GEUS Bulletin https://geusbulletin.org/index.php/geusb <p>GEUS Bulletin is a peer-reviewed, open access journal published by the&nbsp;<a href="https://eng.geus.dk/" target="_blank" rel="noopener">Geological Survey of Denmark and Greenland (GEUS)</a>. We publish geoscience research papers, monographs and map descriptions for Denmark, Greenland and the Arctic region. GEUS Bulletin believes that open science benefits scientists, industry and society. We do not charge publication fees and all our articles can be freely downloaded online.</p> Geological Survey of Denmark and Greenland (GEUS) en-US GEUS Bulletin 1604-8156 <p><span data-contrast="auto">GEUS Bulletin is an open-access, peer-reviewed journal published by the Geological Survey of Denmark and Greenland (GEUS). This article is distributed under a&nbsp;</span><a href="https://creativecommons.org/licenses/by/4.0/"><span data-contrast="none">CC-BY 4.0 licence</span></a><span data-contrast="auto">, permitting free redistribution and reproduction for any purpose, even commercial, provided proper citation of the original work. Author(s) retain copyright over the article contents. Read the </span><a href="https://geusbulletin.org/index.php/geusb/oapolicy">full open access policy</a>.</p> Preliminary landslide mapping in Denmark indicates an underestimated geohazard https://geusbulletin.org/index.php/geusb/article/view/5302 <p>The process of coastal erosion is well known to the public and decision-makers in Denmark; however, there is little awareness of the risks posed by larger landslides. Only a few scientific studies investigate landslides in Denmark, and as a result, the country is underrepresented in international landslide inventories. Here, we present a systematically produced preliminary landslide inventory based on digital elevation models and high-resolution orthophotos. So far, the preliminary inventory documents 3026 morphological expressions of landslides close to the coast and inland, showing that landslides are more widespread in Denmark than previously recognised. A number of these landslides are near buildings and infrastructure. This paper therefore highlights the potential for geohazardous landslides to occur in Denmark on a national scale and discusses some of the implications. Two of the major questions arising from this study are (1) how to approach potential geohazards in a country with no framework or precedence for landslide hazard and risk management and (2) how landslides and associated risk in Denmark will evolve under a changing climate.</p> Kristian Svennevig Gregor Lützenburg Marie K. Keiding Stig Asbjørn Schack Pedersen Copyright (c) 2020-11-09 2020-11-09 10.34194/geusb.v44.5302 The lower Miocene flint conglomerate, Jylland, Denmark: a result of the Savian tectonic phase https://geusbulletin.org/index.php/geusb/article/view/4618 <p>The early Miocene was an important period for the development of the eastern North Sea. Tectonism in North-West Europe resulted in uplift of the Scandinavian mountains, reactivation of salt structures, inversion of old graben structures and deposition of the most coarse-grained deposits in the Danish pre-Quaternary succession. Some of these deposits were later cemented into conglomerates. The deposits are common in the fluvial parts of the Billund Formation (Aquitanian) and the basal transgressive lag of the late Aquitanian – Burdigalian Klintinghoved Formation capping the Billund Formation. Questions remained as to the age of these deposits and what they infer about tectonic events in the region. This study reviews the geology of the flint-dominated conglomerates and presents the first dates for a sample of these unique deposits. We observe grain sizes up to 5 cm diameter. Palynological analyses place the sample as early Miocene. Some samples from the area have suggested a local source near active salt structures, associated with the uplift of the pre-Neogene sedimentary successions. We suggest that the common occurrences of flint clasts in the lower Miocene succession reveal significant erosion of Upper Cretaceous and Danian chalk, likely associated with the uplift of the Scandinavian lowlands during the Savian tectonic phase, early Miocene.</p> Erik Skovbjerg Rasmussen Karen Dybkjær Copyright (c) 2020 Erik Skovbjerg Rasmussen, Karen Dybkjær https://creativecommons.org/licenses/by/4.0 2020-11-02 2020-11-02 10.34194/geusb.v44.4618 Petrography, geochemistry and magnetic susceptibility of the Isortoq Fe-Ti-V deposit, Isortoq Giant Dykes, South Greenland https://geusbulletin.org/index.php/geusb/article/view/4626 <p>The Isortoq Giant Dykes in the Proterozoic Gardar Province, South Greenland, include the Isortoq South giant dyke and the Isortoq North giant dyke. The fine-grained Fe-Ti-V deposit hosted by the Isortoq South giant dyke, referred to as the Isortoq Fe-Ti-V deposit, is considered a good test site for the use of magnetic susceptibility for the mapping of ore grades. Here, we test this and show that the Fe, Ti and V distribution is controlled by titanomagnetite disseminated throughout fine-grained troctolite. The deposit displays a clear correlation between magnetic susceptibility and Fe, Ti and V grades in bulk samples of consecutive 2 m sections from 11 drill cores, totalling 2671 m in length. We observe that Fe, Ti and V are almost entirely hosted in titanomagnetite, which controls the magnetic susceptibility. Field measurements of the magnetic susceptibility can thus be considered as a reliable exploration tool for this type of mineralisation. We further consider the origins of the deposit by reconnaissance petrography, mineral and bulk rock chemistry of the large mass of aphanitic Fe-rich troctolite in the Isortoq South giant dyke. We suggest that the deposit may represent the base of a basanitic to trachybasaltic magma chamber, in which Fe-rich immiscible melts accumulated, crystallised and fractionated. The processes suggested here may apply to other giant dykes and intrusions of the Gardar Province.