GEUS Bulletin (Geological Survey of Denmark and Greenland)
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A digital, spatial, geological model of the Miocene in Jylland, Denmark
No full textA major hydrogeological programme has been carried out to map the Miocene succession in central and southern Jylland (Fig. 1). The Miocene deposits comprise several aquifers with potential drinking water resources and have been investigated by drilling and acquisition of seismic data integrated with sedimentology and biostratigraphy. Scharling et al. (2009) described a 3D hydrogeological model that covers part of the onshore Danish Miocene deposits. The model was based on a sequence-stratigraphic approach and led to a better understanding of the geological architecture of the aquifers than traditional lithofacies models. Hence it was decided to establish a digital, spatial, geological model covering the entire onshore Miocene succession (Kristensen et al. 2010)
Postglacial, relative shore-level changes in Lillebælt, Denmark
No full textThe brackish Baltic Sea and the more saline Kattegat are connected by three straits, Lillebælt, Storebælt and Øresund (Fig. 1). Of the three straits, Lillebælt is the narrowest, with 700 m at its narrowest point, widening out towards the south to around 25 km (Fig. 2). In the narrow parts of Lillebælt, water depths around 30–50 m are common. In the northern part of Lillebælt the depth is 16–18 m and in the southern part the depth is around 35 m. Storebælt and Øresund have played important roles as outlets during the history of the Baltic Sea, and their histories have been much discussed (Björck 1995; Bennike et al. 2004). In contrast, Lillebælt has received little attention. In this paper we present 11 new radiocarbon accelerator mass spectrometry (AMS) ages and propose a curve for Holocene relative shore-level changes in Lillebælt. We use the term shore-level changes rather than sea-level changes because we have constructed both lake-level and sea-level changes
Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea
No full textThe 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or absence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four different turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are represented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total) are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in slumping. The vertical succession of facies records an earliest Cenomanian facies shift from dominantly siliciclastic to chalk deposition. The Cenomanian – late Campanian period was dominated by erosion or sediment by-pass with minor associated mass-transport deposits preserved. Basin filling by pelagites and turbidites prevailed in the late Campanian, whereas Maastrichtian pelagic deposition was interrupted by increasingly frequent and voluminous mass-transport events
DODEX – Geoscience Documents and Data for Exploration in Greenland
No full textIn the following we describe the project Geoscience Documents and Data for Exploration in Greenland, in short DODEX. A central part of DODEX is an interactive web application (http://www.geus.dk/dodex/) that provides easy access to all non-confidential company geoscience reports received by the authorities in Greenland and Denmark in accordance with the Mineral Resources Act of Greenland (1 January 2010) and associated regulations. From the web application it is possible to search in the DODEX report database using alphanumeric and geographic search criteria and to access report metadata. It is also possible to download the actual report as a PDF file. In addition to the open DODEX web application, the project also includes the development of a closed web application where authorised users can access confidential reports. The DODEX project was carried out at the Geological Survey of Denmark and Greenland (GEUS) in cooperation with the Bureau of Minerals and Petroleum (BMP) under the Government of Greenland as part of the promotion of the mineral resources of Greenland
Programme for Monitoring of the Greenland Ice Sheet (PROMICE): first temperature and ablation records
No full textThe Greenland ice sheet is reacting to climate change. Yet, mass-budget estimates differ considerably, partly due to climatic variability and partly to uncertainties in the techniques of assessing mass change (IPCC 2007). Nevertheless, all recent estimates agree that the ice sheet is losing mass (e.g. 286 Gt/yr; Velicogna 2009) at an accelerating rate (Rignot et al. 2011). On top of this, the area with a negative mass budget is expanding rapidly (Khan et al. 2010). The mass loss is attributed equally to increases in both iceberg production and melting of the ice sheet (Van den Broeke et al. 2009). The increasing mass loss in recent years has caught public attention and given rise to concern worldwide due to its potential impact on sea level. In the light of this, the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) was initiated in 2007 (Ahlstrøm & PROMICE project team 2008), lead by the Geological Survey of Denmark and Greenland (GEUS). PROMICE undertakes surface mass-budget measurements using automatic weather stations, quantifies the mass loss by iceberg calving using remotely sensed data from satellites and airborne surveys and tracks changes in the extent of glaciers. In this paper, we focus on weather station measurements, which are crucial in calculating the energy exchange between the atmosphere and the ice sheet, and in validating model calculations of the surface mass budget. In particular, we present the observed temperatures and investigate how their high 2010 values affected ablation in southern Greenlan
