Publikationer

A 7000-year record of coastal evolution, Vejers, SW Jutland, Denmark

Clemmensen, L.B., Pedersen, K., Murray, A. & Heinemeier, J. 2006–09–14. 2006–09–14. A 7000-year
of coastal evolution, Vejers, SW Jutland, Denmark.Bulletin of the Geological Society of Denmark, Vol. 53, pp. 1–22. (www.2dgf.dk/publikationer/bulletin)
https://doi.org/10.37570/bgsd-2006-53-01

Abstract: The Holocene coastal lowland at Vejers in western Jutland has formed during the last 7000 years. The lowland is composed of a large, NNE-SSW trending spit system associated with minor and only locally developed strandplain or beach ridge systems. The main spit and back-barrier system is bounded to the north and east (inland) by old moraine landscapes (Varde Bakkeø). Most of the coastal system and also large parts of the adjacent moraine landscape is covered by aeolian sand.

In this study one of the minor strandplain systems is investigated. This system is developed at the south-western margin of the old moraine landscape at Grovsø, a lake near Vejers. The Holocene sedimentary evolution of this latter system is evaluated on the basis of data from two closely situated cores and Ground-Penetrating Radar (GPR) mapping. Both cores consist of a lowermost unit with marine sediment, a middle unit with lake-aeolian sand and an uppermost unit with aeolian sandplain deposits. Peat layers and peat-rich paleosols are common. These peat-rich horizons are dated by the Accelerator Mass Spectrometry (AMS) radiocarbon technique, while the intervening sand layers are dated by Optically Stimulated Luminescence (OSL). Combined evidence from the sedimentological and chronological studies of the cores and the GPR survey, indicate that the area was first transgressed at about 5100 BC. During the subsequent period (5100–2700 BC) relative sea level rose about 5 meters, the strandplain prograded, and small coastal dunes formed. During this progradational event a large strandplain lake formed behind the frontal dune ridge and this lake was filled primarily by aeolian sand. Aeolian sand drift may have been most intense around 3000 BC. This first period of large-scale aeolian activity ended some time before 2300 BC with formation of a peat-rich paleosol.

Aeolian activity, however, was soon re-established and resulted in the formation of a large sandplain with small dunes. Aeolian sand movement and accumulation, however, was punctuated by periods of landscape stabilisation and peat-rich paleosol formation. Changes from landscape stabilisation to dune field activity took place at about 2300 BC, 1450 BC, 800 BC, and 650 BC. Aeolian accumulation at the study site terminated at about AD 0, but other evidence indicates renewed aeolian activity in the dune field after AD 300 and between AD 1100 and 1900. The chronology of some of these aeolian activity phases are synchronous with cooling events in the North Atlantic region suggesting that climatic change strongly influenced dune field dynamics.

Keywords: Holocene, coastal evolution, aeolian, climate change

Addresses:
Lars B. Clemmensen [ larsc [at] geol [dot] ku [dot] dk ], Geological Institute, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Karsten Pedersen [kap [at] asiaq [dot] gl], Geological Institute, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Andrew Murray [andrew [dot] murray [at] risoe [dot] dk], Nordic Laboratory for Luminescence Dating, Department of Earth Sciences, University of Aarhus, Risø National Laboratory DK-4000 Roskilde, Denmark.
Jan Heinemeier [jh [at] phys [dot] au [dot] dk], AMS 14C Dating Laboratory, Institute of Physics and Astronomy, University of Aarhus, DK-8000 Århus C, Denmark
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Neogene fluvial and nearshore marine deposits of the Salten section, central Jylland, Denmark

Rasmussen, E.S., Dybkjær, K. & Piasecki, S. 2006–04–10. Neogene fluvial and nearshore marine deposits of the Salten section, central Jylland, Denmark. Bulletin of the Geological Society of Denmark, Vol. 53, pp. 23–37. © 2006 by Geological Society of Denmark.
(www.2dgf.dk/ publikationer/bulletin).
https://doi.org/10.37570/bgsd-2006-53-02