</p> Diogo Rosa Alessandro Sandrin Troels F.D. Nielsen Høgni Vesturklett Copyright (c) 2020 Diogo Rosa, Alessandro Sandrin, Troels Nielsen, Høgni Vesturklett https://creativecommons.org/licenses/by/4.0 2020-08-21 2020-08-21 10.34194/geusb.v44.4626 Geophysics for urban mining and the first surveys in Denmark: rationale, field activity and preliminary results https://geusbulletin.org/index.php/geusb/article/view/5240 <p>Geophysical methods have been widely used in recent decades to investigate and monitor landfill sites for environmental purposes. With the advent of the circular economy, waste contained in old landfills may be considered a resource that can be developed. Since the content of old landfills is largely unknown, the occurrence and quantity of valuable materials must be investigated before embarking on any development activity. Two landfills on Sjælland, Denmark (located at Hvalsø and Avedøre) were selected for a pilot study to characterise their content. At both locations, a set of geophysical surveys is underway. Here, we present the data obtained from magnetic and 2D seismic refraction surveys. Magnetic data show various anomalies that can be interpreted as caused by iron-rich waste. At both sites, the landfill material results in generally low P-wave velocity (&lt;400 m/s), lower than those obtained for Quaternary sediments at Avedøre. The seismic velocities appear to increase in the presence of metals or by compaction with depth (&gt;550 m/s). We propose that seismic refraction can thus define the bottom of the landfill and possibly its internal structure, especially when combined with other methods.</p> Alessandro Sandrin Aleksandar Maricak Björn H. Heincke Rune J. Clausen Lars Nielsen Jakob K. Keiding Copyright (c) 2020 Alessandro Sandrin, Aleksandar Maricak, Björn H. Heincke, Rune J. Clausen, Lars Nielsen, Jakob K. Keiding https://creativecommons.org/licenses/by/4.0 2020-07-02 2020-07-02 10.34194/geusb.v44.5240 Late Quaternary history of Lammefjorden, north-west Sjælland, Denmark https://geusbulletin.org/index.php/geusb/article/view/4630 <p>Lammefjorden is a reclaimed fjord in north-west Sjælland, Denmark. Sediment cores from the area were collected to study its development after the last deglaciation, in particular the sea-level history. Late glacial and Early Holocene lake and bog deposits occur below marine deposits. Sparse late glacial fossil assemblages indicate tree-less environments with dwarf-shrub heaths. Early Holocene deposits contain remains of <em>Betula</em> sec. <em>Albae</em> sp. and <em>Pinus sylvestris</em>, which indicate open forests. The wetland flora comprised the calciphilous reed plant <em>Cladium mariscus</em> and the water plant <em>Najas marina</em>. Marine gyttja from basins is characterised by sparse benthic faunas, probably due to high sedimentation rates. In some areas, shell-rich deposits were found, with large shells of<em> Ostrea edulis</em>, indicative of high summer temperatures, high salinity and strong tidal currents. A marine shell dated to 6.7 cal. ka provides a minimum age for the marine transgression of Lammefjorden.</p> Ole Bennike Peter Roll Jakobsen Jakob Walløe Hansen Copyright (c) 2020 Ole Bennike, Peter Roll Jakobsen, Jakob Walløe Hansen https://creativecommons.org/licenses/by/4.0 2020-06-25 2020-06-25 10.34194/geusb.v44.4630 Semi-conventional play: definition, exploration strategy and the example of the Chalk Group in Denmark https://geusbulletin.org/index.php/geusb/article/view/4836 <p>Play analysis has been widely used in hydrocarbon exploration for decades with great success. In recent years, progress has also been made to describe reservoir properties of very low permeability reservoirs. However, comparatively little research has been done into play analysis for such reservoirs, which may lead to misleading estimates of their hydrocarbon potential. Here, the concept of a semi-conventional play is defined and characterised as having a reservoir of such low permeability that a hydrocarbon column can form down-dip of an effective dry trap. A new exploration approach is proposed for such plays, using the Chalk Group Play in the Danish North Sea as an example. It is suggested that together with the usual risk elements, a more detailed analysis of ‘charge’ is necessary, paying particular attention to identifying possible hydrocarbon entry points, palaeostructures and the maximum distance from these entry points that the hydrocarbons may have reached since they first entered the reservoir. The application of this novel approach for semi-conventional plays in mature basins can help unlock further resources in proximity of existing fields, and reduce the risk of failure in frontier exploration.</p> Alessandro Sandrin Copyright (c) 2020 Alessandro Sandrin https://creativecommons.org/licenses/by/4.0 2020-05-26 2020-05-26 10.34194/geusb.v44.4836 Characterisation of incinerator bottom ash from a Danish waste-to-energy plant: a step towards closing the material cycle https://geusbulletin.org/index.php/geusb/article/view/4305 <p>The UN Sustainable Development Goal 12, regarding responsible production and consumption of raw materials, guides ongoing international efforts to enhance sustainability in all parts of the mineral sector. Of particular interest, is improving the recyclability of secondary waste streams and thereby increasing the efficiency of recycling end-of-life products. Municipal solid waste – residual waste from household and industry – constitutes one of these secondary streams. It is typically incinerated in waste-to-energy plants producing two types of waste streams that carry a raw material resource potential: incinerator bottom ash (IBA) and incinerator fly ash (IFA). IBA is of particular interest in the recycling industry, where it is commonly recycled to produce three main fractions: (i) ferrous material, (ii) non-ferrous material, and (iii) residual slag. In most cases the two metal fractions are separated further downstream in the value chain, prior to smelting. The residual, non-magnetic fraction (typically 0–45 mm) is used mainly as construction aggregate. Improvements in the efficiency of existing separation technologies are still being made, but less effort is focussed on characterising the fundamental composition and mineral resource potential of IBA. For this reason, the Urban-X project was launched by the Geological Survey of Denmark and Greenland (GEUS) to characterise the composition and resource potential of various waste streams at Amager Bakke waste-to-energy plant in Copenhagen, Denmark. This paper discusses some of the main outcomes of the Urban-X project with respect to IBA, and a full analysis of all waste streams analysed at Amager Bakke is available in Clausen&nbsp;<em>et al</em>. 