Contents of issue 1
Surlyk, F.: Walter Kegel Christensen 25. maj 1942 – 18. oktober 2002.
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https://doi.org/10.37570/bgsd-2003-50-16
Harper, D. & Stouge, S: Preface
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https://doi.org/10.37570/bgsd-2003-50-17
Hammer, Ø :
A database of fossil occurrences in the Ordovician of Baltoscandia
Schovsbo, N.H. :
The geochemistry of Lower Palaeozoic sediments deposited on the margins of Baltica..
Hints, L. & Harper, D.A.T. :
Review of the Ordovician rhynchonelliformean Brachiopoda of the East Baltic: Their distribution and biofacies.
Erratum: Article by O.V.Vejbæk in vol. 49 (2).
Hansen, J. & Harper, D.A.T. :
Brachiopod macrofaunal distribution through the upper Volkhov – lower Kunda (Lower Ordovician) rocks, Lynna River, St. Petersburg region.
Vinn, O. & Harper, D.A.T. :
Diversification patterns in the clitambonitoid brachiopods of the Ordovician of Baltoscandia..
Tolmacheva T., Fedorov P. & Egerquist E .:
Conodonts and brachiopods from the Volkhov Stage (Lower Ordovician) microbial mud mound at Putilovo Quarry, north-western Russia
Stouge, S. & Nielsen, Arne T. :
An integrated biostratigraphical analysis of the Volkhov–Kunda (Lower Ordovician) succession at Fågelsång, Scania, Sweden..
Bergström, J., Zhou Zhi-Qiang, Zhou Zhi-yi & Yuan Wen-Wei :
The Asaphus raniceps problem in the Ordovician of Sweden..
Hansen, T. & Nielsen, A.T. :
Upper Arenig trilobite biostratigraphy and sea-level changes at Lynna River near Volkhov, Russia..
Hints, O., Hints, L., Meidla, T. & Sohar, K. :
Biotic effects of the Ordovician Kinnekulle ash-fall recorded in northern Estonia..
Federov, P. :
Lower Ordovician mud mounds from the St. Petersburg region, northwestern Russia..
Contents of issue 2
Hede, S.U.:
Prehistoric settlements and Holocene relative sea-level changes in northwest Sjælland, Denmark.
Elected as DGF Paper of the Year 2003
Korsager, B., Bennike, O. & Houmark-Nielsen, M.:
Salix polaris leaves dated at 14.3 ka BP from northern Jylland, Denmark..
Hansen, J. & Hansen, T.:
Stratigraphy and sea-level fluctuations in the Upper Miocene Gram Formation, south-western Denmark.
Weibel, R.:
Alteration of detrital Fe-Ti oxides in Miocene fluvial deposits, central Jutland, Denmark.
Bromley, R.G. & Uchman, A.:
Trace fossils from the Lower and Middle Jurassic marginal marine deposits of the Sorthat Formation, Bornholm, Denmark..
A database of fossil occurrences in the Ordovician of Baltoscandia
Hammer, Ø. 2003–04–30: A database of fossil occurrences in the Ordovician of Baltoscandia. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 5–9. Copenhagen. © 2003 by Geological Society of Denmark. ISSN 0011–6297.
https://doi.org/10.37570/bgsd-2003-50-18
A database recording published fossil occurrences in the Ordovician of Baltoscandia has been constructed and made available on the Internet (http://asaphus.uio.no). The database presently contains10340 entries, each recording the first and last appearances of a single species at a single locality, together with other stratigraphical, taxonomic and geographical information. The data are
taken from 141 publications, most of them from 1980 or later but also included are some older key references. The database will be continuously maintained, revised and expanded. In addition to serving as a reference for researchers working on the Ordovician of Baltoscandia, the database hasbeen used to produce biodiversity curves for different fossil groups. These curves reflect the global increase in biodiversity through the Ordovician, but also show interesting local fluctuations.
Keywords: Ordovician, Baltoscandia, Baltica, database, diversity
Addresses:
Øyvind Hammer [ ohammer [at] nhm [dot] uio [dot] no ], Geological Museum, Boks 1172 Blindern, N-0318 Oslo, Norway. 15 June 2001.
