Bulletin of the Geological Society of Denmark • Volume 51/2
 | ContentsRasmussen, E.S.:Stratigraphy and depositional evolution of the uppermost Oligocene – Miocene succession in western Denmark.
Graversen, O. : Upper Triassic – Cretaceous stratigraphy and structural inversion offshore SW Bornholm, Tornquist Zone, Denmark.
Stemmerik, L. & Piasecki, S. : Isotopic evidence for the age of the Røde Ø Conglomerate, inner Scoresby Sund, East Greenland.
Willumsen, P.S. : Palynology of the Lower Eocene deposits of northwest Jutland, Denmark.
Pedersen, G.K., Pedersen, S.A.S., Steffensen, J. & Pedersen, C.S. : Clay content of a clayey diatomite, the Early Eocene Fur Formation, Denmark
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Stratigraphy and depositional evolution of the uppermost Oligocene –Miocene succession in western DenmarkRasmussen, E.S. 2004–12–15: Stratigraphy and depositional evolution of the uppermost Oligocene –Miocene succession in western Denmark. Bulletin of the Geological Society of Denmark, Vol. 51, pp. 89–109. © 2004 by Geological Society of Denmark. ISSN 0011–6297.
Abstract: The uppermost Oligocene – Miocene succession in Denmark is subdivided into six depositional sequences. The development of the succession was controlled both by tectonic movements and eustatic sea-level changes. Tectonic movements generated a topography, which influenced the depositional pattern especially during low sea level. This resulted in sediment by-pass on elevated areas and the confinement of fluvial systems to structural lows. Structural highs further created restricted depositional environments behind the highs during low sea level. The structural highs were also the locus for sandy spit deposits during transgression and high sea level. Initially sediment supply was from the north and north-east but shifted within the Middle Miocene to an easterly direction indicating a significant basin reorganisation at this time. Eustatic sea-level changes mainly controlledthe timing of sequence boundary development and the overall architecture of the sequences.Consequently, the most coarse-grained sediments were deposited within the forced regressive wedge systems tract, the lowstand systems tract and the early transgressive systems tract. The most distinct progradation occurred in the Aquitanian (Lower Miocene) and was associated with a cold period in central Europe.The subsequent rise of sea level until the Serravallian (Middle Miocene) resulted in an overall back-stepping stacking pattern of the sequences and in decreasing incision.
Key words:Oligocene, Miocene, North Sea, Denmark, eustacy, climate, tectonics, sequence stratigraphy.
Address: Erik Skovbjerg Rasmussen [
], Geological Survey of Denmark and Greenland, Øster Voldgade10, DK-1350 Copenhagen K.
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Upper Triassic – Cretaceous stratigraphy and structural inversion off-shore SW Bornholm, Tornquist Zone, Denmark Graversen, O. 2004–12–15: Upper Triassic – Cretaceous stratigraphy and structural inversion off-shore SW Bornholm, Tornquist Zone, Denmark. Bulletin of the Geological Society of Denmark, vol. 51,pp. 111–136.
Abstract: Geological interpretations by various authors of exploration reflection seismic data offshore SW Bornholm show good agreement for the Rønne Graben. However, major differences exist regarding the Mesozoic stratigraphy and structural development of the Arnager-Darlowo Block and the Risebæk Graben. Major problems relate to the distribution and structural position of the Jurassic, and interpretation of inversion structures in the Rønne and Kolobrzeg grabens along the Arnager Block. In addition to the Pernille-1 and Stina-1 wells that document the stratigraphy of the Rønne and Kolobrzeg graben sections, the bedrock geology along the south coast of Bornholm is discussed.The Jurassic is established as a major constituent of the Arnager Block above the Risebæk Graben, in contrast to previous interpretations. The revised stratigraphy and reinterpretation of the inversion zones help to establish a new interval of basin inversion during the Jurassic – Early Cretaceous priorto the Late Cretaceous inversion. Analysis of the Late Cretaceous inversion across the Rønne Graben supports the proposed revision of the stratigraphy and leads to a new model. Previous interpreta-tions invoked a major uplift of the graben along a reverse fault at the eastern border of the Rønne Graben. In the new model, Late Cretaceous inversion across the Rønne Graben is associated withtilting of the graben during differential subsidence/uplift of the Skurup Platform and the Arnager Block, whereas reverse faulting was limited.
Key words: Inversion, Tornquist Zone, Rønne Graben, Arnager Block, Bornholm.