2019.</p> Rune J. Clausen Per Kalvig Jonas Nedenskov Copyright (c) 2019-12-20 2019-12-20 10.34194/GEUSB-201943-03-03 Review of Survey activities 2018 https://geusbulletin.org/index.php/geusb/article/view/4218 <p>Every four years the Geological Survey of Denmark and Greenland (GEUS) develops and implements new strategies to ensure that we are able to help meet the ever-changing challenges that face society. In 2018 these discussions were shaped by important issues like climate change and climate adaptation, and their consequences for our use of energy, minerals and water resources. As part of this strategic focus, GEUS introduced a new publication strategy in 2018 that seeks to increase our publication rate of high impact science, and to gain more visibility within the international scientific community and the media. Many different tools will be applied to make such a long-term cultural change possible, including modernisation of GEUS’ own publication series.</p> Flemming G. Christiansen Copyright (c) 2019-08-07 2019-08-07 10.34194/GEUSB-201943-00-01 Developing multi-sensor drones for geological mapping and mineral exploration: setup and first results from the MULSEDRO project https://geusbulletin.org/index.php/geusb/article/view/4211 <p>The use of Unmanned Aerial Systems (UAS), also known as drones, is becoming increasingly important for geological applications. Thanks to lower operational costs and ease of use, UAS offer an alternative approach to aircraft-based and ground-based geoscientific measurements (Colomina &amp; Molina 2014). Magnetic and hyperspectral UAS surveys hold particular promise for mineral exploration, and several groups have recently published studies of magnetic data collected by UAS for such applications (Malehmir&nbsp;<em>et al</em>. 2017; Cunningham&nbsp;<em>et al</em>. 2018), although equivalent studies using hyperspectral data are still rare (Kirsch&nbsp;<em>et al</em>. 2018). Combining both techniques is particularly useful. Magnetic measurements play an important role in mineral exploration, since magnetisation in rocks is mainly associated with magnetite and other iron minerals, which can be used in mapping and targeting of mineral deposits (Dentith &amp; Mudge 2014). Hyperspectral imaging (HSI) is a powerful exploration and mapping technique in areas where the rock surface is well-exposed, and where geological units and mineral compositions can be estimated from spectral features of the electromagnetic spectrum in the visual and infrared range.</p> Björn Heincke Robert Jackisch Ari Saartenoja Heikki Salmirinne Sönke Rapp Robert Zimmermann Markku Pirttijärvi Erik Vest Sörensen Richard Gloaguen Lisa Ek Johan Bergström Arto Karinen Sara Salehi Yuleika Madriz Maarit Middleton Copyright (c) 2019-07-29 2019-07-29 10.34194/GEUSB-201943-03-02 The North Atlantic Provenance Database: an introduction https://geusbulletin.org/index.php/geusb/article/view/4221 <p class="p1">The amount of provenance information available for onshore and offshore sedimentary deposits in the North Atlantic Region is substantial and rapidly increasing. These data provide an improved understanding of reservoir geology (quality, diagenetic issues, regional source-to-sink relations and local stratigraphic correlations), and thereby can reduce hydrocarbon exploration risk.<span class="Apple-converted-space">&nbsp;</span>As such, the number of proprietary, industry-related and public research provenance studies has increased considerably in recent years, and the development and use of new analytical techniques has also caused a surge in the number of grains, isotopes and chemical elements analysed in each study. As a result, it is today close to impossible for the individual researcher or petroleum geologist to draw on all existing provenance data. And the vast expansion of data availability demands new and better methods to analyse and visualise large amounts of data in a systematic way</p> <p class="p1">To this end, the Geological Survey of Denmark and Greenland (GEUS) and the Norwegian Petroleum Directorate (NPD) have established a web-based database of provenance data for the North Atlantic area: the North Atlantic Provenance Database. Construction of the database was funded jointly by GEUS and NPD. Future maintenance and further development will be funded by the petroleum industry by subscription to the database.<span class="Apple-converted-space">&nbsp;</span>Here, we provide a brief introduction to the database and its future development and expansion. We highlight the current capabilities with an example from East Greenland.<span class="Apple-converted-space">&nbsp;</span></p> Christian Knudsen Martin Sønderholm Tjerk Heijboer Jeppe Å. Kristensen Dag Bering Copyright (c) 2019-07-22 2019-07-22 10.34194/GEUSB-201943-03-01 Distribution of porosity-preserving microquartz coatings in sandstones, Upper Jurassic Danish Central Graben https://geusbulletin.org/index.php/geusb/article/view/4223 <p>High porosity is a key factor for good reservoir sandstones for both hydrocarbon and geothermal energy exploitation. The porosity of sandstones generally decreases with increased burial depth due to compaction and cementation. However, some sandstones in the North Sea show higher porosity than expected for their burial depth, due to the presence of micro­quartz coatings (e.g. Aase&nbsp;<em>et al</em>. 1996; Hendry &amp; Trewin 1995; Jahren &amp; Ramm 2000; Maast&nbsp;<em>et al</em>. 2011). Siliceous sponge spicules have been documented to be an internal source of silica that promotes microquartz coatings (e.g. Hendry &amp; Trewin 1995; Aase&nbsp;<em>et al</em>. 1996). Siliceous sponge spicules, the solid ‘skeleton’ of sponges, consist of opal-A and will dissolve when exposed to higher temperatures, thereby causing supersaturation of the formation water with respect to opal-CT and quartz, resulting in nucleation of numerous small (1–5 µm) quartz crystals (Williams&nbsp;<em>et al</em>. 