GEUS Bulletin (Geological Survey of Denmark and Greenland)
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Jurassic dinoflagellate cyst stratigraphy of Store Koldewey, North-East Greenland
No full textThe Jurassic of Store Koldewey comprises a Middle Jurassic succession towards the south and an Upper Jurassic succession towards the north. Both successions onlap crystalline basement and coarse sediments dominate. Three main lithostratigraphical units are recognised: the Pelion Formation, including the Spath Plateau Member, the Payer Dal Formation and the Bernbjerg Formation. Rich marine macrofaunas include Boreal ammonites and the successions are dated as Late Bathonian – Early Callovian and Late Oxfordian – Early Kimmeridgian on the basis of new collections combined with material in earlier collections. Fine-grained horizons and units have been analysed for dinoflagellate cysts and the stratigraphy of the diverse and well-preserved flora has been integrated with the Boreal ammonite stratigraphy. The dinoflagellate floras correlate with contemporaneous floras from Milne Land, Jameson Land and Hold with Hope farther to the south in East Greenland, and with Peary Land in North Greenland and Svalbard towards the north. The Middle Jurassic flora shows local variations in East Greenland whereas the Upper Jurassic flora gradually changes northwards in East Greenland. A Boreal flora occurs in Peary Land and Svalbard. The characteristic and stratigraphically important species Perisseiasphaeridium pannosum and Oligosphaeridium patulum have their northernmost occurrence on Store Koldewey, whereas Taeniophora iunctispina and Adnatosphaeridium sp. extend as far north as Peary Land. Assemblages of dinoflagellate cysts are used to characterise significant regional flooding events and extensive sequence stratigraphic units
Lower Palaeozoic stratigraphy of the East Greenland Caledonides
No full textThe Lower Palaeozoic stratigraphy of the East Greenland Caledonides, from the fjord region of North-East Greenland northwards to Kronprins Christian Land, is reviewed and a number of new lithostratigraphical units are proposed. The Slottet Formation (new) is a Lower Cambrian quartzite unit, containing Skolithos burrows, that is present in the Målebjerg and Eleonore Sø tectonic windows, in the nunatak region of North-East Greenland. The unit is the source of common and often-reported glacial erratic boulders containing Skolithos that are distributed throughout the fjord region. The Målebjerg Formation (new) overlies the Slottet Formation in the tectonic windows, and comprises limestones and dolostones of assumed Cambrian–Ordovician age. The Lower Palaeozoic succession of the fjord region of East Greenland (dominantly limestones and dolostones) is formally placed in the Kong Oscar Fjord Group (new). Amendments are proposed for several existing units in the Kronprins Christian Land and Lambert Land areas, where they occur in autochthonous, parautochthonous and allochthonous settings
Low-pressure metamorphism during Archaean crustal growth: a low-strain zone in the northern Nagssugtoqidian orogen, West Greenland
No full textOne of the first detailed accounts of Precambrian supracrustal rocks in central West Greenland came from a small group of islands and skerries a few kilometres north-east of Aasiaat (Fig. 1). In 1948, K. Ellitsgaard-Rasmussen spent a few days on the islands and published a metamorphic study of their low-grade greenstones and aluminous clastic rocks (Ellitsgaard-Rasmussen 1954). He observed a striking dissimilarity between these supracrustal rocks and the grey gneisses found in most of the Aasiaat region, although the latter were at that time also assumed to be of supracrustal origin. He furthermore noted that the regional significance of the islands should be pursued, and that the island of Maniitsoq 4 km west of the small islands might hold a key to their interpretation. More than 50 years were to elapse before the islands were surveyed again in July 2003, during field work for the Ikamiut map sheet in the northern Nagssugtoqidian orogen (van Gool et al. 2002). The collision of two Archaean continents during the c. 1850 Ma Nagssugtoqidian orogeny caused intensive structural and thermal reworking at up to granulite facies grade in most of central West Greenland; see Connelly et al. (2000) and van Gool et al. (2002). The small islands north-east of Aasiaat are indeed regionally important, because they document a previously unrecognised low-grade, low-strain domain of presumed Archaean age that has largely escaped the Nagssugtoqidian orogeny, and as predicted by Ellitsgaard-Rasmussen (1954) a clue to their significance was found on Maniitsoq
