Contents of Volume 47/1
Garde, A.A., Friend, C.R.L., Nutman, A.P. & Marker, M.:
Rapid maturation and stabilisation of middle Archaean continental crust: the Akia terrane, southern West Greenland
Bruton, D.L. & Harper, D.A.T.:
A mid-Cambrian shelly fauna from Ritland, western Norway and its palaeogeographical implications .
Schovsbo, N.H.:
Environmental fluctuations in the Olenus Zone (Upper Cambrian), southern Scandinavia: A geochemical approach
Hansen, T. & Hansen, J.:
The echinoid Brissopsis lyrifera from the Danish Upper Miocene Gram Formation
Konradi, P.B.:
Biostratigraphy and environment of the Holocene marine transgression in the Heligoland Channel, North Sea .
Christensen, W.K., Hancock, J.M., Peake, N.B. & Kennedy, W.J.:
The base of the Maastrichtian
Dybkjær, K. & Rasmussen, E.S.:
Palynological dating of the Oligocene – Miocene successions in the Lille Bælt area, Denmark
Book review
Landvik, J.Y.: Molluscs and the formation of the Arctic
Editor’s Column Christensen, W.K.: Change in Bulletin format
Contents of Volume 47/2
Rees, J.
An Early Creataceous scincomorph lizard dentary from Bornholm, Denmark
Bennike, O., Björck, S., Böcher, J. & Walker, I.R. :
The Quaternary arthropod fauna of Greenland: a review with new data.
Christensen, W.K. :
Gradualistic evolution in Belemnitella from the middle Campanian of Lower Saxony, NW Germany
Rapid maturation and stabilisation of middle Archaean continental crust: the Akia terrane, southern West Greenland
Garde, Adam A., Friend, R.L., Nutman, A.P. & Marker, M. 2000: Rapid maturation and stabilisation of middle Archaean continental crust: the Akia terrane, southern West Greenland. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 1–27, Copenhagen.
https://doi.org/10.37570/bgsd-2000-47-01
Abstract: from the Akia terrane, southern West Greenland, supported by Sm-Nd isotope geochemistry, document its middle Archaean accretional history and provide new evidence about the location of its northern boundary. Zircon populations in grey gneiss and inherited zircons in granite show that magmatic accretion of new continental crust, dominated by intrusion of tonalite sheets in a convergent island arc setting, occurred between c. 3050 and 3000 Ma, around and within a c. 3220 Ma continental core. In the central part of the terrane, tonalite sheets were intercalated with older supracrustal rocks of oceanic affinity by intrusion, thrusting and folding during the Midterhøj and Smalledal deformation phases of Berthelsen (1960). Continued tonalite injection led to a thermal maximum with granulite facies conditions at c. 2980 Ma, dated by metamorphic zircons in grey gneiss. The metamorphic maximum was contemporaneous with upright, angular folds of the Pâkitsoq deformation phase. Within a few million years followed high-grade retrogression and intrusion of two large dome-shaped tonalite-granodiorite complexes, granites s.l. derived from remobilisation of grey gneiss, and post-kinematic diorite plugs. Whereas the relative chronology of these events is firmly established from field observations, zircons from the post-granulite facies intrusions all yielded statistically indistinguishable emplacement ages of c. 2975 Ma. These results show that crustal growth occurred in several short-lived events starting at c. 3220 Ma, and that final maturation and stabilisation of new, thick continental crust took place rapidly (within c. 20 Ma) at c. 2975 Ma.
Keywords: Archaean, southern West Greenland, Akia terrane, continental crust, deformation, granulite facies, zircon, ion probe, U-Pb, Sm-Nd..
Addresses:
A.A. Garde, Geological Survey of Denmark and Greenland, Thoravej 8, 2400 Copenhagen NV, Denmark. C.R.L. Friend, Department of Geology, Oxford Brookes University, Headington, Oxford, Oxon OX3 0BP, UK. A.P. Nutman, Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia. M.Marker, Norges Geologiske Undersøkelse, Leiv Eirikssons Vei 39, Postboks 3006 - Lade, 7002 Trondheim, Norge. 13 April 1999.0.
A mid-Cambrian shelly fauna from Ritland, western Norway and its palaeogeographical implications
Bruton, D.L. & Harper, D.A.T. 2000: A mid-Cambrian shelly fauna from Ritland, western Norway and its palaeogeographical implications. Bulletin of the Geological Society of Denmark 47, pp. 29–51. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-02
Abstract: A new mid-Cambrian shelly fauna from Ritland, western Norway, significantly extends the known development of the Andrarum limestone facies to the edge of the Baltic craton. The assemblage includes the trilobitesAxagnostus fallax (Linnarsson), Solenopleura bucculenta Grönwall, Anomocare cf. laeve (Angelin) and abundant, etched specimens of the linguliformean brachiopod Treptotreta? socialis (von Seebach) together withDictyonina ornatella (Linnarsson); the fauna indicates the presence of the Jincella brachymetopa Zone and also includes hyoliths, bradoriid crustaceans and sponge spicules. Elsewhere the trilobites and brachiopods have widespread distributions in amphicratonic settings during this part of the mid-Cambrian; the Scandinavian faunas signal the inshore migration of these more cosmopolitan elements, tracking the shallower-water development of calcareous facies of the Andrarum Limestone.