1985; Hendry &amp; Trewin 1995). To predict reservoir quality it is important to understand the distribution of porosity-preserving microquartz in clastic deposits, and yet this is still poorly understood. To address this, our study presents petrographical analyses of cored sandstone sections from wells of various depositional environments, including<span class="Apple-converted-space">&nbsp;&nbsp;</span>back-barrier, estuarine, shoreface and gravity flows, as well as various present-day burial depths across the Danish Central Graben.&nbsp;</p> <p>&nbsp;</p> Margrethe T. Nielsen Rikke Weibel Jens Therkelsen Henrik Friis Copyright (c) 2019-07-22 2019-07-22 10.34194/GEUSB-201943-01-03 Liverpool Land Basement High, Greenland: visualising inputs for fractured crystalline basement reservoir models https://geusbulletin.org/index.php/geusb/article/view/4298 <p class="p1">Basement highs are large structural features, commonly buried in sedimentary basins (Busby &amp; Azor 2012). They are of interest for natural resources exploration and research because of their ability to influence migration and entrapment of petroleum (Trice 2014) and water, and the deposition of metals (Hitzman 2005; Borg&nbsp;<em>et al</em>. 2012). Three-dimensional (3D) reservoir models (e.g. Shepherd 2009) are built to evaluate and model fluid-filled basement reservoirs (Ringrose &amp; Bentley 2015). However, subsurface data are expensive, difficult to obtain and are often widely spaced. Ideally, basement reservoir models would be constrained by rock, fracture and mineral vein data from appropriate outcrop analogues (acknowledging that subaerial basement rocks have, by definition, a different uplift history than subsurface basement). The Liverpool Land Basement High (LLBH) in Greenland is an uplifted and well-exposed basement high located between two sedimentary basins, and thus provides a valuable analogue for fractured basement-hosted mineral, oil and geothermal reservoirs.<span class="Apple-converted-space">&nbsp;</span></p> <p class="p1">The Geological Survey of Denmark and Greenland (GEUS) conducted reconnaissance work on the LLBH in 2018 to assess the quality of the exposure of basement palaeo-weathering profiles and fault-fracture networks. Here, we introduce the LLBH, the concept of fractured basement reservoir modelling, and how studying the LLBH can help enhance reservoir modelling of fractured basement. We present some of our preliminary observations of LLBH fault-fracture networks and discuss how the exposed sediment-basement features and processes might aid industry&nbsp;<span class="s1">and research in their top basement mapping activities. We propose that LLBH provides a particularly suitable analogue for industry and research to analyse: (a) multiscale fracture system connectivity, (b) fluid migration and fluid-rock reaction processes, (c) input parameters for basement reservoir modelling and (d) top basement geomorphologies and processes.</span></p> Graham Banks Stefan Bernstein Sara Salehi Pierpaolo Guarnieri Dennis Bird Catherine Hamblett David Peacock Jon Foster Copyright (c) 2019-07-22 2019-07-22 10.34194/GEUSB-201943-02-04 Characterising brines in deep Mesozoic sandstone reservoirs, Denmark https://geusbulletin.org/index.php/geusb/article/view/4224 <p>The Danish subsurface contains several sandstone units, which represent a large geothermal resource (Vosgerau&nbsp;<em>et al</em>. 2016). Currently, only three geothermal plants are operating in Denmark, but several exploration licences are expected to be awarded in 2019. Geothermal energy is exploited from deeply buried porous sandstones by bringing warm form­ation water (brine) to the surface, extracting the heat and returning the cooled water to the same sandstones. The reduced temperature of the brine during this process implies a risk of scaling, which may reduce reservoir permeability and hence injectivity. Predicting the chemical composition of formation waters, however, could help to reduce the risk associated with scaling in planned geothermal facilities.</p> <p class="p1">Here, we present a regional overview of the geochem­istry of brines from deep Mesozoic sandstones in the Danish Basin and North German Basin that supplements previous studies, notably by Laier (2002, 2008). The brine composition at shallow burial typically reflects the original (connate) formation water chemistry, which is determined by the original depositional environment of the sandstone, for example fluvial or marine. However, the mineralogical composition of the sandstone changes during burial, whereby some minerals may dissolve or precipitate when exposed to higher temperatures. These mineral changes are reflected in the brine composition, which typically becomes more saline with increased burial (e.g. Laier 2008; Kharaka &amp; Hanor 2003).<span class="Apple-converted-space">&nbsp;</span></p> <p class="p1">The brine chemistry reported here shows a distinct depth trend, which reflects original connate formation waters that are modified through burial diagenesis. We have classified the brines into brine types, which are shown to be related to their depositional environment, depth, geological formation and geographical domains.</p> <p class="p1">&nbsp;</p> Hanne D. Holmslykke Niels H. Schovsbo Lars Kristensen Rikke Weibel Lars Henrik Nielsen Copyright (c) 2019-07-17 2019-07-17 10.34194/GEUSB-201943-01-04 Comparison of ASTER and Sentinel-2 spaceborne datasets for geological mapping: a case study from North-East Greenland https://geusbulletin.org/index.php/geusb/article/view/4299 <p>Spaceborne remote sensing is a suitable tool for early mineral exploration and surveying large areas of high Arctic environment in a fast and cost-effective manner. While spaceborne data have been used widely to map geology in arid areas, similar approaches for remotely-sensed geological mapping of Arctic environments is yet to be developed. Freely available spaceborne optical data provides detailed information of high-quality that could potentially reduce resource exploration risk in remote regions. To this end, this study compares the use of two different multispectral spaceborne datasets (i.e. the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Sentinel-2) to map geological units in and around Wollaston Forland, North-East Greenland – an area rich in Jurassic and Cretaceous sedimentary rocks and important targets for offshore petroleum exploration. Multispectral image sensors simultaneously capture image data within multiple wavelength ranges (bands) across the electromagnetic spectrum. Each band is commonly described by the band number and the band wavelength centre position. Here, we identify the bands most suitable for geological mapping in an Arctic setting, using the Wollaston Forland area as an example. We compare the results obtained by processing spaceborne data with a published geological map for the area (Henriksen 2003).