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The geochemistry of Lower Palaeozoic sediments deposited on the margins of Baltica
Schovsbo, N.H. 2003–04–30: The geochemistry of Lower Palaeozoic sediments deposited on the margins of Baltica. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 11–27, Copenhagen. © 2003 by Geological Society of Denmark.
https://doi.org/10.37570/bgsd-2003-50-01
Abstract: A regional survey of the geochemical composition of Lower Palaeozoic shales deposited on Baltica indicates that Llanvirn (Lower/Middle Ordovician) to Lower Silurian shales have higher concentrations of Na, Mg, Cr, Ni and Fe and lower concentrations of K, Rb and Ti compared to Arenig shales. This geochemical signature can be traced from Scania to the Oslo Region, i.e. in areas approximately 500 km apart, but is not present in Middle Ordovician sediments from Avalonia. The geochemical signature matches island arc tholeiites such as those in the Fundsjø Group within the Upper Allochthon of the Norwegian-Swedish Caledonides. Hence, these sediments were probably predominantly derived from island arcs formed during the end phase of closure of the Iapetus Ocean. Simple two component mixing calculations between oceanic and continental sediment sources suggest that the oceanic component diminishes towards the south where modifications related to longer sediment transport distances can be recognised. The introduction of sediment derived from island arcs coincides with increases in subsidence rates in the Oslo Region and may reflect an early stage in foreland basin development. The presence of the geochemical signature in Scania implies that island arcs systems were geographically widespread. The combined evidence indicates that the Arenig/Llanvirn boundary marks an important change in the continuing closure of the Iapetus Ocean. The data suggest that island arcs were obducted onto the outer margins of Baltica presumably during the Arenig. Continued obduction of island arcs in the Mid Ordovician and younger intervals is likely.
Keywords: Provenance, Caledonides, Scania, Oslo, Lower Palaeozoic.
Addresses:
Niels H. Schovsbo [ nielss [at] savik [dot] geomus [dot] ku [dot] dk ], Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. 28 August 2001.
Review of the Ordovician rhynchonelliformean Brachiopoda of the East Baltic: their distribution and biofacies
Hints, L. & Harper, D.A.T. 2003–04–30: Review of the Ordovician rhynchonelliformean Brachiopoda of the East Baltic: Their distribution and biofacies. Bulletin of the Geological Society of Denmark, vol. 50, pp. 29–43, Copenhagen. © 2003 by Geological Society of Denmark.
https://doi.org/10.37570/bgsd-2003-50-02
Abstract: Analyses of the distribution, in time and space, of approximately 300 Ordovician rhynchonelliformean brachiopods in the East Baltic allow the development of a faunal template for the Baltic Province (sensu stricto) within the context of the European Realm. Two different brachiopod magnafacies, the upper and lower ramp associations, are monitored through time. Changes in the brachiopod fauna through uppermost Hunneberg to the Porkuni stages are demonstrated from different drill core sections and some bedrock exposures located in facially contrasting areas across the region. The main developmental trends within the brachiopod biofacies of the shallower part of the palaeobasin (North Estonian facies belt) are characterized by relatively continuous changes in taxonomic composition including the evolution of endemics and the establishment of relatively persistent associations, especially during the later Ordovician. In the deeper parts of the palaeobasin (Central Baltoscandian confacies belt including the Livonian Tongue) the several different types, clearly determined by changes in environment, occur: Relatively low diversity associations in the red-coloured sediments, a well-defined assemblage associated with black shales and more diverse associations in the argillaceous carbonate deposits. The appearance and distribution of some shortlived associations including immigrants to the Baltic (Dactylogonia and Rhynchotrema during the Keila-Oandu event, the Holorhynchus association during the mid-Ashgill and the Hirnantia fauna during the late Ashgill) are probably associated with climatic and sea-level changes in the palaeobasin.
