Contents of 49/1
Obst, K., Böhnke, A., Katzung, G. & Maletz, J.:
Pb-Pb zircon dating of tuff horizons inthe Cyrtograptus Shale (Wenlock, Silurian) of Bornholm
Pålsson, C.:
Upper Ordovician graptolites and biostratigraphy of the Röstånga 1 core,Scania, S. Sweden..
Kilda, L. & Friis, H.:
The key factors controlling reservoir quality of the Middle Cambrian Deimena Group sandstone in West Lithuania
Bergström, S. M., Larsson, K., Pålsson, C. & Ahlberg, P.:
The Almelund Shale, a replacement name for the Upper Didymograptus Shale and the Lower Dicellograptus Shale in the lithostratigraphical classification of the Ordovician succession in Scania, Southern Sweden
Machalski, M.:
Danian ammonites: A discussion.
Walaszczyk, I., Cobban, W.A. & Odin, G.S.:
The inoceramid succession across the Campanian – Maastrichtian boundary
Madirazza, I.:
The influence of tectonics on the land forms in west Jutland, Denmark
Gregersen, S.:
Earthquakes and change of stress since the ice age in Scandinavia
Krissek, L.A. & St.John, K.E.K.:
Pleistocene iceberg production from East Greenland: Synchronous between source areas, but distinct from global ice volume
Book reviews:
Mortimore, R.N., Wood, C.J. & Gallois, R.W. 2001: British Upper Cretaceous Stratigraphy. Geological Conservation Review Series 23, xx + 558 pp. Joint Nature Conservation Committee, Peterborough.
Download PDF (3,19 Mb)
https://doi.org/10.37570/bgsd-2003-49-15
Baldschuhn, R., Binot, F., Fleig, S. & Kockel, F. (compilers) 2001:: Geotektonischer Atlas von Nordwest-Deutschland und dem deutschen Nordsee-Sektor. Geologisches Jahrbuch A153, 88 pages and 3 CD-ROMs. By commission: E Schweizerbart’sche Verlagsbuchhandlung (Nägele u. Obermiller), Johannesstraße 3 A, D-70176 Stuttgart.
Download PDF (99,67 Kb)
https://doi.org/10.37570/bgsd-2003-49-16
Contents of 49/2
Frederiksen, S :
Quantitative dynamic modelling of basin development in the central and eastern North Sea region – coaxial stretching and strain localization.
Hansen, D.L., Blundell, D.J. & Nielsen, S.B.:
A Model for the evolution of the Weald Basin..
Gemmer, L., Nielsen, S.B. & Lykke-Andersen, H. :
Differential vertical movements in the eastern North Sea area from 3-D thermo-mechanical finite elemental modelling. B
Vejbæk, O.V. & Andersen, C. :
Post mid-Cretaceous inversion tectonics in the Danish Central Graben – regionally synchronous tectonic events?
Huuse, M. :
Late Cenozoic palaeogeography of the eastern North Sea Basin: climatic vs tectonic forcing of basin margin uplift and deltaic progradation.
Clausen, O. R. & Huuse, M.:
Mid-Paleocene palaeogeography of the Danish area.
Nielsen, S.B. :
A post mid-Cretaceous North Sea model.
Pb-Pb zircon dating of tuff horizons inthe Cyrtograptus Shale (Wenlock, Silurian) of Bornholm
Obst, K., Böhnke, A., Katzung, G. & Maletz, J.: Pb-Pb zircon dating of tuff horizons inthe Cyrtograptus Shale (Wenlock, Silurian) of Bornholm, Denmark. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 1–8, Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-01
Abstract: Waterlain fallout ashes are interbedded in the upper part of the Cyrtograptus Shale of Bornholm, theyoungest preserved member of the Lower Palaeozoic sequence at the southern coast of the island.Graptolite faunas indicate that these tuffaceous sediments belong to the Cyrtograptus lundgreni Zonedeposited during Late Wenlock. A 207Pb/206Pb mean age of 430 ± 1.9 Ma obtained by evaporation of idiomorphic single zircons from the tuff layers supports this observation. Geochemical studies of the pyroclastic rocks point to an explosive, calc-alkaline magmatic arc volcanism which probably occurred along or slightly south of the Tornquist-Teisseyre Lineament, and could have been induced by the collision of Avalonia with the southern margin of Baltica during the Silurian. This assumption is supported by the contemporaneous deposition of bentonites on the Swedish island of Gotland which might represent a distal facies of these fallouts. Further, the subduction-related volcanic activity is interpreted as a fingerprint for closing of the Tornquist Ocean during the Caledonian orogeny.