</p> Sara Salehi Christian Mielke Christian Brogaard Pedersen Simun Dalsenni Olsen Copyright (c) 2019-07-17 2019-07-17 10.34194/GEUSB-201943-02-05 Mapping glacial rock flour deposits in Tasersuaq, southern West Greenland https://geusbulletin.org/index.php/geusb/article/view/4300 <p>Global population has increased rapidly in recent decades. So far, it has been possible to feed the growing population by using more and more land for agriculture, using irrigation and artificial fertilisers and by improving the efficiency of agriculture. Recently the growth of the global agricultural area has slowed. However, the need for food will continue to grow markedly in coming years. This demand can no longer be met by using increasingly more land for agriculture, and in many areas it is not possible to increase crop production by irrigation (Wise 2013).</p> <p>Large areas in the tropics are characterised by strongly depleted soils with low concentrations of nutrients such as nitrogen, phosphorous and potassium. In such areas, the yield of crop per hectare is much lower than the theoretical yield using optimal fertilising (Ray&nbsp;<em>et al.</em>&nbsp;2013). Reducing the gap between real and potential crop productivity offers the best solution to achieve food security for the world’s rapidly growing population.</p> <p>Poor soil quality in the tropics is largely due to the rapid weathering of minerals and leaching of dissolved nutrients in the warm and humid climate. If weathered minerals are not replaced by new minerals, for example due to volcanic activity, then soil fertility continues to decline over time. Therefore, it is necessary to use increasing amounts of fertilisers to feed growing populations in the tropics. Most nutrients come from geological deposits; the only exception is nitrogen, which can be extracted from the atmosphere. Nutrients that are mined constitute a limited resource. Hence the known occurrences of phosphorous can only cover the current demand for a few decades (van Vuuren&nbsp;<em>et al.</em>&nbsp;2010).</p> <p>In recent years, investigations have been conducted to see if the productivity of nutrient-poor soils can be improved by the application of glacial rock flour from Greenland. Rock flour in southern West Greenland consists of fine-grained silt, formed by the grinding of bedrock by stones and boulders embedded in the basal part of glaciers. Preliminary results indicate that plants cultivated in soils with rock flour can achieve increased growth (M.T. Rosing, unpublished data 2019). However, the research is still in its early days and many questions remain. We do not know why adding rock flour to soil results in increased growth. Maybe the silt fraction improves the soil properties. Also we do not know if it is feasible to mine rock flour and transport it to the tropics. As a first step towards answering some of these questions, our aim here was to simply map and sample the glacial rock flour in Tasersuaq, a large proglacial lake in southern West Greenland,&nbsp;<em>c.</em>&nbsp;105 km north-east of Nuuk.</p> Ole Bennike Jørn Bo Jensen Frederik Næsby Sukstorf Minik T. Rosing Copyright (c) 2019-07-17 2019-07-17 10.34194/GEUSB-201943-02-06 Greenland ice sheet mass balance assessed by PROMICE (1995–2015) https://geusbulletin.org/index.php/geusb/article/view/4276 <p>The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) has measured ice-sheet elevation and thickness via repeat airborne surveys circumscribing the ice sheet at an average elevation of 1708 ± 5 m (Sørensen<em>&nbsp;et al.</em>&nbsp;2018). We refer to this 5415 km survey as the ‘PROMICE perimeter’. Here, we assess ice-sheet mass balance following the input-output approach of Andersen<em>&nbsp;et al</em>. (2015). We estimate ice-sheet output, or the ice discharge across the ice-sheet grounding line, by applying downstream corrections to the ice flux across the PROMICE perimeter. We subtract this ice discharge from ice-sheet input, or the area-integrated, ice sheet surface mass balance, estimated by a regional climate model. While Andersen<em>&nbsp;et al</em>. (2015) assessed ice-sheet mass balance in 2007 and 2011, this updated input-output assessment now estimates the annual sea-level rise contribution from eighteen sub-sectors of the Greenland ice sheet over the 1995–2015 period.</p> William Colgan Kenneth D. Mankoff Kristian K. Kjeldsen Anders A. Bjørk Jason E. Box Sebastian B. Simonsen Louise S. Sørensen S. Abbas Khan Anne M. Solgaard Rene Forsberg Henriette Skourup Lars Stenseng Steen S. Kristensen Sine M. Hvidegaard Michele Citterio Nanna Karlsson Xavier Fettweis Andreas P. Ahlstrøm Signe B. Andersen Dirk van As Robert S. Fausto Copyright (c) 2019-07-08 2019-07-08 10.34194/GEUSB-201943-02-01 U-Pb dating identifies titanite precipitation in Paleogene sandstones from a volcanic terrane, East Greenland https://geusbulletin.org/index.php/geusb/article/view/4297 <p>Titanite (CaTiSiO<sub>5</sub>) occurs as a rare mineral in magmatic and metamorphic rocks. It is commonly found in clastic sedimentary rocks as an accessory heavy mineral – a mineral of high density.&nbsp;Recently, U-Pb dating of single-grains of detrital titanite has been shown to be a useful tool in sedimentary provenance studies (e.g. McAteer&nbsp;<em>et al</em>. 2010; Thomsen&nbsp;<em>et al</em>. 2015). Titanite U-Pb geochronologies can add important information to constrain the sediment sources of rocks and basins, and can help date precipitation of titanite. However, there are a number of complicating factors that must be taken into consideration for reliable application of titanite U-Pb dating in provenance studies.