Keywords: Brachiopods, Ordovician, distribution, biofacies differentiation, Baltoscandia
Addresses:
Linda Hints [ Linda [dot] Hints [at] gi [dot] ee ], Institute of Geology, Tallinn Technical University, Estonia Ave 7, 10143 Tallinn, Estonia and David A.T. Harper [ dharper [at] savik [dot] geomus [dot] ku [dot] dk ], Geologisk Museum, Københavns Universitet, Øster Voldgade 5-7, DK-1350 København K, Danmark. 12 January 2002.
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Brachiopod macrofaunal distribution through the upper Volkhov – lower Kunda (Lower Ordovician) rocks, Lynna River, St. Petersburg region
Hansen, J. & Harper, D.A.T. 2003–04–30: Brachiopod macrofaunal distribution through the upper Volkhov – lower Kunda (Lower Ordovician) rocks, Lynna River, St. Petersburg region. Bulletin of the Geological Society of Denmark, vol. 50, pp. 45–53, Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-03
Abstract: The ranges of 27 brachiopod species, through the upper Volkhov-lower Kunda interval of the Lynna River section, are presented on the basis of over 17,500 specimens. Three depth-related ecological associations are recognized within the succession of alternating limestones and marls forming part of an array of nearshore to mid-shelf communities in an intracratonic setting. Faunal diversity is relatively stable throughout the section with little evidence for abrupt local extinctions or originations. The dominant orthoid and clitambonitoid assemblages, however, form the basis of the distinctive Baltic brachiopod province developed during this time interval.
Keywords: Brachiopods, Volkhov, Kunda, Lynna River, biodiversity, brachiopod assemblages.
Addresses:
Jesper Hansen, Geological Museum, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark (Present address: Tromsø University Museum, NO-9037 Tromsø, Norway) & David A.T. Harper [ dharper [at] savik [dot] geomus [dot] ku [dot] dk], Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. 2 January 2002.
Diversification patterns in the clitambonitoid brachiopods of the Ordovician of Baltoscandia
Vinn, O. & Harper, D.A.T. 2003–04–30: Diversification patterns in the clitambonitoid brachiopods of the Ordovician of Baltoscandia. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 55–61, Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-04
Abstract: Two intervals of clitambonitoid diversification followed by major extinctions have been recorded in the Ordovician rocks of Baltoscandia, one during the Arenig and a second in the mid Caradoc. The Arenig radiation was characterized by high origination and extinction rates of both genera and species associated with the development of carbonate environments across the region. In addition the migration of numerous stocks of clitambonitoids out of Baltica to a number of other palaeocontinents occurred during this diversity peak during the Arenig, together with the spread of the majority of genera into a range of more local environments. A marked extinction in the Early Llanvirn coincided with shifts in sedimentation patterns whereas the diversity hike in the Mid Caradoc reflects the diversification of clitambonitoid species in both inner and outer shelf environments. The later Caradoc extinction coincided with an extensive eustatic regression event and the major restructuring of the ecosystem and brachiopod fauna. The final extinction of Baltic clitambonitoids in the late Ashgill was gradual and probably reflected an increasing dependence on more restricted niches.
Keywords: Brachiopods, Ordovician, Baltoscandia, Clitambonitoidea, biodiversity.
Addresses:
Olev Vinn [ ovinn [at] nickel [dot] laurentian [dot] ca ], Department of Earth Sciences, Laurentian University, Sudbury, Ontario, Canada P3E 2C6 (Present address: Institute of Geology, University of Tartu, Tartu 51014, Estonia). David A.T. Harper [ dharper [at] savik [dot] geomus [dot] ku [dot] dk ], Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. 19 April 2003.
Conodonts and brachiopods from the Volkhov Stage (Lower Ordovician) microbial mud mound at Putilovo Quarry, north-western Russia
Tolmacheva T., Fedorov P. & Egerquist E. 2003–04–30: Conodonts and brachiopods from the Volkhov Stage (Lower Ordovician) microbial mud mound at Putilovo Quarry, north-western Russia. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 63–74, Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-05
Abstract: Microbially mediated clay mud mounds are widely developed in the Lower Ordovician succession east of St. Petersburg (Russia) and are associated with a diverse and abundant fauna of brachiopods, ostracodes, echinoderms, bryozoans and conodonts. The lithology of one such mud mound in Putilovo Quarry has previously been studied, but the faunas associated with the mounds have not been investigated to date. Clay lenses in the Putilovo mud mound yield conodont assemblages belonging to the Baltoniodus triangularis and lowermost part of the Paroistodus originalis zones and these stratigraphical intervals are much thicker in the mud mound than in the coeval Lower Ordovician succession lateral to the mound. The compositions of the conodont and brachiopod assemblages are generally the same in the mud mound as in contemporaneous beds. The occurrence of relatively fewer conodont elements in the mud mound than in the surrounding successions probably indicates the higher rate of accumulation of the mud mound clays. Juvenile brachiopods are more numerous in the clays of the mud mound than outside the build-up, supporting the hypothesis that the mounds included ecologically stressed environments.