Keywords: Bornholm, Tornquist Ocean, Wenlock, Silurian, tuff, graptolites, Pb-Pb isotopes, singlezircon evaporation.
Addresses:
Karsten Obst [ obst [at] uni-greifswald [dot] de ], Gerhard Katzung & Jörg Maletz, Institut für GeologischeWissenschaften, Ernst-Moritz-Arndt-Universität Greifswald, Friedrich-Ludwig-Jahn-Str. 17a, D-17489Greifswald, Germany. Antje Böhnke [e-mail: aboehnke [at] rz [dot] uni-leipzig [dot] de], Institut für Geophysik und Geologie,Universität Leipzig, Talstr. 35, D-04103 Leipzig, Germany. 6 June 2000.
Upper Ordovician graptolites and biostratigraphy of the Röstånga 1 core,Scania, S. Sweden
Pålsson, C.: Upper Ordovician graptolites and biostratigraphy of the Röstånga 1 core, Scania, S. Sweden. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 9–23, Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-02
Abstract: A core drilling at Röstånga in 1997, referred to as Röstånga 1, penetrated a significant portion of the Upper Ordovician-Lower Silurian succession in this classical Lower Palaeozoic outcrop area in W central Scania. In descending order the Upper Ordovician of the core embraces the following units (stratigraphic thickness in parenthesis): Lindegård Mudstone (27.8 m), Fjäcka Shale (13.6 m), Mossen Formation (0.6 m), Skagen Formation (0.8 m), and Sularp Formation (19.9 m+). Graptolites are described from the Lindegård Mudstone, the Fjäcka Shale, and the Mossen Formation. The graptolites are classified into 12 taxa, among which 9 are identified to species. Graptolites are very rare in the Mossen Formation, which has yielded only two specimens of Pseudoclimacograptus scharenbergi.The Fjäcka Shale yielded a fairly diverse graptolite fauna, indicative of the Pleurograptus linearis Zone.This zone is succeeded by the Dicellograptus complanatus Zone, with the zonal index appearing in the lower part of the Lindegård Mudstone immediately above graptolites indicative of the P. linearisZone. No graptolites were recovered from the Skagen Formation and the Sularp Formation.
Keywords: Upper Ordovician, Pleurograptus linearis Zone, Dicellograptus complanatus Zone, graptolites,taxonomy, biostratigraphy, Röstånga, Scania, S. Sweden.
Addresses:
C. Pålsson [ christian [dot] palsson [at] geol [dot] lu [dot] se ], Department of Geology, Historical Geology and Palaeontology,Sölvegatan 13, SE-223 62 Lund, Sweden. 17 May 2001.
The key factors controlling reservoir quality of the Middle CambrianDeimena Group sandstone in West Lithuania
Kilda, L. & Friis, H.: The key factors controlling reservoir quality of the Middle CambrianDeimena Group sandstone in West Lithuania. Bulletin of the Geological Society of Denmark, Vol. 49, pp.25–39, Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-03
Abstract: Sandstones of the Middle Cambrian Deimena Group are commercially important as they make up the largest part of the hydrocarbon-bearing reservoir in 15 oil fields discovered in West Lithuania. However, the sandstones are characterised by a very complicated spatial distribution of reservoir quality. In order to better understand the distribution of reservoir properties and their controlling parameters, eighty-two sandstone samples from twenty-one boreholes were studied by means of thin section description, scanning electron microscopy, using backscattered and cathodoluminescence modes and clay fraction analyses. Generally, the sandstones are strongly cemented by quartz, resulting in almost total destruction of porosity but porous domains with preserved early stage quartz cement occur in a complex pattern. The close location of the early and late stage overgrowth types indicates that some sandstone parts were preserved from intense authigenic quartz precipitation. We believe that early carbonate cement was such an inhibitor. Detrital quartz grains in carbonate cemented domains are mostly free of authigenic quartz and as a rule show weakly compacted fabric as compared to the quartz cemented parts. Moreover, large secondary pores are located close to the carbonate cemented domains and indicate that some carbonate cement eventually dissolved. Apparently, the best reservoir properties within the generally strongly quartz cemented Deimena Groupsandstones are found in domains where dissolution of the early carbonate cement took place.