</p> <p>First, titanite is less stable than zircon – the most commonly employed dating target. For example, in Palaeocene sediments in the North Sea, titanite rarely occurs as detrital grains at burial depths greater than 1400 m (Morton 1984). It can also show dissolution features due to weathering and burial diagenesis (e.g. Morton 1984; Turner &amp; Morton 2007). Second, titanite may precipitate during burial diagenesis, which would reflect the burial history of sediments and not their provenance. Precipitation of authigenic titanite is documented from deeply buried (i.e. at temperatures greater than 100°C) volcaniclastic sandstones and mudstones (Helmond &amp; Van de Kamp 1984; Milliken 1992) and intrusion-associated mineralisation in volcanic Permian sandstones (van Panhuys-Sigler &amp; Trewin 1990). Moreover, titanite also occurs in shallow-buried Jurassic sandstones with no volcanic affinity (Morad 1988). Thus, the formation of titanite is not necessarily linked to a volcaniclastic source, but nevertheless, the presence of volcanic material seems to promote titanite precipitation. If authigenic titanite precipitation was incorrectly identified as detrital, this would have considerable implications for provenance investigations, as apparently titanite-rich source rocks would be wrongly inferred to be present in the sediment source area. Here, we present examples from the Kangerlussuaq Basin in southern East Greenland of what appeared to be detrital titanite. However, new U-Pb dating reveals that the titanite formed authigenically, and hence contributed to the burial history, and not the provenance, of the sediments.</p> Rikke Weibel Tonny B. Thomsen Copyright (c) 2019-07-08 2019-07-08 10.34194/GEUSB-201943-02-03 Sea-level rise in Denmark: Bridging local reconstructions and global projections https://geusbulletin.org/index.php/geusb/article/view/4220 <p>Between 1850 and 2006 global mean sea level rose by 24 ± 18 cm. It is projected to rise a further 52 ± 21 cm under the Representative Concentration Pathway (RCP) 4.5 scenario, which approximates the carbon emissions reductions of the ‘Paris Agreement’ climate pathway. It is projected to rise 74 ± 28 cm under the RCP8.5 scenario, which represents a ‘business-as-usual’ climate pathway (Box &amp; Colgan 2017). These rates of recent and future sea-level rise are faster than those reconstructed for previous warm intervals, such as the Medieval Climatic Optimum (<em>c</em>. 1000 to 1400 CE) and the Holocene Thermal Maximum (<em>c.</em>&nbsp;7000 to 3000 BCE) (Gehrels &amp; Shennan 2015). Moreover, palaeo reconstructions indicate a global sea-level sensitivity of two metres per degree of warming (Levermann&nbsp;<em>et al</em>. 2013).</p> <p>The forces driving global sea-level change are complex. The global sea-level budget includes the transfer of land ice into the ocean, thermal expansion of seawater, changes in land water storage, and changes in ocean basin volume (Church&nbsp;<em>et al</em>. 2013). At the local scale, the evolving planetary gravity due to shifting water and ice masses, shifting oceanic and atmospheric currents and persistent tectonic and glacial isostatic adjustment processes can also be important. Sea-level changes around the globe are therefore far from uniform (Jevrejeva&nbsp;<em>et al</em>. 2016).</p> <p>Here, we highlight the value of combining palaeo reconstructions of sea level, the measured tide gauge record, and projections of future sea level. This allows us to understand local sea-level changes from the recent past in the context of global projections for the near future (0 to 2100 CE). We explore the strong differences in local sea-level histories and future projections at three Danish cities: Skagen and Esbjerg, as they have contrasting glacio-isostatic adjustment histories, and Copenhagen, where we also compare local and global drivers of present-day sea-level rise based on previously published research.</p> William Colgan Jason E. Box Sofia Ribeiro Kristian K. Kjeldsen Copyright (c) 2019-07-01 2019-07-01 10.34194/GEUSB-201943-01-01 A multidisciplinary approach to landslide monitoring in the Arctic: Case study of the March 2018 ML 1.9 seismic event near the Karrat 2017 landslide https://geusbulletin.org/index.php/geusb/article/view/4302 <p>The landslide of 17 June 2017 at Karrat Fjord, central West Greenland, triggered a tsunami that caused four fatalities. The catastrophe highlighted the need for a better understanding of landslides in Greenland and initiated a recent nation-wide landslide screening project led by the Geological Survey of Denmark and Greenland (GEUS; see also&nbsp;<a href="https://doi.org/10.34194/GEUSB-201943-02-07">Svennevig (2019)&nbsp;this volume</a>).</p> <p>This paper describes an approach for compiling freely available data to improve GEUS’ capability to monitor active landslides in remote areas of the Arctic in near real time. Data include seismological records, space borne Synthetic Aperture Radar (SAR) data and multispectral optical satellite imagery. The workflow was developed in 2018 as part of a collaboration between GEUS and scientists from the Technical University of Denmark (DTU). This methodology provides a model through which GEUS will be able to monitor active landslides and provide relevant knowledge to the public and authorities in the event of future landslides that pose a risk to human life and infrastructure in Greenland.</p> <p>We use a minor event on 26 March 2018, near the site of the Karrat 2017 landslide, as a case study to demonstrate 1) the value of multidisciplinary approaches and 2) that the area around the landslide has continued to be periodically active since the main landslide in 2017.</p> Kristian Svennevig Anne Munck Solgaard Sara Salehi Trine Dahl-Jensen John Peter Merryman Boncori Tine B. Larsen Peter H. Voss Copyright (c) 2019-07-01 2019-07-01 10.34194/GEUSB-201943-02-08 Update of annual calving front lines for 47 marine terminating outlet glaciers in Greenland (1999–2018) https://geusbulletin.org/index.php/geusb/article/view/4296 <p>The Greenland ice sheet has been losing mass in response to increased surface melting (Khan&nbsp;<em>et al</em>. 2015; van den Broeke&nbsp;<em>et al</em>. 