Address: Ole Graversen [oleg@geol.ku.dk], Geological Institute, University of Copenhagen, Geocenter København, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
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Isotopic evidence for the age of the Røde Ø Conglomerate, inner Scoresby Sund, East GreenlandStemmerik, L. & Piasecki, S. 2004–12–15: Isotopic evidence for the age of the Røde Ø Conglomerate, inner Scoresby Sund, East Greenland. Bulletin of the Geological Society of Denmark, vol. 51, pp. 137–140. © 2004 by Geological Society of Denmark. ISSN–6297.
Abstract: On the basis of sulphur and strontium isotope data of sedimentary gypsum it is suggested that the Røde Ø Conglomerate at C. Hofmann Halvø, East Greenland was deposited during the mid to late Permian. The δ34S values of +11.4\\\\\\‰ and +11.9\\\\\\‰ are comparable to late Permian seawater values whereas 87Sr/86Sr ratios of 0.7188137 and 0.7191609 indicate the influence of freshwater. This proposed mid to late Permian age for the Røde Ø Conglomerate makes it an equivalent to the Huledal Formation in the Jameson Land – East Greenland basins to the north-east.
Key words: Permian, Røde Ø Conglomerate, gypsum, isotopes.
Addresses:Lars Stemmerik [
] & Stefan Piasecki [
], Geological Survey of Denmark and Green-land, Øster Voldgade 10, DK–1350 Copenhagen K, Denmark.
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Palynology of the Lower Eocene deposits of northwest Jutland, Denmark Willumsen, P.S. 2004–12–15: Palynology of the Lower Eocene deposits of northwest Jutland, Denmark. Bulletin of the Geological Society of Denmark. Vol. 52, pp. 141–157, Copenhagen. © 2004 by Geological Society of Denmark. ISSN–6297.
Abstract: Early Eocene spores and pollen assemblages from the uppermost part of the Stolle Klint Clay and the overlying Fur Formation are diverse and well preserved. The terrestrial microflora comprises 42 species of spores and 108 species of pollen and four spores and pollen zones are established i.e. Interpollis velum-Labrapollis globosus, Basopollis atumenscens, Basopollis orthobasalis and Thomsonipollis magnificus zones. The zones are directly correlated to the existing tephra-chronology and stratigraphy. The dinoflagellate cysts assemblages are referred to Zones 6 and 7 of Heilmann-Clausen or the upper part of the Apectodinium hyperacanthum and Glaphyrocysta ordinata Interval Biozone of Powell. A marked shift in the terrestrial and marine palynomorph assemblages takes place at the transitionbetween the two oldest spore and pollen zones at c. 1.2 m below ash layer –19b.
Key words: Palynology, early Eocene, spores and pollen, Stolle Klint Clay, Fur Formation, tephra-chronology, biostratigraphy, correlation.
Address: Pi Suhr Willumsen [
], Department of Geosciences, University of Oslo, P.O. Box1047, Blindern, NO-0316 Oslo, Norway.
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Clay content of a clayeydiatomite, the Early Eocene Fur Formation, Denmark Pedersen, G.K., Pedersen, S.A.S., Steffensen, J. & Pedersen, C.S. 2004–12–15. Clay content of a clayeydiatomite, the Early Eocene Fur Formation, Denmark. Bulletin of the Geological Society of Denmark,Vol. 51, pp. 159–177. © 2004 by Geological Society of Denmark. ISSN 0011–6297.
Abstract: The Early Eocene Fur Formation is a clayey diatomite interbedded with layers of volcanic ash. The diatomite is non-calcareous, laminated or structureless, and thin sections show that the proportion of clay-sized particles to diatom frustules varies between laminae. The clay mineral phase has been isolated and its chemical composition has been determined by X-ray fluorescence (XRF). Clay mineralogical analyses based on X-ray diffraction (XRD) show that the dominant phase is smectite. A general formula for the clay mineral phase is: X0.1K0.2(Mg0.3Fe(III)0.3–0.7Al1.1–1.4)Si4O10(OH)2.The investigation indicates that the clayey diatomite of the Fur Formation comprises three components: diatom frustules, clay minerals and volcanic dust. The chemical compositions of bulk samples have been determined. The clay mineral content is calculated to be 30–45% (by weight). Volcanic dust constitutes c. 10% of the diatomite, and the rest is diatoms (opal-A). The diatom frustules contain some Al2O3 that is either of primary or diagenetic origin.
Key words: Diatomite, clay minerals, chemical composition, Fur Formation, Early Eocene, Denmark.
Addresses: Gunver Krarup Pedersen [
], Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Stig A. Schack Pedersen [
], Geological Sur-vey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Jacob Steffensen[
] Geological Institute, University of Copenhagen, present address: Falkenberg A/S Miljørådgivning, Vassingerødvej 145, DK-3540 Lynge .
Christian Schack Pedersen [
] Institute of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
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