Keywords: Deimena Group, sandstone, porosity, quartz overgrowths, authigenic quartz, early carbonatecement.
Addresses:
Linas Kilda [ kil [at] geonafta [dot] lt ] Geological Institute of Lithuania, T. Šev…enkos 13, LT-2600, Vilnius, Lithuania.
Henrik Friis [ henrik [dot] friis [at] geo [dot] au [dot] dk ] Department of Earth Sciences, University of Aarhus, C.F. Møllers Allé120, DK-8000, Århus C, Denmark. 16. April 2002.
The Almelund Shale, a replacementname for the Upper Didymograptus Shale and the Lower Dicellograptus Shale in the lithostratigraphical classification of the Ordovician succession in Scania, Southern Sweden
Bergström, S. M., Larsson, K., Pålsson, C. & Ahlberg, P.: The Almelund Shale, a replacement name for the Upper Didymograptus Shale and the Lower Dicellograptus Shale in the lithostratigraphical classification of the Ordovician succession in Scania, Southern Sweden. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 41–47. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-04
Abstract: The formation name Almelund Shale is proposed for a lithostratigraphically defined unit to replace the outdated chronostratigraphical designations Upper Didymograptus Shale and Dicellograptus Shalein the Middle and lowermost Upper Ordovician succession in Scania. The Almelund Shale is a lithologically uniform unit of dark-grey to black shales with rare carbonate interbeds between the Komstad Limestone and the Sularp Shale. Apart from a diverse graptolite fauna it yields a few shelly fossils (mostly lingulate brachiopods) and biostratigraphically diagnostic conodonts and chitinozoans. In the type sections of the Almelund Shale along the Sularp Brook in the Fågelsång area, W-central Scania, the top of the unit is taken to be the base of the Fågelsång Phosphorite, and its basal contact is at the top of the underlying Komstad Limestone. Its total thickness in the Fågelsång drill-core is 28.32 m. The unit is widely distributed in the subsurface in a SE-NW belt across Scania.
Keywords: Ordovician, graptolite biostratigraphy, lithostratigraphy, Scania, Sweden.
Addresses:
S.M. Bergström [ stig [at] geology [dot] ohio-state [dot] edu ], Department of Geological Sciences, 155 S. Oval Mall, The Ohio State University, Columbus, Ohio 43210, USA. K. Larsson, C. Pålsson & P. Ahlberg, Department ofGeology, Division of Historical Geology and Palaeontology, Lund University, Sölvegatan 13, SE-223 62 Lund, Sweden. 20 August 2001
Danian ammonites: A discussion
Machalski, M.: Danian ammonites: A discussion. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 49–52, Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-05
Abstract: Possible ammonite survivors reported from the lowermost Danian deposits of Denmark (Stevns Klint) and The Netherlands (Curfs-Ankerpoort quarry) are questioned. Some of the specimens from Denmark are almost certainly reworked from the uppermost Maastrichtian deposits. As concerns the remainder of the reported material, reworking is also possible, at least theoretically. On the basis of Ockham’s Razor, the hypothesis that all specimens are reworked from the Maastrichtian strata must be preferred until compelling evidence for Danian survivors is proven. Such evidence may be potentially provided by articulated ammonite aptychi located in Danian deposits or by aptychi revealing Danian isotopic signals.
Keywords: K-Pg boundary, extinction, survival, ammonites, aptychi, reworking, hardgrounds, Danian, Maastrichtian, Denmark, Netherlands.
Addresses:
Marcin Machalski [ mach [at] twarda [dot] pan [dot] pl ] Instytut Paleobiologii PAN, ul. Twarda 51/55, PL – 00-818 Warszawa, Poland. 12 March 2002.