2017) as well as discharge of ice from marine terminating outlet glaciers (van den Broeke&nbsp;<em>et al</em>. 2009; Box&nbsp;<em>et al</em>. 2018). Marine terminating outlet glaciers flow to the ocean where they lose mass by e.g. iceberg calving. Currently, the mass loss from the Greenland ice sheet is the largest Arctic contributor to global sea-level rise (van den Broeke&nbsp;<em>et al</em>. 2009, 2017; Box&nbsp;<em>et al</em>. 2018). Therefore, monitoring&nbsp;changes in the Greenland ice sheet is essential to provide policy makers with reliable data.</p> <p>There is a consensus that most&nbsp;marine terminating outlet glaciers have retreated in recent decades, and that the increased calving rates are a response to recent atmospheric and oceanic warming (e.g. Box&nbsp;<em>et al</em>. 2018; Moon&nbsp;<em>et al</em>. 2018). The rate of dynamic mass loss is determined by changes of the glacier calving front (i.e. its terminus) position, ice thickness and changes in ice flow.&nbsp;Ocean temperature and fjord circulation also influence the calving front stability by melting the glacier below the water line, thinning the ice that is in contact with water (Moon&nbsp;<em>et al</em>. 2014). Change in calving front position is therefore an important indicator for monitoring the dynamic behaviour of the upstream area of the ice sheet, which is further modulated by local topographic features and buttressing effects (Rignot &amp; Kanagaratnam 2006; Nick&nbsp;<em>et al</em>. 2009).</p> <p>The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) is dedicated to monitoring changes in the mass budget of the Greenland ice sheet, including monitoring of the calving front lines of&nbsp;marine terminating outlet glaciers. Here, we present an updated collection of annual measurements of end-of-melt-season calving front lines for 47 marine terminating outlet glaciers in Greenland between 1999 and 2018. We also present an example application of the data set, in which we estimate area changes for this group of glaciers since 1999. The Greenland calving front lines were measured from optical satellite imagery obtained from Landsat, Aster, and Sentinel-2 (Table 1). The&nbsp;<a href="http://www.promice.org/home.html" target="_blank" rel="noopener" data-externalcookie="false">PROMICE calving front product&nbsp;</a>is freely available for download as ESRI shapefiles.</p> Jonas K. Andersen Robert S. Fausto Karina Hansen Jason E. Box Signe B. Andersen Andreas P. Ahlstrøm Dirk van As Michele Citterio William Colgan Nanna B. Karlsson Kristian K. Kjeldsen Niels J. Korsgaard Signe H. Larsen Kenneth D. Mankoff Allan Ø. Pedersen Christopher L. Shields Anne Solgaard Baptiste Vandecrux Copyright (c) 2019-06-26 2019-06-26 10.34194/GEUSB-201943-02-02 Climate change: Sources of uncertainty in precipitation and temperature projections for Denmark https://geusbulletin.org/index.php/geusb/article/view/4222 <p>Global Climate Models (GCMs) are the main tools used to assess the impacts of climate change. Due to their coarse resolution, with cells of&nbsp;<em>c</em>. 100 km × 100 km, GCMs are dynamically downscaled using Regional Climate Models (RCMs) that better incorporate the local physical features and simulate the climate of a smaller region, e.g. a country. However, RCMs tend to have systematic biases when compared with local observations, such as deviations from day-to-day measurements, and from the mean and extreme events. As a result, confidence in the model projections decreases. One way to address this is to correct the RCM output using statistical methods that relate the simulations with the observations, producing bias-corrected (BC) projections.</p> <p>Here, we present the first assessment of a previously published method to bias-correct 21 RCM projections of daily temperature and precipitation for Denmark. We assess the projected changes and sources of uncertainty. The study provides an initial assessment of the bias correction procedure applied to this set of model outputs to adjust projections of annual temperature, precipitation and potential evapotranspiration (PET). This method is expected to provide a foundation for further analysis of climate change impacts in Denmark.</p> <p>&nbsp;</p> Ernesto Pasten-Zapata Torben O. Sonnenborg Jens Christian Refsgaard Copyright (c) 2019-06-24 2019-06-24 10.34194/GEUSB-201943-01-02 The channels in Storebælt, Denmark: implications of new radiocarbon ages https://geusbulletin.org/index.php/geusb/article/view/4295 <p>The brackish water Baltic Sea and the more saline Kattegat in the north are connected by three straits, Lillebælt, Storebælt and Øresund. Storebælt (the Great Belt) is the deepest and widest of the straits. The strait is characterised by deeply incised channels that are partly filled by sediments. The water depth in major parts of Storebælt is about 20 m, though in some areas the channels are more than 50 m deep.</p> <p>The formation of the channels has been subject to discussion. Andersen (1927) suggested that the channels formed due to strong currents that are still active today or by fluvial erosion during the so-called continental period (Fastlandstiden) in the Early Holocene. At this time, the relative sea level in the region was lower than at present and a huge lake, the Ancylus Lake, which occupied the Baltic Basin, may have drained via Storebælt. Andersen dismissed the idea that the channels were formed by subglacial erosion by meltwater during the last deglaciation. More Recently, Mathiassen (1997) interpreted some of the deposits in the channels as late glacial, a viewpoint followed by Bennike&nbsp;<em>et al.</em>&nbsp;(2004). However, the age of the late glacial deposits in the channels are poorly constrained.</p> <p>The first studies of sediment cores from Storebælt were carried out by Krog (1973), Winn (1974) and Mathiassen (1997), but these studies concentrated on the Holocene development from mires to lakes to brackish and marine environments. Wiberg-Larsen&nbsp;<em>et al.</em>&nbsp;(2001) documented the presence of Early Holocene river deposits. Here we report on some new ages of macrofossils from late glacial deposits in the Storebælt channels.