàn, J. & Rasmussen, J.A. 2018. Two new finds of turtle remains from the Danian and Selandian (Paleocene) deposits of Denmark with evidence of predation by crocodilians and sharks.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 211–218.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-11
Abstract
Two new fragments of a turtle carapace and a turtle plastron (hypoplastron) have been recovered from glacially transported boulders of Danian and Selandian age. The hypoplastron is identified as Ctenochelys cf. stenoporus, while the carapace fragment can only be assigned to the family Cheloniidae indet. Both specimens show evidence of predation by crocodilians in the form of rows of circular pits in the bones, and one specimen has rows of elongated scrape traces interpreted as scavenging by sharks. Together with the other, rare finds from the middle Danian of the Faxe Quarry and from late Danian deposits in the Copenhagen area, these new finds add important new knowledge to the sparse fossil record of turtles in Scandinavia, as well as evidence that the genus Ctenochelys survived across the K/Pg Boundary.
Addresses:
Kristine Steigardotter Myrvold, Natural History Museum of Denmark, Øster Voldgade 5–7, DK-1350 Copenhagen K. Denmark.
Jesper Milàn, Geomuseum Faxe/Østsjællands Museum, Østervej 2, DK-4640 Faxe, Denmark; also Natural History Museum of Denmark, Øster Voldgade 5–7, DK-1350 Copenhagen K. Denmark.
Jan Audun Rasmussen, Fossil and Moclay Museum/Museum Mors, Skarrehagevej 8, DK-7900 Nykøbing Mors, Denmark.
Corresponding author: Jesper Milàn.
Download PDF (1,71 Mb) TopBook Review: Fischer, A. & Pedersen, L. (eds) 2018: Oceans of Archaeology.
Bennike, O. 26-10-2018. Book review of Fischer, A. & Pedersen, L. (eds) 2018: Oceans of Archaeology. Jysk Arkæologisk Selskabs Skrifter vol. 101, 237 pp. ISBN 978-87-93423-18-3. Aarhus: Aarhus Universitetsforlag.
©2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 219–221.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-12
Addresses:
Ole Bennike, Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Download PDF (1001,73 Kb) TopAnopolenus henrici Salter, a middle Cambrian (Drumian) centropleurid trilobite from the Alum Shale Formation of Scandinavia
Weidner, T. & Ebbestad, J.O.R. 06-11-2018. Anopolenus henrici Salter, a middle Cambrian (Drumian) centropleurid trilobite from the Alum Shale Formation of Scandinavia.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 223–228.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-13
Abstract
Centropleurid trilobites include five genera of which Centropleura Angelin, Anopolenus Salter, Clarella Howell and Luhops Šnajdr are known from eight species in the traditional middle Cambrian (Miaolingian Series, Drumian Stage) of Sweden and Denmark (Bornholm). Beishanella Xiang & Zhang has not been recorded in Scandinavia so far, and no centropleurids have been reported from Norway. Of these taxa, only Centropleura is common in Scandinavia. Two pygidia previously identified as Centropleura sp. and Anopolenus sp. from erratics in Germany and Bornholm, respectively, as well as a new pygidum from Scania in Sweden are here identified as Anopolenus henrici Salter. Elsewhere, the species is known from Wales, Avalonian Canada, Siberia, Alaska, and Sardinia, occurring in the A. atavus and P. punctuosus zones (the former in Siberia only). The presence of this species increases the known diversity of Centropleuridae in Scandinavia and is important for correlation between Baltica and Avalonia.
Keywords: Centropleurid trilobite, Miaolingian, Drumian, Alum Shale Formation, Bornholm, Scania, Scandinavia.
Addresses:
Thomas Weidner, Ravnholtvej 23, Rårup, DK-7130 Juelsminde, Denmark.
Jan Ove R. Ebbestad, Museum of Evolution, Uppsala University, Norbyvägen 22, SE-752 36 Uppsala, Sweden.
Corresponding author: Jan Ove R. Ebbestad.
Download PDF (1,36 Mb) TopFirst record of Epicymatoceras vaelsense (Nautilida) from the Maastrichtian white chalk of northern Denmark
Malchyk, O. & Machalski, M. 2018. First record of Epicymatoceras vaelsense (Nautilida) from the Maastrichtian white chalk of northern Denmark.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 229–235.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-14
Abstract
The atypical Late Cretaceous nautilid Epicymatoceras vaelsense (Binkhorst van den Binkhorst, 1862) is described and illustrated on the basis of three specimens from the Maastrichtian white chalk of Denmark. One of these is probably from the lower/upper Maastrichtian boundary interval at Frejlev, while the other two originate from the uppermost Maastrichtian chalk as exposed in the Dania quarry; both localities are in Jylland, northern Denmark. These are first reports of E. vaelsense from Denmark; the species has previously been recorded from the uppermost Campanian and lower Maastrichtian of the Netherlands, Belgium, northern Germany and Poland. The presence of E. vaelsense in the topmost Maastrichtian white chalk in the Dania quarry is considered the youngest record of Epicymatoceras known to date, suggesting the persistence of the genus until the end of the Cretaceous. The diameter of the embryonic conch of the Danish E. vaelsense may be estimated at c. 30 mm, based on an individual from the Dania quarry, confirming earlier observations that the species possessed one of the largest embryonic conchs amongst Late Cretaceous nautilids.