The inoceramid succession across the Campanian – Maastrichtian boundary
Walaszczyk, I., Cobban, W.A. & Odin, G.S.: The inoceramid succession across the Campanian – Maastrichtian boundary. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 53–60. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-06
Abstract: Recent study revealed a high correlation potential of inoceramid bivalves across the Campanian – Maastrichtian (Upper Cretaceous) boundary within the Euroamerican biogeographical region. In inoceramid terms the Campanian/Maastricthian boundary, as currently defined, lies in the topmost part of the “Inoceramus” redbirdensis Zone, close to the base of the Endocostea typica Zone. Both zones, as well as the whole late Campanian and early Maastrichtian inoceramid succession is well recognisable across the European sections and across the Atlantic to the US Western Interior succession.
Keywords: Inoceramid zonation, Campanian – Maastrichtian boundary, Euramerican biogeographical region, correlations.
Addresses:
Ireneusz Walaszczyk [ walas [at] geo [dot] uw [dot] edu [dot] pl ] , Institute of Geology, University of Warsaw, Al. Zwirki i Wigury 93, PL-02-089 Warszawa, Poland.
William A. Cobban, 70 Estes Street, Lakewood, Colorado 80226, USA.
Gilles S. Odin, Université P. & M. Curie, Unité de Géochronologie et Sédimentologie Océanique; 4, Place Jussieu, Case 119 A, F75252, Paris Cedex 05, France. 13 May 2002.
The influence of tectonics on the land forms in west Jutland, Denmark
Madirazza, I.: The influence of tectonics on the land forms in west Jutland, Denmark. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 63–72, Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-07
Abstract: The structural development and its influence on the present land forms is discussed on the basis of the reflection seismic and gravity data. The study area covers the western part of Jutland which was not glaciated during the Weichselian and is delimited by two Weichsel main stationary lines: the line extending from west to east and the line extending from north to south (these two lines join at Dollerup). The southern border of the study area corresponds approximately to the northern limit of the buried Ringkøbing-Fyn High. In this part of west Jutland the base Zechstein faults can be traced to the surface where they control the drainage system. The faults are mainly NW-SE trending strike slip faults which are active also at the present time. Zechstein evaporates are present in the entire area discussed here.
Keywords: gravity, seismics, strike slip faulting, neotectonics.
Addresses:
Ivan Madirazza, Department of Earth Sciences, Laboratory of Geophysics, University of Aarhus, Finlandsgade 6, DK-8200 Aarhus N, Denmark. 18 December 2001.
Quantitative dynamic modelling of basin development in the central and eastern North Sea region – coaxial stretching and strain localization
Frederiksen, S. 2002–12–02: Quantitative dynamic modelling of basin development in the central and eastern North Sea region – coaxial stretching and strain localization. Bulletin of the Geological Society of Denmark. Vol. 49, pp. 95–108. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-08
Abstract: A new two-dimensional dynamic lithosphere model is used to simulate the Late Palaeozoic to end Danian evolution of the Norwegian-Danish Basin and the post Permian evolution of the Central North Sea including the Central Graben. The transient heat equation and the equations of motion are solved using the finite element method. The lithosphere deforms by brittle and ductile processes through an elasto-visco-plastic rheology depending on temperature, pressure, strain-rate and material parameters. Strain softening dependent on accumulated strain is incorporated. Deposition, erosion and compaction of sediments are simulated. Results show that it is possible to satisfy observations of crustal structure, sediment thickness and surface heat flow for both basins taking all major tectonic and thermal events into consideration. The evolution of the Norwegian-Danish Basin is modelled using a Late Carboniferous – Early Permian thermal event, main rift phase in Early Permian and a minor extensional phase in Triassic. For the Central North Sea two thermal and three tectonic events are simulated: Late Carboniferous – Early Permian and Middle Jurassic thermal events, Early Triassic and Late Jurassic extension, and Late Cretaceous compression. Results show that strain softening may lead to strain localization during extension and therefore may explain observations of upper mantle dipping reflectors in the North Sea. A pure shear dominated extensional regime may change into a simple shear system.