Jakobshavn Isbræ, West Greenland: the 2002–2003 collapse and nomination for the UNESCO World Heritage List
No full textJakobshavn Isbræ (also known as Sermeq Kujalleq or Ilulissat Isbræ) is situated at about 69°10′N and 50°00′W in West Greenland. This major outlet from the Inland Ice has an extremely high rate of movement (nearly 1 m/hour) and thus a high production of icebergs, which via the icefjord float westwards through Disko Bugt to Davis Strait (Fig. 1). Estimates of the iceberg production are in the range of 35 ± 10 km3 ice per year, more than 10% of the entire calf-ice production of the Inland Ice (e.g. Bauer l968; Bindschadler 1984). The icefjord into which Sermeq Kujalleq calves is Kangia, best known in glaciological literature as Jakobshavn Isfjord. Spectacular changes of the glacier were observed during 2002 and 2003 at the same time as it was nominated for inclusion in the UNESCO World Heritage List under the name ‘Ilulissat Icefjord’
Direct analysis of microbial populations in soil and freshwater aquifers using nucleic acid based techniques
No full textThe first DNA-based methods for direct quantification of soil protozoa, and a DNA-based quantification method to describe the spread of phenanthrene-degrading bacteria in soil and freshwater aquifers, have recently been developed at the BIOPRO Research Centre at the Geological Survey of Denmark and Greenland (GEUS). Well-known genes for phenoxyalcanoic acid degradation have been used to monitor the in situ degradation of phenoxyalcanoic acid pesticides. Studies have been initiated on the short-lived mRNA molecules that are expected to provide a shortcut to the understanding of low, yet important, microbial activity in geological samples. This article reviews recent developments in techniques based on analysis of nucleic acids from soils and aquifers. Analytical work has been carried out mainly on soil samples from a former asphalt production plant at Ringe (Fig. 1). The Ringe plant constitutes one of the most polluted industrial sites in Denmark, and is a priority site of studies by the BIOPRO Research Centre. Although rich in carbon, the Ringe subsoil is an oligotrophic environment due to the high content of polycyclic aromatic hydrocarbons (PAH). This is an environment where the supply of nutrients to microorganisms is low, leading to slow growth, low total numbers of microorganisms and small cells. To study microbial communities of oligotrophic environments, analytical methods with low detection limits are needed. Until recently, microorganisms of natural environments were mainly studied by cultivation-dependent methods. However, microorganisms that can be cultured on agar plates are now known to represent only a small fraction of the total microbial community. Modern methods, therefore, need to be based on the detection of biomolecules in the microorganisms rather than being dependent on growth of the microorganisms. The best available techniques are based on DNA and RNA molecules (Fig. 2), which due to their high level of resolution allow closely related organisms or functional genes to be distinguished. In the following review, examples are given of applications of these nucleic acid based methods
Co-operation with the Geological Survey Department of Ghana
No full textBetween October 2001 and the end of 2003 there was a close co-operation between the Geological Survey of Denmark and Greenland (GEUS) and the Geological Survey Department of Ghana (GSD), as part of a project to enhance GSD’s institutional capabilities and effectiveness, mainly in the fields of management, geological mapping, map production and data handling. During this period a team of geologists, GIS (Geographic Information System) and database experts as well as administrative staff from GEUS have visited GSD, and GSD officers have visited GEUS in Copenhagen. The main obstacles to GSD becoming an effective organisation are its status as a department under the Ghana Ministry of Mines, insufficient funding by the government, and poor remuneration of its professional staff. To overcome these obstacles, attempts are being made to change the status of GSD from a ‘civil servant organisation’ into a semiautonomous institution, which will permit the Survey to generate funding for its core activities by providing services to outside organisations, and pay better salaries to its personnel. Despite many problems, geological mapping has been resumed and three new geological maps have been produced by GSD during the project and stored in GIS format. A mapping manual has been prepared, and the structure and ‘Mission and Vision Statements’ for the Survey have been revised