Abstract: The deposits of the Salten succession was laid down in a transgressive-regressive event during the latest Chattian (latest Oligocene) and/or the early Aquitanian (earliest Miocene). Five facies associations are recognised and interpretated as deposited in 1: High-energy fluvial, 2: Low-energy fluvial, 3: Flood plain, 4: Tidally influenced fluvial, and 5: Marginal marine/delta plain environments.
The dating by biostratigraphy indicates that the Salten succession correlates with the Vejle
Fjord Formation. The succession correlates with fluvial deposits outcropping in gravel pits at Addit and Voervadsbro and thus these deposits are of latest Oligocene – earliest Miocene. This is in contrast to former studies that indicate a correlation with the upper Lower – Middle Miocene Odderup Formation. The age of the Salten succession as revealed from this study indicates that the Miocene deposits in Jylland are progressively truncated towards the north and east.

Keywords: Sedimentary facies, stratigraphy, dinoflagellate cysts, Denmark, Miocene.

Addresses:
Erik S. Rasmussen [ esr [at] geus [dot] dk ] , Karen Dybkjær & Stefan Piasecki. Geological Survey of Denmark and Greenland, Geocenter Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K.

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Vertebrate micro-remains from the Upper Devonian of East Greenland with comments on the Frasnian–Famennian boundary

Blom, H., Carlsson, A. & Marshall, J.E.A. 2006–11–09. Vertebrate micro-remains from the Upper Devonian of East Greenland with comments on the Frasnian–Famennian boundary. Bulletin of the Geological Society of Denmark. Vol. 53, pp. 87–93. © 2006 by Geological Society of Denmark. ISSN 0011–0297.
(www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2006-53-03

Abstract: Vertebrate micro-remains of jawless vertebrates (psammosteid heterostracans) and gnathostomes (acanthodians and sarcopterygians) occur in a residue collected from the Late Devonian Kap Graah Group sandstones of East Greenland. Fragmentary and isolated elements of psammosteids are assigned to Psammosteus sp. The acanthodians are represented by scales of acanthodiform type and poorly preserved fin spines. Tooth and scale fragments of sarcopterygians may suggest a porolepiform affinity. This assemblage and the associated macro-vertebrate fauna indicate a Frasnian age for anotherwise assumed Famennian part of the East Greenland succession, and do rather effectively bracket the Frasnian–Famennian boundary.

Keywords: Upper Devonian, East Greenland, Kap Graah Group, jawless vertebrates, psammosteids,acanthodians, sarcopterygians.
Addresses:
Henning Blom [ henning [dot] blom [at] ebc [dot] uu [dot] se ] & Anders Carlsson, Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology, Norbyvägen 18A, SE-752 36 Uppsala, Sweden.
John E. A. Marshall, School of Ocean and Earth Science, University of Southampton, NationalOceanography Centre Southampton, European Way, Southampton, SO14 3ZH, UK.
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Cambrian to basal Ordovician lithostratigraphy in southern Scandinavia

Nielsen, A.T. & Schovsbo, N.H. 2007–11–06. Cambrian to basal Ordovician lithostratigraphy in southern Scandinavia. Bulletin of the Geological Society of Denmark, Vol. 53, pp. 47–92. © 2007 by Geological Society of Denmark. ISSN 0011–6297.
(www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2006-53-04

Abstract: The lithostratigraphic subdivision of the Cambrian successions in Scania-Bornholm, Östergötland, Västergötland, Närke, Öland-Gotland, the southern Bothnian Sea and the Mjøsa District is reviewed and revised.

The review includes the Tremadocian part of the Alum Shale Formation. The Cambrian of Scania-Bornholmcomprises the Nexø, Hardeberga, Læså, Gislöv and Alum Shale formations. The Nexø Formation of Bornholm is subdivided into the new Gadeby and Langeskanse members, which are c. 40 and 50 m thick, respectively.