Keywords: dynamic model, extension, strain softening, strain localization, the Norwegian-Danish Basin, the Central North Sea.
Addresses:
Susanne Frederiksen [ sus_fred [at] hotmail [dot] com ], Department of Earth Sciences, University of Aarhus, Finlandsgade 8, DK-8200 Århus, Denmark. 15 August 2001.
A Model for the evolution of the Weald
Hansen, D.L., Blundell, D.J. & Nielsen, S.B. 2002–12–02. A Model for the evolution of the Weald Basin. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 109–118. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-09
Abstract: The Weald Basin developed through the Jurassic–Lower Cretaceous as an extensional basin founded upon E–W trending low-angle faults that were probably Variscan thrusts, subsequently reactivated as normal faults. Later, the basin was inverted and uplifted into a broad dome, whilst the London Basin to the north, and the Hampshire–Dieppe Basin to the south, subsided as flanking basins during the late Palaeocene–Eocene. Seismic sections across the Weald indicate that inversion resulted from north-directed stress. A stratigraphic reconstruction based on a N–S profile across the Weald and flanking basins serves as a template for a forward, 2D thermo-mechanical model that simulates the evolution of the Weald Basin through crustal extension and its inversion, and subsidence of the flanking basins, through compression. The model provides a physical explanation for this sequence of events, requiring a region of crust of reduced strength relative to its flanks. This weak region is the location of crustal-scale Variscan thrusts that have been reactivated subsequently. The strong crust on the flanks is essential for the development of flanking basins during inversion and uplift of the Weald.
Keywords: Basin inversion, lithosphere, thermo-mechanical modelling, finite elements, visco-elastic- plastic, sedimentation, erosion.
Addresses:
David Lundbek Hansen [ david [at] geo [dot] au [dot] dk ] & Søren Bom Nielsen, Department of Earth Sciences, University of Aarhus, Finlandsgade 6, DK-8200 Aarhus N.
Derek J. Blundell, Department of Geology, Royal Holloway, University of London, England. 15 January 2001.
Differential vertical movements in the eastern North Sea area from 3-D thermo-mechanical finite elemental modelling
Gemmer, L., Nielsen, S.B. & Lykke-Andersen, H. 2002–12–02: Differential vertical movements in the eastern North Sea area from 3-D thermo-mechanical finite elemental modelling. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 119–128. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-10
Abstract: The response of a heterogeneous lithosphere to a compressional stress field is studied using a three-dimensional thermo-mechanical finite element model. Weak zones in the lithosphere thicken and act as loads that pull down the lithosphere in regions around the weak zones. Strong zones are subjected to less lithospheric thickening than the surroundings and produce surface depressions and uplift in the surrounding areas. The model is used to study the Late Cretaceous and Paleocene differential vertical movements in the eastern North Sea area. The Sorgenfrei-Tornquist Zone is assumed to be a pre-existing weak crustal zone, which inverts during compression and produces marginal basins by loading the lithosphere. The area of the Silkeborg Gravity High is an example of a pre-existing strong crustal zone which subsides during compression. Moho topography in the area gives rise to lateral strength variations, which result in surface uplift where Moho is deep and subsidence where Moho is shallow. These effects, together with the lateral variations of the thermal structure and the stress field, determine the overall Late Cretaceous-Paleocene distribution of vertical movements of the area. This has implications for the pattern of erosion, sediment transport and the distribution of sediment facies.
Keywords: Sorgenfrei-Tornquist Zone, inversion, Silkeborg Gravity High, eastern North Sea, Moho, Cenozoic, finite element.
Addresses:
Lykke Gemmer [ lykke [at] geo [dot] au [dot] dk ], Søren B. Nielsen & Holger Lykke-Andersen, Department of Earth Sciences, University of Aarhus, Finlandsgade 6-8, DK-8200 Århus, Denmark. 15 September 2001.
Download PDF (12,05 Mb)
Top
Post mid-Cretaceous inversion tectonics in the Danish Central Graben – regionally synchronous tectonic events?