Keywords: Trilobites, brachiopods, facies, Cambrian, Norway.
Addresses:
David L. Bruton [ d [dot] l [dot] bruton [at] toyen [dot] uio [dot] no ], Paleontologisk Museum, Sars gate 1, Oslo, Norway; David A.T. Harper [ dharper [at] savik [dot] geomus [dot] ku [dot] dk ], Geologisk Museum, Øster Voldgade 5-7, DK-1350 Copenhagen, Denmark. 4 April 2000.0.
Environmental fluctuations in the Olenus Zone (Upper Cambrian), southern Scandinavia: A geochemical approach
Schovsbo, N.H. 2000: Environmental fluctuations in the Olenus Zone (Upper Cambrian), southern Scandinavia: A geochemical approach. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 53–61. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-03
Abstract: The Scandinavian Alum Shale Formation (Middle Cambrian to Lower Ordovician) was deposited under generally low bottom water oxygen levels. In the formation there is a covariance between faunal composition and the level of trace element enrichment caused by their mutual dependence upon changes in the bottom water oxygen levels. A detailed profile of the V/(V+Ni) ratio through the Upper Cambrian Olenus Zone in the Gislövshammar-2 core, Scania, Sweden, is described. Environmental information from this zone is particularly relevant since the Olenus species in the zone apparently undergo iterative changes in morphology that may be linked to environmental changes. Moreover, the occurrences of Olenus species and Homagnostus obesus are almost mutually exclusive. The results indicate that the trilobitic intervals coincide with increases in oxygen levels as monitored by the V/(V+Ni) ratio. Peak oxygen levels do not appear at the base of each interval, suggesting that colonisation of the sea-floor took place when the oxygenation level reached a certain threshold but before maximum oxygen levels were reached. The distribution patterns of Olenus and Homagnostus are interpreted as reflecting differences in substrate preference since samples containing Homagnostus have statistically significantly higher TOC levels. The V/(V+Ni) variations in the Olenus bearing intervals suggest that oxygen levels fluctuated more than would be expected from morphological changes apparent in the Olenusspecies.
Keywords: Alum Shale, Gislövshammar-2, olenids, agnostids, evolution, dysoxic, substrate, V/(V+Ni).
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. 3 May 2000.
The echinoid Brissopsis lyrifera from the Danish Upper Miocene Gram Formation
Hansen, T. & Hansen, J. 2000: The echinoid Brissopsis lyrifera from the Danish Upper Miocene Gram Formation. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 63–69. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-04
Abstract: The irregular echinoid Brissopsis is described for the first time from the type locality of the Upper Miocene Gram Formation at Gram, Denmark. The specimens are conspecific with the Recent Brissopsis lyrifera Forbes, 1841. Futhermore they show remarkable resemblance to the Danish forms of B. lyrifera.
Keywords: Brissopsis lyrifera, Upper Miocene, Gram Formation, Denmark.
Addresses:
Thomas Hansen & Jesper Hansen, Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen, Denmark. 1 June 1999.
Biostratigraphy and environment of the Holocene marine transgression in the Heligoland Channel, North Sea
Konradi, P.B. 2000: Biostratigraphy and environment of the Holocene marine transgression in the Heligoland Channel, North Sea. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 71–79. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-05
Abstract: A 51 m deep borehole in the outer Heligoland Channel, south-eastern North Sea, penetrated 17 m of marine Holocene, laminated, clayey silt and silty fine sand followed by 34 m of Pleistocene, fluvial sand. Samples from the two units were investigated for their content of foraminifers. The fluvial sand yielded only reworked foraminifers and, based on these is divided into two parts that can be related to differences in lithology. Based on the study of the foraminiferal assemblages in 20 samples, the marine unit is divided in five foraminiferal assemblage zones reflecting the marine inundation into this part of the North Sea after the last glaciation. The basal part of the unit is strongly influenced by freshwater and the lowermost part is dated to c. 11.0 cal. ka BP. The freshwater influence diminishes uphole with deposition of beds characteristic of a tidal flat environment in an estuarine setting with slowly increasing sedimentation depth. A subsequent sudden change in the fauna indicating higher salinity and a more open-marine environment is interpreted to reflect a change in the hydrographic situation. The basal part of this zone is dated to c. 8.6 cal. ka BP. A continuation of this trend is observed in the following zones with further increasing sedimentation depth. The fauna in the topmost assemblage zone indicates an environment comparable to the present conditions in this area of the North Sea.