Keywords: Microbial mud mounds, conodonts, brachiopods, Lower Ordovician, Russia.
Addresses:
T. Tolmacheva, All Russian Geological Institute, Sredny 74, 199106 St. Petersburg, Russia., E. Egerquist, Department of Earth Sciences, University of Uppsala, Historical Geology and Palaeontology, Norbyvägen 22, SE-752 36 Uppsala, Sweden. P. Fedorov, Department of Historical Geology, St. Petersburg State University, 7/9 Universitetskaja emb., 199034, St. Petersburg, Russia. 24 August 2001.
An integrated biostratigraphical analysis of the Volkhov–Kunda (Lower Ordovician) succession at Fågelsång, Scania, Sweden
Stouge, S. & Nielsen, Arne T. 2003–04–30: An integrated biostratigraphical analysis of the Volkhov –Kunda (Lower Ordovician) succession at Fågelsång, Scania, Sweden. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 75–94. Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-06
Abstract: The Komstad Limestone is composed of dark grey to black micritic limestone deposited in an outer shelf environment on the margin of the East European Platform. It represents an interval of low sea level during the late Volkhov to early Kunda that led to the spread of limestones into the shale-dominated western lithofacies belt.
The Baltoniodus norrlandicus, Lenodus antivariabilis, Lenodus variabilis, Yangtzeplacognathus crassus and Lenodus pseudoplanus conodont zones were identified in the upper Volkhov to lower Kunda interval. Based on the most recent taxonomic and biostratigraphical framework, the Megistaspis limbata (with two subzones), Asaphus expansus and Asaphus raniceps trilobite zones were identified. A shale intercalation in the lower part of the Komstad Limestone contains the graptolites Phyllograptus cor in association with Glyptograptus sp. and is referred to Darriwilian 1 (Upper Arenig). In the Baltoscandian zonation this matches the upper part of the Didymograptus hirundo graptolite Zone. The upper level of the Komstad Limestone and the basal part of the overlying Almelund Shale do not contain graptolites, whereas the succeeding black shales of the Almelund Shale belong to the Holmograptus lentus Zone (Llanvirn). The Arenig-Llanvirn boundary is situated at or very near the top of the Komstad Limestone.
The conodont assemblage in the lower part of the Komstad Limestone at Fågelsång is associated with forms of Gondwanan affinity, which probably reflects the cool water environment of the outer shelf setting. The higher part of the limestone contains the Whiterockian conodont species Dzikodus sp. and Histiodella tableheadensis. These important Laurentian forms occur together with abundant Gothodus sp. 1 and Cyclopyge umbonata in the base of the Asaphus expansus Zone. The arrival of the Laurentian taxa – as well as Cyclopyge with an ‘Gondwana’ affinity – is related to a transient sea level rise at the base of the A. expansus trilobite Zone.
Keywords: Komstad Limestone, Almelund Shale, Fågelsång, Scania, Sweden, biostratigraphy, conodonts, trilobites, graptolites, Volkhov and Kunda stages, Arenig–Llanvirn boundary, Lower Ordovician.
Addresses:
Svend Stouge [ ss [at] geus [dot] dk ], Geological Survey of Denmark & Greenland, Øster Voldgade 10 DK-1350, Copenhagen K, Denmark. Arne Thorshøj Nielsen, [ arnet [at] savik [dot] geomus [dot] ku [dot] dk ], Geological Museum, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark; 15th July 2002.