Vejbæk, O.V. & Andersen, C. 2002–12–02: Post mid-Cretaceous inversion tectonics in the Danish Central Graben – regionally synchronous tectonic events? Bulletin of the Geological Society of Denmark, Vol. 49, pp. 129–144. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-11
Abstract:Structural analysis of the Upper Cretaceous to Palaeogene succession in the Danish Central Graben suggests continuous inversion heralded in the Late Hauterivian and continuing into Palaeogene times. The following phases of increased intensity are identified: 1) latest Santonian, 2) Mid Campanian, 3) late Maastrichtian, 4) Late Paleocene – Eocene, and 5) Early Oligocene. Phases 1 through 3 are Sub-Hercynian, phase 4 is Laramide, and phase 5 is Pyrenean according to Alpine Orogen nomenclature. A temporal change in structural style is noted from early inversion confined to narrow zones associated with reverse faulting along pre-existing normal faults to late inversion dominated by gentle basinwide flexuring and folding. Inversion phases in the Danish Central Graben seem to be synchronous with inversion phases along the Sorgenfrei-Tornquist Zone. The location of inversion is generally spatially linked to Upper Jurassic – Lower Cretaceous depocentres, whereas older depocentres generally have remained intact. The origin of the compressional stress field is generally based on suggested compressional stresses transmitted into the foreland from the Alpine Orogen. In the Sub-Hercynian phase, orogenic compression dominated the Eastern Alps and Northern Carpathians to produce a likely NW oriented compression. However, structures in Denmark rather suggest a transpressional environment resulting from NNE–SSW compression. Furthermore, transmission of Alpine orogenic stresses into the foreland commenced in the Turonian, a considerable time after the Late Hauterivian and later inversion precursors. Ridge-push forces transmitted from sea-floor spreading south of the Charlie-Gibbs fracture zone, particularly from the Goban Spur SW of Ireland, acting in conjunction with Alpine orogenic stresses are suggested as the cause for the stress field.
Keywords: Inversion, Central Graben, Upper Cretaceous, Chalk Group, Sorgenfrei-Tornquist Zone.
Addresses:
Ole Valdemar Vejbæk [ ov [at] geus [dot] dk ] & Claus Andersen [ ca [at] geus [dot] dk ], Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen, Denmark. 11 March 2000.
Late Cenozoic palaeogeography of the eastern North Sea Basin: climatic vs tectonic forcing of basin margin uplift and deltaic progradation
Huuse, M. 2002–12–02: Late Cenozoic palaeogeography of the eastern North Sea Basin: climatic vs tectonic forcing of basin margin uplift and deltaic progradation. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 145–170. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-12
Abstract: The late Eocene to middle Pleistocene development of the eastern North Sea Basin is described by a series of palaeogeographic maps. The maps are based on published information integrated with recent investigations of seismic and well data from the eastern North Sea. The maps provide overviews of the basin geometry at late Eocene, late Oligocene, middle Miocene, late Miocene, late Pliocene and middle Pleistocene time. In post-Eocene time, the eastern and central North Sea Basin was progressively filled by large deltas, which built out from the eastern basin margin. These deltas were fed by ancient rivers from southern Norway (late Paleocene-Oligocene and Pliocene), southern Norway and Sweden (early Miocene), the Baltic region (middle Miocene-early Pleistocene), and finally by rivers flowing northward through the northwest European lowland (middle Pleistocene). It is argued that the Cenozoic evolution of the eastern North Sea Basin may be explained by a ‘self-perpetuating’ passive model. This model involves isostatic uplift of source areas due to erosional unloading of a relief generated by early Palaeogene uplift. The erosional unloading accelerated at the Eocene/Oligocene transition, in the middle Miocene and in the Plio-Pleistocene corresponding to periods of global climatic cooling and long-term eustatic lowering as indicated by δ18O records. The passive model diminishes the need for hypothetical Neogene tectonic events, although the influence of tectonic events cannot be excluded. Previous estimates of Neogene uplift and erosion of the northeastern Danish North Sea of the order of 500–1000 m do not agree with seismic geometries or with the regional palaeogeographic development. This indicates that previous estimates of Neogene uplift and erosion of the northeastern Danish North Sea may be several hundred metres too high.