Keywords: Foraminifera, biostratigraphy, environment, radiocarbon dating, sea level, Quaternary, Holocene, North Sea
Addresses:
Peter B. Konradi [ pk [at] geus [dot] dk ], Geological Survey of Denmark and Greenland, Thoravej 8, DK-2400 Copenhagen NV, Denmark. 10 March 2000.
The base of the Maastrichtian
Christensen, W.K., Hancock, J.M., Peake, N.B. & Kennedy, W.J. 2000: The base of the Maastrichtian. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 81–85, Copenhagen. https://doi.org/10.37570/bgsd-2000-47-06
Abstract: At the Brussels Symposium on Cretaceous Stage Boundaries in 1995, the Maastrichtian Working Group decided to recommend the first occurrence of the ammonite Pachydiscus neubergicus in the Tercis quarry near Dax in the Landes, southwest France as the boundary stratotype for the base of the Maastrichtian stage. On the basis of the echinoid genus Echinocorys the Campanian-Maastrichtian boundary beds of Tercis are correlated with the succession in north Norfolk, England, which in turn is correlated with the succession at Kronsmoor, northwest Germany on the basis of belemnites and brachiopods. If the possible correlation between Tercis and northwest Germany is true, the P. neubergicus and Belemnella lanceolata standards for the base of the Maastrichtian stage are not separated by more than 0.2 m.y.
Keywords: Maastrichtian stage, base, Tercis, SW France, correlations.
Addresses:
Walter Kegel Christensen [ wkc [at] savik [dot] geomus [dot] ku [dot] dk ], Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen, Denmark. Jake M. Hancock [ j [dot] hancock [at] ic [dot] ac [dot] uk ], T.H. Huxley School, Imperial College, Prince Consort Road, London SW7 2BP, U.K. Norman B. Peake, 30 St. Benedict’s Street, Norwich NR2 4AQ, U.K. William James Kennedy [ jim [dot] kennedy [at] earth [dot] ox [dot] ac [dot] uk ], Geological Collections, Oxford University Museum, Parks Road, Oxford OX1 3PW, U.K. 11 August 2000.
Palynological dating of the Oligocene – Miocene successions in the Lille Bælt area, Denmark
Dybkjær, K. & Rasmussen, E.S. 2000: Palynological dating of the Oligocene – Miocene successions in the Lille Bælt area, Denmark. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 87–103, Copenhagen. https://doi.org/10.37570/bgsd-2000-47-07
Abstract: A new geological model for the succession outcropping in the Lille Bælt area, Denmark, is proposed. The model is based on dinoflagellate cyst stratigraphy on the three sections at Hindsgavl, Hagenør and Rønshoved combined with earlier biostratigraphic studies and sequence stratigraphic correlation of outcrops and borings.
Our results indicate that there have been two periods with lagoonal and nearshore marine deposition in the Lille Bælt area separated by a hiatus of at least 3.5 million years. The first period occurred in Late Oligocene or earliest Early Miocene (early Aquitanian) time and is represented by the deposits at Hindsgavl. The second period occurred in Early Miocene (early to mid-Burdigalian) time and is represented by the deposits at Hagenør and Rønshoved.
The deposits at Hindsgavl are time equivalent with the lagoonal upper part of the Vejle Fjord Formation and the overlying nearshore marine sand at Hvidbjerg. The deposits at Hagenør and Rønshoved correlate with the lower part of the offshore marine Arnum Formation and thus represent part of the coastline during the early to mid-Burdigalian.
Keywords: Palynology, sequence stratigraphy, Late Oligocene, Early Miocene, Hagenør, Hindsgavl, Rønshoved, Lille Bælt, Denmark.
Addresses:
Karen Dybkjær [ kd [at] geus [dot] dk ] & Erik Skovbjerg Rasmussen [ esr [at] geus [dot] dk ], Geological Survey of Denmark and Greenland (GEUS), Thoravej 8, DK-2400 Copenhagen NV, Denmark. 3 April 2000.
An Early Cretaceous scincomorph lizard dentary from Bornholm, Denmark
Rees, J.: An Early Cretaceous scincomorph lizard dentary from Bornholm, Denmark. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 105–109. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-08
Abstract: A single dentary of a terrestrial lizard was recently discovered in the lowermost part of the Early Cretaceous Jydegård Formation on the island of Bornholm, Denmark. The general outline of the dentary, including a large, partly open Meckelian groove, a coronoid process and a fairly large subdental shelf, in combination with the lack of an intramandibular septum, strongly indicate scincomorph affinity. Further identification is at present not possible as there are a limited number of characters preserved on the dentary. This is the first terrestrial Mesozoic lizard recorded from Scandinavia.