The Asaphus raniceps problem in the Ordovician of Sweden
Bergström, J., Zhou Zhi-Qiang, Zhou Zhi-yi & Yuan Wen-Wei 2003–04–30: The Asaphus raniceps problem in the Ordovician of Sweden. Bulletin of Geological Society of Denmark, Vol. 50, pp. 95–104, Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-07
Abstract: It has been repeatedly stated that the lower Llanvirn Asaphus raniceps described by Dalman in 1827 and by Angelin in 1854 may represent two different species. This has forced us to live with the concepts of both A. raniceps Dalman and A. ‘raniceps’ sensu Angelin, and with a zone of A. ‘raniceps’ where A. raniceps is supposedly not present. However, new considerations based on large old and new collections have led to the firm conclusion that Angelin was correct in his identification of Dalman’s species. What has been regarded recently as the true Asaphus raniceps, at least by Tjernvik & Johansson in 1980 and by Nielsen in 1995, is instead identical with another generally misidentified species, Asaphus fallax Angelin 1854.
Keywords: Ordovician, Baltoscandia, trilobites, Asaphus, Dalman, Angelin.
Addresses:
Jan Bergström [ jan [dot] bergstrom [at] nrm [dot] se ], Swedish Museum of Natural History, P.O. Box 50007, SE-104 05 Stockholm, Sweden. Zhou Zhi-Quiang [ xigmrx [at] pub [dot] xaonline [dot] com ], X’ian Institute of Geology and Mineral Resources, 166 East You Yi Road, Xi’an, People’s Republic of China. Zhou Zhi-Yi [zyizhou [at] pub [dot] jlonline [dot] com ] & Yuan Wen-Wei, Nanjing Institute of Geology and Palaeontology, Academia Sinica, 39 East Beijing Road, Nanjing 210008, People’s Republic of China. 16 August 2001.
Upper Arenig trilobite biostratigraphy and sea-level changes at Lynna River near Volkhov, Russia
Hansen, T. & Nielsen, A.T. 2003–04–30: Upper Arenig trilobite biostratigraphy and sea-level changes at Lynna River near Volkhov, Russia. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 105– 114, Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-08
Abstract: Over 5000 trilobites have been collected from Lower Ordovician rocks exposed at the Lynna River in the Volkhov region, east of St. Petersburg, Russia. Bed-by-bed sampling has been carried out through the upper part of Volkhov Formation (top of Jeltiaki Member and the entire Frizy Member), the Lynna Formation and the basal part of the Obukhovo Formation. This interval, which is 7.5 metres thick, correlates with the upper part of the Arenig Series, and presumably even ranges into the very base of the Llanvirn. A preliminary biostratigraphical investigation of top Jeltiaki Member (BIIβ), Frizy Member (BIIγ) and basal Lynna Formation (BIIIα) reveals a rather continuous faunal turnover lacking sharp boundaries, and the biostratigraphical zonation (BIIβ–BIIIα) is primarily defined by the index trilobite taxa. The trilobite ranges are generally in agreement with the pattern described by Schmidt in 1907. The abundance ratio between Asaphus and the ptychopygids seems to be related to changes in relative sea level with Asaphus preferring the most shallow water conditions. A tentative interpretation of sea-level changes suggests an initial drowning at the base of BIIγ, immediately followed by a lowstand that in turn was succeeded by a moderate sea-level rise and then a significant fall. The last marks the BIIγ/BIIIα boundary. Correlation with sections in Scandinavia suggests that the basal part of BIIγ is strongly condensed.
Keywords: Biostratigraphy, trilobites, Arenig, Volkhov–Kunda boundary, Lynna River, East Baltic, sea-level variations.
Addresses:
T. Hansen, Geological Museum, Øster Voldgade 5–7, DK-1350 Copenhagen K, Denmark (Present address: Palaeontological Museum, Sars gate 1, Oslo 5, Norway). A.T. Nielsen [ arnet [at] savik [dot] geomus [dot] ku [dot] dk ], Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen, Denmark. 30 November 2001.