Keywords: Upper Cretaceous, Cephalopoda, Epicymatoceras, Denmark, embryonic conch, K–Pg mass extinction.
Addresses
Oksana Malchyk, Marcin Machalski, Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warszawa, Poland.
Download PDF (1,43 Mb) TopGamma-ray log correlation and stratigraphic architecture of the Cambro-Ordovician Alum Shale Formation on Bornholm, Denmark: Evidence for differential syndepositional isostasy
Nielsen, A.T., Schovsbo, N.H., Klitten, K., Woollhead, D. & Rasmussen, C.M.Ø. 2018. Gamma-ray log correlation and stratigraphic architecture of the Cambro-Ordovician Alum Shale Formation on Bornholm, Denmark: Evidence for differential syndepositional isostasy.
© 2018 by Bulletin of the Geological Society of Denmark, Vol. 66, pp. 237–273.
ISSN 2245-7070. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2018-66-15
Abstract
The Cambro–Ordovician Alum Shale Formation on Bornholm, Denmark, is in total 26.7 to ≥ 34.9 m thick in nine boreholes, but may be up to ~39 m thick. The well sections are correlated using gamma-ray logs supplemented in some boreholes with resistivity and sonic logs. The gamma radiation of the ‘hot’ Alum Shale Formation primarily reflects the uranium content, which is moderately high in the Miaolingian (≈ middle Cambrian) and Tremadocian (Lower Ordovician), and very high in the Furongian (≈ upper Cambrian). The log pattern is calibrated with the detailed biozonation established in the Gislövshammar-1 and -2 wells in south-eastern Skåne, Sweden. Except for the Eccaparadoxides oelandicus Superzone, all superzones known from the Alum Shale in Scandinavia are also developed on Bornholm, but not all zones.
On Bornholm, the Miaolingian interval is 7.2–11.9 m thick, the Furongian is 16.4–22.8 m thick and the Tremadocian is 2.5–4.0 m thick. The Miaolingian strata exhibit no systematic thickness variations across southern Bornholm, whereas the Furongian Parabolina, Peltura and Acerocarina Superzones and, less pronounced, the Tremadocian, show increased condensation towards the south-east. In comparison with Skåne, the Alum Shale Formation is overall strongly condensed on Bornholm, but different stratigraphic levels show variable developments. The Miaolingian Paradoxides paradoxissimus Superzone is thus extremely condensed and incomplete, whereas the Paradoxides forchhammeri Superzone has almost the same thickness as in Skåne, and locally is even thicker. The Furongian Olenus and Parabolina Superzones are slightly thinner than in Skåne while the Protopeltura, Peltura and Acerocarina Superzones are half as thick or less. The Tremadocian is also much thinner on Bornholm. The Furongian Olenus scanicus–O. rotundatus and Parabolina brevispina Zones seem to be developed on Bornholm, and a thin ‘Leptoplastus neglectus’ Zone is also possibly present. The ‘Parabolina megalops’ Zone in the upper part of the Peltura Superzone appears to be absent. It is impossible to distinguish the individual thin zones in the lower part of the Acerocarina Superzone using wireline logs. A thin veneer of the Lower Ordovician Tøyen Formation, hitherto considered absent on Bornholm, is described from the Billegrav-2 core. It may also be present in the uncored Sømarken-3 and -4 wells. The Middle Ordovician Komstad Limestone Formation thins from c. 4.0–4.7 m in the Læså area to 0.1– c. 2.5 m in the Øleå area.
The general decrease in thickness of Cambro–Ordovician strata from Skåne to Bornholm and also within Bornholm from the Læså to the Øleå area is inferred to reflect isostatic uplift of the southern margin of Baltica commencing with the terminal 'early' Cambrian Hawke Bay Event and lasting until the Late Ordovician. In detail, several uplift and subsidence phases can be discerned. The isostatic adjustments are surmised to reflect stress changes related to ongoing plate tectonic processes in the adjacent closing Tornquist Sea.
Keywords: Cambrian, Ordovician, Alum Shale Formation, wireline log correlation, uranium, biostratigraphy, isostasy, Scandinavia, Bornholm.
Addresses
Arne Thorshøj Nielsen, Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Niels Hemmingsen Schovsbo, Kurt Klitten, Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
David Woollhead, Toftegårds Allé 7, lejl. 2a, DK-2500 Valby, Denmark.
Christian Mac Ørum Rasmussen, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, DK-1350 Copenhagen K, Denmark.
Corresponding author: Arne Thorshøj Nielsen.
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