Mapping of raw materials and habitats in the Danish sector of the North Sea
No full textIn the summer of 2010, the Geological Survey of Denmark and Greenland (GEUS) mapped the potential raw materials and substrate types, over large parts of the Danish economic sector of the North Sea, in cooperation with Orbicon A/S. The mapping was carried out for the Danish Nature Agency; it is part of the general mapping of raw material resources within the territories of the Danish state and forms part of the input for the implementation of the European Union’s Marine Strategy Framework Directive. The purpose was (1) to provide an overview of the distribution, volume and composition of available raw materials and (2) to identify, describe and map the distribution of the dominant marine bottom types
Review of Survey activities 2010
No full textThis Review of Survey activities presents a selection of 19 papers reflecting the wide spectrum of activities of the Geological Survey of Denmark and Greenland, from the microscopic to the plate-tectonic level. The Survey\u27s activities in Denmark and surrounding areas are illustrated by 12 articles covering petroleum geology, groundwater geology, applied marine geology, Quaternary stratigraphy, sea-level changes, disposal of radioactive waste and the use of satellite radar data to detect elevation changes. The depth of two earthquakes has been determined using data from array stations in Canada and Niger. Activities in Greenland are covered by six papers dealing with mineral and petroleum exploration. One paper comes with further evidence that the controversial Wegener Fault is a myth. The influence of recent climate change on the Greenland ice sheet is the subject of another article; 2010 was the warmest year ever recorded in Greenland, and the ice sheet is losing mass at an accelerating rate. The Survey\u27s international activities are the subject of a paper dealing with quality control of geophysical data in Ghana
Does road salt affect groundwater in Denmark?
No full textChloride (Cl) from dissolved salt is a major threat to groundwater quality in many regions of the world. In arid regions near present-day coastlines, where old seawater occurs in deeper sediments and where road salt is frequently used, Cl can be a significant pollutant (European Environmental Agency 2009). European Union member states have recently reported that next to nitrogen, Cl is the most commonly found pollutant and is often responsible for groundwater bodies being at risk or having a poor ecological status (European Commission 2010)
Mapping porosity anomalies in deep Jurassic sandstones – an example from the Svane-1A area, Danish Central Graben
No full textHydrocarbon-bearing Upper Jurassic sandstone reservoirs at depths of more than 5000 m may form a future exploration target in the Danish Central Graben (Fig. 1). The Upper Jurassic sandstone play in the Danish sector has historically been less successful than in the neighbouring Norwegian and British sectors of the North Sea. This is mainly due to poor reservoir quality of the sandstones. However, the discovery in 2001 of an oil accumulation at a depth of more than 5000 m in the Svane-1 well has triggered renewed interest in the Upper Jurassic High Temperature – High Pressure (HTHP) sandstone play in Danish waters. The Jurassic plays comprise sandstone reservoirs deposited in a variety of environments, ranging from fluvial to deep marine
A new Middle Pleistocene interglacial sequence from Måløv, Sjælland, Denmark
No full textInterglacial deposits in Denmark have traditionally been referred to the Cromerian complex (Hareskovian), Holsteinian or Eemian stages. However, based on studies of sediment cores from the deep sea many more than three Quaternary interglacials have been documented, and in other parts of north-western Europe it is becoming increasingly clear that the on-shore Quaternary sequences are much more complex than previously believed. Interglacial deposits are characterised by plant and animal remains indicating longer periods with climatic conditions similar to or warmer than today, whereas interstadial deposits were formed during shorter time spans and usually contain remains of relatively cold-adapted, arctic or sub-arctic species. Interglacial and interstadial deposits can be dated more or less precisely, and thus provide information about the relative age of glacial deposits