Biotic effects of the Ordovician Kinnekulle ash-fall recorded in northern Estonia
Hints, O., Hints, L., Meidla, T. & Sohar, K. 2003–04–30: Biotic effects of the Ordovician Kinnekulle ash-fall recorded in northern Estonia. Bulletin of the Geological Society of Denmark vol. 50, pp. 115– 123. Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-09
Abstract: The Late Ordovician (455 Ma) Kinnekulle volcanic ash-fall represents one of the largest ash eruptions known in Phanerozoic history. The dynamics of ostracodes, polychaete annelids and some shelly macrofauna across the Kinnekulle Bed in the Pääsküla section, northern Estonia indicate some significant faunal changes. The ostracod assemblage underwent major reorganization, including the replacement of predominant forms, a drop in taxon frequency and species diversity, and the probable extinction of some species following the ash-fall. The abrupt response of ostracodes indicates that the sediment surge and the resulting seafloor environment significantly affected the ostracodes. Jaw-bearing polychaetes (as represented by scolecodonts) display changes in their diversity curve and in the abundance of individual species above the altered ash layer. This change occurred after some delay indicating that polychaetes were not affected directly by the sediment influx but indirectly, probably by a change in their relationships with other biotas during a gradual rearrangement of seabed communities triggered by the ash-fall. Macrofaunal data also contains some evidence of the possible direct effects of the ash-fall. Thus, the biotic effects of the Kinnekulle ash-fall were probably larger than previously suggested. Many benthic organisms were strongly affected and the influence of this event persisted some time after the ash-fall.
Keywords: Ordovician, K-bentonites, volcanic ash-falls, biotic effects, ostracodes, scolecodonts.
Addresses:
Olle Hints [ Olle [dot] Hints [at] gi [dot] ee ], Linda Hints [ Linda [dot] Hints [at] gi [dot] ee ], Institute of Geology, Tallinn Technical University, Estonia Ave 7, 10143 Tallinn, Estonia; Tõnu Meidla [tmeidla [at] ut [dot] ee], Kadri Sohar [ vilk [at] ut [dot] ee ], Institute of Geology, Tartu University, Vanemuise 46, 51014 Tartu, Estonia. 15 October 2001.
Lower Ordovician mud mounds from the St. Petersburg region, northwestern Russia
Federov, P. 2003–04–30 Lower Ordovician mud mounds from the St. Petersburg region, northwestern Russia. Bulletin of the Geological Society of Denmark 50, pp. 125–137. Copenhagen.
https://doi.org/10.37570/bgsd-2003-50-10
Abstract: Hecker-type mud mounds are calcareous-clay buildups occurring in the Lower Ordovician (Billingen and Volkhov regional stages), condensed cool-water carbonates of northwestern Russia. The unusual feature of these buildups is the dominance of terrigenous clay in their cores. In all the buildups an initial gently-sloping mound of unconsolidated fossiliferous clay rests on a hardground surface. A layer of microsparite overlies the clay, with another hardground surface on the top. The mud mounds vary in diameter from tens centimetres to hundreds metres. Large mounds form complex multi-storey structures and contain sedimentary facies, which differ markedly from the facies of surrounding rocks. There is evidence that siliceous sponges formed these mud mounds. The Hecker-type mud mounds are moderate to cold-water sponge buildups with a unique combination of features found in their cold and warm water Phanerozoic counterparts.
Keywords: Mud mounds, sponges, facies, Ordovician, Russia.
Addresses:
Petr V. Fedorov [ fedorov [at] GG2686 [dot] spb [dot] ru ], Department of Historical Geology, Geological Faculty, St. Petersburg State University, 7/9 University Embankment, 199034, St. Petersburg, Russia. 17 October 2002.