The 1–15 m thick arkosic basal part of the sandstone succession in Scania, previously treated as part of the Hardeberga Sandstone, is allocated to the Nexø Formation. The ‘Balka Sandstone’ of Bornholm is considered an integrated part of the Hardeberga Formation and the designation Balka Sandstone Formation is abandoned. The Haddeberga Formation, which is 109 m thick on Bornholm and c. 105–110 m in Scania, comprises the Hadeborg (new), Lunkaberg (Scania only), Vik, Brantevik and Tobisvik members. The overlying Læså Formation contains the Norretorp and Rispebjerg members; the former is regarded a senior synonym of the Broens Odde member of Bornholm. The Norretorp Member is thicker in Scania than previously estimated (> 25 m, rather likely even > 30 m); on Bornholm it is 103 m thick. The Rispebjerg Member is 1–3.7 m thick.

The Cambrian of the Öland-Gotland area, the southern Bothnian Sea and the districts of south central Sweden comprises the File Haidar, Borgholm and Alum Shale formations. The File Haidar Formation of the Öland-Gotland area, which is up to 127 m thick, includes the Viklau, När Shale and När Sandstone members; the Grötlingbo Member is transferred to the Borgholm Formation. The validity of the Kalmarsund Member is questioned; its lithological characteristics probably reflect diagenesis. The Lingulid and Mickwitzia sandstone members constitute the File Haidar Formation in south central Sweden, where the unit is up to 37 m thick. New names and to some extent new definitions are introduced for the members of the Borgholm Formation, viz. Kvarntorp Member (new name for the thin glauconitic sandstone overlying the Lingulid Sandstone Member in central Sweden), Mossberga Member (new name for the coarse part of the Eccaparadoxides oelandicus Shale sensu Hagenfeldt 1994), Bårstad Member (new name for the fine-grained part of the Eccaparadoxides oelandicus Shale), Äleklinta Member (new name for theParadoxides paradoxissimus Siltstone) and Tornby Member (new name for the Paradoxides paradoxissimus Shale). The Granulata Conglomerate (= Acrothele Conglomerate of previous literature) is formally ranked as a bed at the base of the Äleklinta Member. The informal designation Söderfjärden formation is abandoned. The Borgholm Formation locally exceeds 150 m in the Öland-Gotland area; it is significantly thinner in south central Sweden.

The Cambrian of the Mjøsa District comprises the Vangsås, Ringstrand and Alum Shale formations. Of these, the new Ringstrand Formation encompasses the strata between the Vangsås and Alum Shale formations, previously referred to as the ‘Holmia Series’. The Ringstrand Formation includes the Brennsætersag (new), Redalen (new), Tømten (new), Evjevik and Skyberg (new) members. Thickness estimates are rendered difficult due to tectonic overprinting, but the Ringstrand Formation is probably about 50-60 m thick in the Lower Allochthon around Lake Mjøsa.

The Scandinavian Alum Shale Formation, which is up to 100 m thick in Scania and even thicker subsurface of Kattegat, is restricted to encompass only kerogeneous mudstones/shales with subordinate limestones and very rare sandstone beds. It is proposed abandoning the Kläppe Shale and Fjällbränna Formation of the Lower Allochthon of Jämtland and to regard these units as part of the Alum Shale Formation. Several widespread thin units are formally ranked as beds within the Alum Shale Formation, including the Forsemölla Limestone Bed (new name for the ‘fragment limestone’at or near the base of the Alum Shale Formation in Scania; this unit is also developed in Östergötland and Närke), the Exsulans Limestone Bed, the Hyolithes Limestone Bed, the Andrarum Limestone Bed, the Exporrecta Conglomerate Bed, the Kakeled Limestone Bed (new name for the ‘Great Orsten Bank’ of south central Sweden), the Skåningstorp Sandstone Bed (new name for the thin sandstoneintercalation at the base of the Ordovician in Östergötland) and the Incipiens Limestone Bed.

Keywords: Cambrian, Tremadocian, lithostratigraphy, Denmark, Sweden, Norway.

