GEUS Bulletin (Geological Survey of Denmark and Greenland)
Not a member yet
521 research outputs found
Sort by
The ammonites of the Middle Jurassic Cranocephalites beds of East Greenland
No full textThick successions of marine Middle Jurassic deposits rich in ammonites occur in the Jameson Land Basin in central East Greenland. The fauna of the so-called Cranocephalites beds of this basin, comprising the Borealis–Pompeckji Standard Zones, was until now largely represented by a single collection. This was made by T.M. Harris during a 1927 excursion up the valley of Ugleelv to Katedralen, the type area of Cranocephalites pompeckji, which is the oldest named species of this genus. Revisits to this area in 1994 and 1996 by JHC resulted in a large bed-by-bed collection of Cranocephalites. The number of faunal horizons that could be distinguished grew from the nine previously recognised to thirty-four today. The zonal stratigraphy of the Cranocephalites beds encompasses the Borealis, Indistinctus and Pompeckji Standard Zones. The Pompeckji Zone is subdivided into four new subzones, reflecting four successive basic morphologies of Cranocephalites that should be recognisable more widely and are thus useful for subzonal correlations. The detailed zonation that serves as the secondary standard zonation for the Boreal Province in the Middle Jurassic is thus highly improved. The biostratigraphic resolution obtained here is near the achievable limits. It allows a high-resolution study of the evolution of the ammonites which on this timescale appears to be continuous. Three new species are described: Cranocephalites carolae sp. nov., Cranocephalites intermissus sp. nov. and Cranocephalites episcopalis sp. nov. An additional new species, Cranocephalites tvaerdalensis sp. nov., is described in the appendix by P. Alsen based on collections from Tværdal on Geographical Society Ø, North-East Greenland. This species is also recorded in Jameson Land
Acoustic events on a small seismological network – shock waves from thunder and fireballs
No full textThe Geological Survey of Denmark and Greenland (GEUS) operates a network of seismic stations in Denmark primarily to detect earthquakes. But from time to time other sources than earthquakes generate seismic signals that are detected at the stations. Here we show that both meteoroids and thunder have generated seismic signals with high signal-to-noise ratios at some of GEUS’ seismic stations (Fig. 1). The purpose of the seismic stations is to provide data for the earthquake database of the Kingdom of Denmark, hosted and maintained by GEUS. In order to avoid that the earthquake database is contaminated by other events not related to tectonism, these events are given special markers when possible
The Lower Palaeozoic shale gas play in Denmark
No full textThe unconventional gas resources in the Lower Palaeozoic shale of Denmark were recently assessed by the United States Geological Survey (USGS; Gautier et al. 2013). Assuming unrestricted application of best practice current technology, recoverable gas resources of 0 to 130 × 109 Nm3 gas were estimated onshore (mean = 67 × 109 Nm3 gas) and 0 to 228 × 109 Nm3 gas were estimated offshore (mean = 119 × 109 Nm3 gas), i.e. a total estimated mean of 186 × 109 Nm3 gas (Nm3: normal cubic metre, unit used for natural gas at 0°C and 101.325 kPa). Nearly all of this potential resource is assumed to be contained in the Cambro-Ordovician Alum Shale. The wide range of estimates reflects the sparse data and the geological uncertainty inherent in the still untested play. The estimated mean quantity of gas resource is comparable to the total volume of gas produced from the Danish part of the North Sea during 1972–2011 and twice the amount of the estimated remaining reserves of conventional gas in the Danish part of the North Sea
Arctic plant remains of Weichselian age from the Danish North Sea
No full textThe North Sea is a large, shallow epicontinental sea dominated by a sandy bottom that reflects a high-energy environment. Little is known about the environmental history of the Danish part of this large area during the Weichselian, the last ice age. Parts of it were glaciated during the last glacial maximum and probably also during older glaciations. Shallow parts were dry land, and deeper parts were covered by the sea during ice-free intervals. Large, partly ice-dammed lakes also existed
Integrating 3D photogeology with aeromagnetic data as a tool for base-metal exploration in East Greenland