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Prehistoric settlements and Holocene relative sea-level changes in northwest Sjælland, Denmark
Hede, S.U. 2003–12–15: Prehistoric settlements and Holocene relative sea-level changes in northwest Sjælland, Denmark. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 141–149. © 2003 by Geological Society of Denmark. ISSN 0011–6297.
https://doi.org/10.37570/bgsd-2003-50-11
Abstract: The topographic and geographic distribution of the Mesolithic and Neolithic habitations seen today in the Saltbæk Vig area, north-west Sjælland are directly related to relative sea-level changes of the Littorina Sea. The archaeological data indicate that the settlements changed their topographic positions from lower to higher ground. This pattern is explained by a rising relative sea-level during the Atlantic and early Subboreal period. Geological investigations of this phenomenon focused on changes in relative sea-level documented by the sedimentary record. At Smakkerup Huse, a late Mesolithic site, a sequence of stacked transgressive and regressive sediment deposits confirmed that the occupation coincided with a slowing rate of relative sea-level rise and beginning of relative sea-level fall during the late Atlantic period. The timing of the changes in relative sea-level was obtained by radiocarbon measurements of wood and bone fragments together with implements retrieved from contemporaneous sediment deposits. A rise in relative sea-level during the early Subboreal forced the inhabitants at Smakkerup Huse and in the Saltbæk Vig area to relocate to higher grounds.
Keywords: Holocene, relative sea-level changes, Littorina transgressions, Sjælland, Denmark, sequence stratigraphy, Mesolithic and Neolithic settlements.
Addresses:
Signe Ulfeldt Hede [ signeuh [at] geo [dot] geol [dot] ku [dot] dk ], Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
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Salix polaris leaves dated at 14.3 ka BP from northern Jylland
Korsager, B., Bennike, O. & Houmark-Nielsen, M. 2003–12–15: Salix polaris leaves dated at 14.3 ka BP from northern Jylland, Denmark. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 151– 155, Copenhagen. © 2003 by Geological Society of Denmark. ISSN 0011–6297.
https://doi.org/10.37570/bgsd-2003-50-12
Abstract: Leaves of the tiny willow Salix polaris Wahlenberg from a lake deposit in northern Jylland have been dated to c. 14,300 cal. years BP. These are some of the oldest dated plant remains after the last deglaciation from an on-shore deposit in Denmark. Salix polaris was probably one of the first woody plants that immigrated to Denmark, where it played an important role on the raw, carbonate rich but unstable soils.
Keywords: Late-glacial, Denmark, macrofossils, Salix polaris, palaeoenvironments.
Addresses:
B. Korsager [ bjarke [at] korsager [dot] org ], Århusgade 107, 3tv, DK-2100 Copenhagen Ø, Denmark¸O. Bennike, Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark & M. Houmark-Nielsen, Geological Institute, Copenhagen University, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Stratigraphy and sea-level fluctuations in the Upper Miocene Gram Formation, south-western Denmark
Hansen, J. & Hansen, T. 2003–12–15: Stratigraphy and sea-level fluctuations in the Upper Miocene Gram Formation, south-western Denmark. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 157–169, Copenhagen. © 2003 by Geological Society of Denmark. ISSN 0011–6297.
https://doi.org/10.37570/bgsd-2003-50-13
Abstract: Correlation between four published and one unpublished lithological logs from the Gram clay pit permits a comparison between previous studies of this critical exposure. The boundary between the Gram Clay and the Gram Silt in the Gram clay pit is redefined. A sea-level curve, based mainly on foraminiferal data from the Sæd, Gram and Lille Tønde borings in southern Jutland, is constructed and compared with a published sea-level curve from the North Sea. It appears that sea level recorded from southern Jutland was controlled mainly by eustacy.
Keywords: Denmark, Gram Formation, Miocene, lithostratigraphy, sea-level fluctuations.
Addresses:
J. Hansen [ jesper [at] tmu [dot] uit [dot] no ], Tromsø Museum Universitetsmuseet, Lars Thørrings vei 10, N-9037 Tromsø, Norway and T. Hansen [thoha [at] nhm [dot] uio [dot] no], Geological Museum, Boks 1172 Blindern, N-0318 Oslo, Norway. 28 October 2003.