A new Middle–Upper Jurassic succession on Hold with Hope, North-East Greenland
No full textA succession of marine, Jurassic sediments was recently discovered on Hold with Hope, North-East Greenland. The discovery shows that the area was covered by the sea during Middle–Late Jurassic transgressive events and thus adds to the understanding of the palaeogeography of the area. The Jurassic succession on northern Hold with Hope is exposed in the hangingwalls of small fault blocks formed by rifting in Late Jurassic – Early Cretaceous times. It unconformably overlies Lower Triassic siltstones and sandstones and is overlain by Lower Cretaceous coarse-grained sandstones with an angular unconformity. The succession is up to 360 m thick and includes sandstones of the Lower–Upper Callovian Pelion and Middle–Upper Oxfordian Payer Dal Formations (Vardekløft Group) and heteroliths and mudstones of the Upper Oxfordian – Lower Kimmeridgian Bernbjerg Formation (Hall Bredning Group). The Pelion Formation includes the new Spath Plateau Member (defined herein). The palaeogeographic setting was a narrow rift-controlled embayment along the western margin of the rifted Jurassic seaway between Greenland and Norway. It was open to marine circulation to the south as indicated by the distribution and lateral facies variations and a dominant south-westwards marine palaeocurrent direction. The Pelion and Payer Dal Formations represent upper shoreface and tidally influenced delta deposits formed by the migration of dunes in distributary channels and mouthbars over the delta front. The boundary between the two formations is unconformable and represents a Late Callovian – Middle Oxfordian hiatus. It is interpreted to have formed by subaerial erosion related to a sea-level fall combined with minor tilting of fault blocks and erosion of uplifted block crests. In Late Jurassic time, the sand-rich depositional systems of the Pelion and Payer Dal Formations drowned and offshore transition – lower shoreface heteroliths and offshore mudstones of the Bernbjerg Formation accumulated. The fault block crest forming the eastern basin margin was inundated by a rise in relative sea level. Major fault activity probably occurred in latest Jurassic – Early Cretaceous times when the major fault block originally defining the Hold with Hope basin was split into smaller blocks
Colophon, content and preface
No full textThe East Greenland Caledonides extend from 70° to 81°30′N, and have been the subject of a series of regional mapping programmes between 1968 and 1998. The entire orogen is now covered by five published 1:500 000 geological map sheets. The six papers in this bulletin concern a variety of topics relating mainly to Kronprins Christian Land (79°–81°30′N) and the Kong Oscar Fjord region (72°–75°N). The paper by Smith et al. on Lower Palaeozoic stratigraphy proposes amendments to several stratigraphical units that occur in Kronprins Christian Land and nearby Lambert Land. In the Kong Oscar Fjord region, two new formations are defined for quartzite and limestone/dolostone units that crop out in foreland windows, and the Lower Palaeozoic succession of the fjord region of East Greenland is formally placed in the Kong Oscar Fjord Group. The second paper by Smith et al. describes and formally defines the Neoproterozoic Rivieradal Group of Kronprins Christian Land. The paper by Higgins et al. analyses the thinskinned fold-and-thrust belt that marks the transition between foreland and orogen in Kronprins Christian Land, and presents a balanced cross-section restoration. The two geochronological papers by Thrane report the results of ion microprobe zircon analyses from orthogneisses in the Charcot Land window (72°N), and results of reconnaissance Pb-Pb dating by the stepleaching method.The final paper by Higgins & Leslie reviews the history of geological research in the Eleonore Sø and Målebjerg areas of the Kong Oscar Fjord region (72°–75°N). Recognition that the two areas are part of the Caledonian foreland implies that the two thrust sheets structurally overlying the Eleonore Sø and Målebjerg windows have large displacements (~ 100 km each), and that the \u27stockwerke\u27 concept of the orogen that focused on in situ vertical movements can finally be laid to rest