No full textAn 800 km long basin system developed along the East Greenland margin since the Late Palaeozoic in which the Jameson Land Basin forms the southern part of the system. Along the margins of the Jameson Land Basin there are occurrences of barite, copper, lead, zinc and silver, which are particularly abundant in the northern part of the basin’s eastern margin in the Wegener Halvø area (Fig. 1). Structures and stratigraphic architecture play important roles in the mineralisation distribution, so detailed mapping is essential. We used 3D photogeology combined with geophysical data to map the different stratigraphic units, faults and dykes in three dimensions
Outlet glacier dynamics and bathymetry at Upernavik Isstrøm and Upernavik Isfjord, North-West Greenland
No full textDuring the past decades, the Greenland ice sheet has experienced a marked increase in mass loss resulting in an increased contribution to global sea-level rise. The three largest outlet glaciers in Greenland have increased their discharge, accelerated, thinned and retreated between 1996 and 2005. After 2005 most of them have slowed down again although not to previous levels. Geodetic observations suggest that rapid increase in mass loss from the north-western part of the ice sheet occurred during 2005–2010 (Kjeldsen et al. 2013)
Ribbed moraines formed during the retreat of the Scandinavian ice sheet from eastern Himmerland, NE Jylland, Denmark
No full textThe glacial geology of Himmerland in the north-eastern part of Jylland, south of Limfjorden (Fig. 1) has never received any special attention. However, the occurrence of parallel ridges south of Torup was mentioned by Milthers (1948) who interpreted them as marginal moraines. The ridges were recently studied during mapping of eastern Himmerland. Systematic geological mapping of the area north and south of Mariager Fjord started in 2009 and was completed in 2013 (map sheet 1316 III; Pedersen et al. 2013). This was followed by the map sheet to the north (1316 IV). During the recent mapping the extent of the terrain with parallel ridges was determined (Fig. 2); the western boundary is found in Rold Skov (Pedersen & Jakobsen 2005) and the eastern boundary follows an ancient coastline in eastern Himmerland. The most impressive parallel ridges occur in a forested area east of Madum Sø where the top level of the ridge crests reaches an elevation of 95 m a.s.l. However, the majority of the crests are at 60–70 m a.s.l. and most of the ridges are c. 10–15 m high. The sediments in the ridges are dominated by coarse-grained sand and gravel, and accumulations of erratic boulders are found on the surface of the ridges
Estimating thermal conductivity from lithological descriptions – a new web-based tool for planning of ground-source heating and cooling
No full textIt is the overall policy of the Danish Government that by 2050 electricity, heating and transport will be 100% based on renewable energy. In order to reach this goal a number of different green technologies will have to interact. In areas with no district heating, ground-source heating by heat pump technology (Sanner 2011) could well be one of the solutions
Earthquake swarms in Greenland
No full textTwo earthquake swarms have been detected in Greenland. One occurred on the island of Disko in August 2010, the other one was active from January 2008 to June 2009 near the South-East Greenland coast c. 200 km south of Tasiilaq. An earthquake swarm is defined as a series of earthquakes of similar magnitude located within a small area. The magnitude of the largest earthquakes in a swarm is typically less than 4 (Ma & Eaton 2009). Swarm activity is distinctly different from the more common mainshock–aftershock activity, which is characterised by one large earthquake (mainshock) followed by a series of smaller aftershocks. Earthquake swarms mainly occur in areas with tectonic and/or volcanic activity (Stykes 1970), but intraplate swarms are also found in otherwise stable environments (Gregersen 1979; Atakan et al. 1994; Uski et al. 2006; Ma & Eaton 2009). Geological boundaries and old fault zones appear to be a common setting for intraplate earthquake swarms. Earthquake swarms have previously been detected in North and North-East Greenland (Gregersen 1979) at a time when the seismograph coverage was very sparse. It was concluded that the earthquake swarms were caused by tectonic stresses in and around old sedimentary basins near the continental margin
125 years of geological research for society
No full textIn 1888 the first geological survey in the Kingdom of Denmark was born as the Geological Survey of Denmark (DGU, Danmarks Geologiske Undersøgelse) and in 1946 the Geological Survey of Greenland (GGU, Grønlands Geologiske Undersøgelse) was established. Both surveys were located in Copenhagen and were amalgamated in 1995 to form the Geological Survey of Denmark and Greenland (GEUS)