Keywords: Lizard, dentary, Scincomorpha, Early Cretaceous, Bornholm, Denmark.
The Quaternary arthropod fauna of Greenland: a review with new data
Bennike, O., Björck, S., Böcher, J. & Walker, I. R.: The Quaternary arthropod fauna of Greenland: a review with new data. Bulletin of the Geological Society of Denmark, Vol. 47, pp. 111–134. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-09
Abstract: Arthropod fossils from Quaternary deposits in Greenland are considered. The few occurrences of Early and Middle Pleistocene age have yielded only three species of barnacles. This contrasts sharply with the last interglacial stage which is represented by many sites, from which a range of marine, lacustrine and terrestrial crustaceans and insects are reported. The only secure late glacial sediments from Greenland are found in the far south, and only a few taxa of arthropods have so far been identified from these. The best dated and richest faunas come from the Holocene. Most records of insects are from the late Holocene, but there are also a number of finds from the early and mid Holocene. Arthropods are considered good palaeoclimate indicators, because they are generally dispersed quicker, for example, than vascular plants. This group of animals is also highly useful for reconstructing former ecological conditions, because they occupy such a wide range of biotopes. A total of about 105 taxa have been reported so far, but several groups of arthropods, such as marine ostracodes, chironomids and oribatids, have received little attention, and many more taxa can be expected when these groups are being studied in the future.
Keywords: Greenland, Quaternary, biogeography, palaeoecology, Arthropoda, Insecta, Crustacea, Cladocera, Ostracoda.
Addresses:
O. Bennike [ obe [at] geus [dot] dk ], Geological Survey of Denmark and Greenland, Thoravej 8, DK-2400 Copenhagen NV, Denmark. S. Björck, Department of Quaternary Geology, Lund University, Tornavägen 13, SE-223 63 Lund, Sweden. J. Böcher, Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark. I. R. Walker, Departments of Biology, and Earth & Environmental Sciences, Okanagan University College, 3333 College Way, Kelowna, British Columbia, Canada V1V 1V7. 28 April 2000.
Gradualistic evolution in Belemnitella from the middle Campanian of Lower Saxony, NW Germany
Christensen, W.K.: Gradualistic evolution in Belemnitella from the middle Campanian of Lower Saxony, NW Germany. Bulletin of the Geological Society of Denmark 47, 135–163. Copenhagen. https://doi.org/10.37570/bgsd-2000-47-10
Abstract: Nine samples of the Belemnitella lineage, including the uppermost Lower and lower Upper Campanian B. mucronata and the uppermost lower Upper Campanian B. misburgensis sp. nov., from the expanded uppermost Lower and lower Upper Campanian succession of the Lehrte West Synclinee east of Hannover, Lower Saxony, northern Germany have been subjected to univariate and bivariate statistical analyses. The succession consists of monotonous marly limestones and calcareous marls, which were deposited during 4–5 m.y. in a fairly stable environment. Based on superficial resemblance alone the nine samples are nearly identical, but trends have been recognized in the morphological characters when treated quantitatively. Three characters, the length from the apex to the protoconch, the slenderness of the guard and the alveolar angle, show evolutionary reversals (socalled zig-zag evolution) with net decreases or increases. The Schatzky distance shows stasis in B. mucronata and decreases in B. misburgensis sp. nov. The fissure angle displays unidirectional evolution and increases gradually. These morphological changes are interpreted as long term phyletic gradualism, although this model of evolution has almost universally been depicted as one of unidirectional change. B. misburgensis sp. nov. is closely allied to B. mucronata (its ancestor), but differs in its slightly smaller and more slender guard, in addition to its smaller Schatzky distance and larger fissure angle. B. praecursor is recorded from the uppermost five metres of the Lower Campanian, and this is the first record of this species from the highest Lower Campanian of northern Germany. The uppermost Lower and Lower Upper Campanian belemnite assemblages of the Misburg/Höver area in northern Germany are reviewed. The Upper Campanian Belemnitella successions of Norfolk in England, the Maastricht-Liège district in The Netherlands and Belgium, the Mons Basin in southern Belgium, Scania in southern Sweden and the Misburg-Höver area in northwest Germany are compared and contrasted.
Keywords: Belemnites, Belemnitella praecursor, B. mucronata, B. misburgensis sp. nov., Campanian, Lehrte West Syncline, Lower Saxony, northwest Germany, biometry, gradualistic evolution, Upper Campanian Belemnitella successions.
Addresses:
Walter Kegel Christensen [ wkc [at] savik [dot] geomus [dot] ku [dot] dk ], Geological Museum, University of Copenhagen, Øster Voldgade 5–7, DK-1350-Copenhagen, Denmark. 11 September 2000.
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