</p> Ole Bennike Niels Nørgaard-Pedersen Jørn Bo Jensen Copyright (c) 2019-06-24 2019-06-24 10.34194/GEUSB-201943-01-06 Review of hydrocarbon potential in East Denmark following 30 years of exploration activities https://geusbulletin.org/index.php/geusb/article/view/4294 <p>Between 1993 and 2017, Denmark was one of the largest oil exporting countries in Europe having gained this position from its share in the highly prolific Danish Central Graben. However, outside the Central Graben few prospects have been adequately mapped, due to a lack of data in these socalled ‘white areas.’ As such, their potential for hydrocarbon accumulation remains uncertain. This paper presents an update of the prospect and play types in this area outside the Danish Central Graben, east of 6°15´E longitude (Fig. 1), based on results from the last 30 years of exploration activities. The paper is part of a resource assessment made by the Geological Survey of Denmark and Greenland (GEUS) to the Danish Energy Agency (Schovsbo &amp; Jakobsen 2017) and is an update of a former review of the area made in 1987 (Thomsen&nbsp;<em>et al</em>. 1987). The succeeding exploration efforts have not changed the overall low expectation for the play types in the area. Here, we show that an uncertain resource is associated with both the Zechstein carbonate play in the North German Basin and the Upper Triassic – Lower Jurassic sandstone and lower Palaeozoic shale gas plays in northern Jylland. However, questions remain as to the source of hydrocarbons in the western offshore area. Specifically, we are unable to confirm (or refute) whether these structures are sourced via long-distance migration of hydrocarbons from the Danish Central Graben.</p> <p>&nbsp;</p> Niels H. Schovsbo Finn Jakobsen Copyright (c) 2019-06-17 2019-06-17 10.34194/GEUSB-201943-01-05 Preliminary landslide mapping in Greenland https://geusbulletin.org/index.php/geusb/article/view/4301 <p>The landslide of 17 June 2017 in Karrat Fjord, central West Greenland, highlighted the need for a better understanding of landslides and landslide-generated tsunamis in Greenland and motivated a landslide screening project in 2018, led by the Geological Survey of Denmark and Greenland (GEUS; see also Svennevig&nbsp;<em>et al</em>. this volume). A central part of this project was to conduct a preliminary mapping of Quaternary and historical landslides in Greenland – the first effort of its kind. The main objective was to establish a landslide inventory database that can be used to identify areas prone to landslides and serve as a tool for gaining a better understanding of where, when and why catastrophic landslides take place in Greenland.</p> <p>This paper describes the workflow used to produce the preliminary landslide inventory of Greenland and discusses some of the initial results. To date (June 2019), I have mapped 564 landslides with the vast majority situated in the Nuussuaq Basin between Sigguup Nunaa (Svartenhuk Halvø), and Qeqertarsuaq (Disko) in West Greenland (Fig. 1). The inventory mapping is mainly based on observations and analyses of remotely sensed imagery and pre-existing geological maps. The mapping coverage was not systematic for all of Greenland, but focused on postglacial, potentially tsunamigenic landslides in inhabited coastal regions, i.e. on relatively large landslides on coastal slopes, mainly in West Greenland and small areas of East Greenland. However, smaller and inland landslides were included when they were encountered. Similarly, the less inhabited parts of Greenland were provisionally screened, but call for more thorough, systematic mapping in the future.</p> Kristian Svennevig Copyright (c) 2019-06-17 2019-06-17 10.34194/GEUSB-201943-02-07 Colophon, contents, preface https://geusbulletin.org/index.php/geusb/article/view/4306 <p>This bulletin presents a series of nine papers dealing with the succession of Upper Jurassic – Lower Cretaceous sedimentary rocks penetrated by the fully cored Blokelv-1 borehole, drilled in western Jameson Land, central East Greenland in August 2008. The borehole was drilled as the first of three boreholes that in combination were designed to provide full coverage of the Upper Jurassic – Lower Cretaceous petroleum source-rock succession in eastern Greenland. The remaining two boreholes, Rødryggen-1 and Brorson Halvø-1, were drilled on Wollaston Forland in 2009 and 2010, respectively, and the results from these boreholes will be published in a companion volume. The objectives of the drilling campaign were fulfilled, demonstrating that continuous sedimentation of oil-prone petroleum source rocks took place in eastern Greenland over a period of&nbsp;<em>c.&nbsp;</em>13 million years from the Oxfordian to the Ryazanian, with the Blokelv-1 succession representing the older, Oxfordian–Volgian part of this interval.</p> <p>The drilling campaign was carried out as one of a number of projects within the framework of a multi-client collaborative programme between GEUS and a long list of petroleum companies entitled&nbsp;<em>Petroleum Geological Studies, Services and Data in East and Northeast Greenland</em>. This collaboration was initiated in 2007 and is ongoing at the time of writing with more than 20 participant companies, a subset of which sponsored the studies presented herein; for contractual reasons, these companies cannot be named. The GEUS–industry collaboration was initiated in recognition of the need for new and better data on many aspects of the petroleum geology of eastern Greenland prior to an anticipated licensing round of offshore North-East Greenland. The&nbsp;<em>Circum-Arctic Resource Appraisal&nbsp;</em>(CARA), undertaken by the United States Geological Survey (USGS), also played an important role in defining the priorities of the collaborative agreement by directing attention towards specific subjects in need of investigation. Licensing rounds in 2012 and 2013 resulted in the award of five licences.</p> <p>Based on the results of these activities in eastern Greenland, a large number of scientific papers have been published since 2008, and more are expected as confidentiality clauses expire. This volume is, however, the first GEUS Bulletin to be published as a direct consequence of the GEUS–industry collaboration.</p> Jørgen A. Bojesen-Koefoed Copyright (c) 2018-12-28 2018-12-28 10.34194/geusb.v42.4306