Addresses:
Arne Thorshøj Nielsen [ arnet [at] snm [dot] ku [dot] dk ], Geological Museum, University of Copenhagen, Øster Voldgade5–7, DK-1350 København K, Denmark.
Niels Schovsbo, Geological Survey of Denmark and Greenland, [nsc [at] geus [dot] dk] Øster Voldgade 10, DK-1350 København K, Denmark.
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Fluviokarst in the top of the Maastrichtian chalk at Rørdal, Northern Jutland, Denmark

Stenestad, E. 2006–11–30. Fluviokarst in the top of the Maastrichtian chalk at Rørdal, Northern Jutland, Denmark. Bulletin of the Geological Society of Denmark, Vol. 53, pp. 93–110. © 2006 by Geological Society of Denmark. ISSN 0011–6297.
(www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2006-53-05

Abstract: Construction work and planning operations in the second half of the 20th century in northern Jutland supplied important detail to the geological background for the topographic development of the Rørdal area, eastern Aalborg.

The inversion and uplift of the Sorgenfrei-Tornquist Zone in end-Cretaceous – Paleocene time initiated some 60 million years of erosion that removed the uppermost Cretaceous and Cenozoic deposits. Detailed mapping of the pre-Pleistocene chalk surface supplemented with aerial photographs, quarry sections and excavated sections document the existence of karst phenomena and demonstrate that fluviokarst processes played an important role in formation of the topography.

Live and palaeokarst features are supposed to be widespread in Danish limestone areas and the possible existence in a given area may be important in relation to areal planning, including raw materials extraction and water supply and protection.

Keywords: Fluviokarst, sinkhole, doline, buried valley, crop mark, pre-Pleistocene surface, groundwater pollution, Maastrichtian chalk.

Addresses:
Erik Stenestad [ estenestad [at] hotmail [dot] com ] Højbjerg Vang 23, DK-2840 Holte.

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Early Silurian brachiopods (Rhynchonellata) from the Sælabonn Formation of the Ringerike district, Norway

Thomsen, E., Jin, J. & Harper, D.A.T. 2006–12–11. Early Silurian brachiopods (Rhynchonellata) from the Sælabonn Formation of the Ringerike district, Norway. Bulletin of the Geological Society of Denmark, Vol. 53, pp. 111–126. © 2006 by Geological Society of Denmark. ISSN 0011–6297. (www.2dgf.dk/publikationer/bulletin).
https://doi.org/10.37570/bgsd-2006-53-06

Abstract: A revision of Kiær’s index fossils of “Etage” 6 in the Ringerike district of Norway reveals the presence of four species: Rostricellula wadti sp. nov., Platytrochalos ringerikensis sp. nov., Platytrochalos rabbei sp. nov., and Zygospiraella duboisi.

Rostricellula is a common Ordovician rhynchonellide brachiopod and is known to occur in the Lower Silurian as a holdover taxon in only a few localities worldwide. Previously, Platytrochalos was known only from the Lower Silurian (Llandoverian) rocks of Anticosti Island, eastern Canada.

The occurrence of this rare genus in the Ringerike district provides additional information for the early evolution and palaeogeography of the taxonomically enigmatic family Leptocoeliidae. Zygospiraella is regarded as an index genus for the Rhuddanian, and the presence of Z. duboisi provides a useful biostratigraphic control on the age of the Sælabonn Formation.

Keywords: Rhynchonellate brachiopods, Early Silurian, biostratigraphy, taxonomy, Norway.

Addresses:
Thomsen, E. [ elsebeth [dot] thomsen [at] tmu [dot] uit [dot] no ], Department of Geology, Tromsø University Museum, NO- 9037 Tromsø, Norway;
Jin, J. [jjin [at] uwo [dot] ca], Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada;
Harper, D.A.T. [dharper [at] snm [dot] ku [dot] dk], Geologisk Museum, Øster Voldgade 5-7, DK-1350 København K, Denmark.

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