Keywords: Cenozoic, North Sea Basin, Climate, Eustasy, Tectonics.
Addresses:
Mads Huuse [ mhuuse [at] geo [dot] au [dot] dk ], Department of Earth Sciences, University of Aarhus, DK-8000 Århus C, Denmark. 24 March 2000.
Mid-Paleocene palaeogeography of the Danish area
Clausen, O. R. & Huuse, M. 2002–12–02: Mid-Paleocene palaeogeography of the Danish area. Bulletin of the Geological Society of Denmark, Vol. 49, pp. 171–186. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-13
Abstract: At the Danian/Selandian transition the North Sea Basin experienced a marked change, from deposition of almost pure carbonate during the Upper Cretaceous and Danian to deposition of greensand, marl and clay during the Selandian. Erosional features at the Top Chalk surface and the occurrence of an overlying conglomerate (transgressive lag deposit) indicates that large parts of the Danish area were subaerially exposed at the Danian/Selandian transition, probably due to regional tectonic uplift. Tectonically induced inversion of fault trends in the Central Trough and the Sorgenfrei- Tornquist Zone and differential relative subsidence between the Ringkøbing-Fyn High and the Norwegian-Danish Basin strongly affected the distribution of the lower Selandian sediments. Three palaeogeographic maps are presented to illustrate the various stages of the early Selandian transgression in order to demonstrate the mid-Paleocene evolution of the Danish area.
Keywords: Paleocene, Palaeogeography, Denmark.
Addresses:
Ole R. Clausen [ geolorc [at] geo [dot] au [dot] dk ] & Mads Huuse, Department of Earth Sciences, University of Aarhus, DK- 8000 Århus C, Denmark. 6 June 2002.
A post mid-Cretaceous North Sea model
Nielsen, S.B. 2002–12–02: A post mid-Cretaceous North Sea model. Bulletin of the Geological Society of Denmark. Vol. 49, pp. 187–204. Copenhagen.
https://doi.org/10.37570/bgsd-2003-49-14
Abstract: The relative importance and causal relationship between tectonics, eustacy and sediment charge is investigated for the post mid-Cretaceous North Sea. Guided by the predictions of a quantitative model and previously published work it is argued that the geological evolution comprises 1) continued subsidence of the central North Sea and its more marginal basin areas, related to Palaeozoic and Mesozoic lithospheric and deeper processes, 2) Cenozoic uplift of the British Isles (Scotland) and western Fennoscandia initiated by the Iceland plume in Paleocene/Eocene, 3) inversion zone dynamics induced by in-plane stress variations from plate boundary processes (the African-Eurasian collision and Atlantic spreading), and 4) denudation controlled by the availability of topography and erosional base level changes. The processes are consistent with the general present day sediment structure of the North Sea. Furthermore, they produced the pattern and amplitude of the burial anomalies in the North Sea region: 1) the continued subsidence of the central North Sea ensured maximum burial here at the present day, 2) Cenozoic uplift of the coastal areas of Scotland and western Fennoscandia, including southern Norway, produced over-burial that decreases away from the coast with a gradient that depends on the flexural strength of the lithosphere, 3) inversion zones (in particular the Sole Pit High and the Sorgenfrei-Tornquist Zone) developed a two phase burial anomaly, firstly by erosion of the narrow strip of topography in the central zone of inversion, and secondly by more regional erosion of the post-compressional rebound topography, involving both the central inversion zone and the marginal troughs. The falling eustatic level generated a burial anomaly by erosional unloading and isostatic uplift of the basin margins. Deep Quaternary erosion enhanced the burial anomaly in, for example, the Farsund Basin and the Skagerrak. The post-compressional rebound of the Sorgenfrei-Tornquist Zone is identified as the Neogene tectonic mechanism in the eastern North Sea area.
Keywords: modelling, lithosphere, basin inversion, erosion, North Sea basin, Neogene uplift.
Addresses:
Søren B. Nielsen [ sbn [at] geo [dot] au [dot] dk ], Department of Earth Sciences, The University of Aarhus, Finlandsgade 8, DK-8200 Aarhus N, Denmark. 25 November 2002.