Alteration of detrital Fe-Ti oxides in Miocene fluvial deposits, central Jutland, Denmark
Weibel, R. 2003–12–15: Alteration of detrital Fe-Ti oxides in Miocene fluvial deposits, central Jutland, Denmark. Bulletin of the Geological Society of Denmark, Vol. 50, pp. 171–183. Copenhagen. © 2003 by Geological Society of Denmark. ISSN 0011–6297.
https://doi.org/10.37570/bgsd-2003-50-14
Abstract: Miocene fluvial sands from an outcrop at Voervadsbro in central Jutland were studied to assess the Fe-Ti oxides and their alteration products forming during a warm, humid climate and under the influence of scattered organic material. The opaque minerals and their alteration products were investigated by optical light microscope, reflection microscope, microprobe, scanning electron microscope and X-ray diffraction. The detrital Fe-Ti oxides consist of, in decreasing order, ilmenite, titanomagnetite, magnetite, rutile, hematite and silicified leucoxene. Degradation of organic matter created mildly reducing and neutral-acid conditions under which the Fe-Ti oxides (ilmenite, titanomagnetite, magnetite and hematite) were unstable. Ilmenite has a three-step alteration process: ilmenite → pseudorutile → fine leucoxene → coarse leucoxene (single crystals of rutile or anatase). Alteration of titanomagnetite commonly resulted in coarse leucoxene in a trellis texture. Alteration of ilmenite lamellae in titanomagnetite is typically complete, probably because of their small size compared to ilmenite grains. Colloidal leucoxene is an alteration product of ilmenite and titanomagnetite. The formation of colloidal leucoxene seems to be related to organic matter or elements associated with it. Magnetite has been partly dissolved, preferentially around the rim and along fissures. Hematite is rarely a detrital grain due to intensive dissolution, and the exsolution lamellae of hematite are invariably more altered than the ilmenite host. Oxidising conditions prevailed locally e.g. in coarse-grained foresets without organic material and at the atmospheric interface of bogs. In this environment dissolved iron (originating from the alteration of Fe-Ti oxides) precipitated mainly as goethite.
Keywords: Alteration, Fe-Ti oxides, ilmenite, pseudorutile, leucoxene, colloidal leucoxene, titanomagnetite, hematite, Miocene, Odderup Formation, fluvial sands, organic material, warm temperate – subtropical climate.
Addresses:
Rikke Weibel [ weibel [at] mail [dot] dk ], Department of Earth Sciences, University of Aarhus, DK-8000 Aarhus C, Denmark. Current address: Skamol A/S, Skarrehagevej 26, DK-7900 Nykøbing Mors, Denmark. 4 July 2003.
Trace fossils from the Lower and Middle Jurassic marginal marine deposits of the Sorthat Formation, Bornholm, Denmark
Bromley, R.G. & Uchman, A. 2003–12–18. Trace fossils from the Lower and Middle Jurassic marginal marine deposits of the Sorthat Formation, Bornholm, Denmark. Bulletin of the Geological Society of Denmark, Vol. 52, pp. 185–208. Copenhagen. © 2003 by Geological Society of Denmark. ISSN 0011–6297.
https://doi.org/10.37570/bgsd-2003-50-15
Abstract: The Lower to Middle Jurassic Sorthat and Bagå Formations of the Baltic island of Bornholm, Denmark, are a predominantly fluviatile unit. On the south coast of the island at Korsodde, however, an interval within the Sorthat Formation contains a diverse trace fossil assemblage indicating a marine incursion. Study of this interval revealed 15 ichnotaxa, among which one is new: Bornichnus tortuosus nov. igen. et isp. Several of the trace fossils present are generally considered characteristic of the lower shoreface to offshore environments (e.g. Teichichnus and Asterosoma). However, the low degree of bioturbation and ichnodiversity, and sedimentological features, indicate an environment influenced by salinity fluctuation, probably a tidally influenced delta. Five ichnofabrics are defined that describe this setting and which may be indicative of marginal-marine environments that are influenced by salinity fluctuations.
Keywords: Ichnofabrics, trace fossils, palaeoenvironmental analysis, Jurassic, Denmark, Bornichnus, Diplocraterion, Asterosoma
Addresses:
Richard G. Bromley [ rullard [at] geo [dot] geol [dot] ku [dot] dk ], Geological Institute, Copenhagen University, Øster Voldgade 10, DK-1350 København K, Denmark. Alfred Uchman [fred [at] geos [dot] ing [dot] uj [dot] edu [dot] pl]