GEUS Bulletin https://geusbulletin.org/index.php/geusb <p>GEUS Bulletin (eISSN: 2597-2154) is the current flagship journal published by the <a href="https://eng.geus.dk/" target="_blank" rel="noopener">Geological Survey of Denmark and Greenland (GEUS)</a>. Previously, the Geological Survey of Denmark and Greenland Bulletin (eISSN: 1904-4666). We are peer-reviewed and diamond open access. GEUS Bulletin publishes geoscience research papers, monographs and map descriptions for Denmark, Greenland and the Arctic region. We believe that open science benefits scientists, industry and society, so we do not charge publication fees and all our articles can be freely downloaded online. IF 2019: 0.680 5-year IF: 0.656</p> <p><strong>GEUS Bulletin is open for submissions to geoscientists whose research is focussed on Denmark, Greenland and the Arctic region. Read more in our <a href="https://geusbulletin.org/index.php/geusb/about">journal scope</a>.</strong></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> Estimating pesticides in public drinking water at the household level in Denmark https://geusbulletin.org/index.php/geusb/article/view/6090 <p><span style="color: #000000; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">Pesticide pollution has raised public concern in Denmark due to potential negative health impacts and frequent findings of new substances after a recent expansion of the groundwater monitoring programme. Danish drinking water comes entirely from groundwater. Both the raw groundwater and the treated drinking water are regularly monitored, and the chemical analyses are reported to a publicly available national database (Jupiter). Based on these data, in this study we (1) provide a status of pesticide content in drinking water supplied by public waterworks in Denmark and (2) assess the proportion of Danish households exposed to pesticides from drinking water. ‘Pesticides’ here refers also to their metabolites, degradation and reaction products. The cleaned dataset represents 3004 public waterworks distributed throughout the country and includes 39 798 samples of treated drinking water analysed for 449 pesticides (971 723 analyses total) for the period 2002–2019. Of all these chemical analyses, 0.5% (</span><em style="color: #000000; font-family: 'Times New Roman'; font-size: medium; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">n</em><span style="color: #000000; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;"> = 4925) contained a quantified pesticide (&gt;0.03 μg/l). Pesticides were found at least once in the treated drinking water at 29% of all sampled public waterworks for the period 2002–2019 and at 21% of the waterworks for the recent period 2015–2019. We estimate that 56% of all Danish households were potentially exposed at least once to pesticides in drinking water at concentrations of 0.03–4.00 μg/l between 2002 and 2019. However, in 2015–2019, the proportion of the Danish households exposed to pesticides (0.03–4.00 μg/l) was 41%. The proportion of Danish households potentially exposed at least once to pesticides above the maximum allowed concentration (0.1 μg/l) according to the EU Drinking Water Directive (and the Danish drinking water standard) was 19% for 2002–2019 and 11% for 2015–2019. However, the maximum concentrations were lower than the World Health Organization’s compound-specific guidelines. Lastly, we explore data complexity and discuss the limitations imposed by data heterogeneity to facilitate future epidemiological studies.</span></p> Denitza D. Voutchkova Jörg Schullehner Carina Skaarup Kirstine Wodschow Annette Kjær Ersbøll Birgitte Hansen Copyright (c) 2021 Denitza D. Voutchkova, Jörg Schullehner, Carina Skaarup, Kirstine Wodschow, Annette Kjær Ersbøll, Birgitte Hansen https://creativecommons.org/licenses/by/4.0 2021-04-12 2021-04-12 45 1 10.34194/geusb.v47.6090 Monitoring for seismological and geochemical groundwater effects of high-volume pumping of natural gas at the Stenlille underground gas storage facility, Denmark https://geusbulletin.org/index.php/geusb/article/view/5552 <p><span style="color: #000000; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">The large natural gas storage facility at Stenlille, Denmark, has been monitored to investigate the effect of pumping large amounts of gas into the subsurface. Here, we present a new dataset of microseismicity at Stenlille since 2018. We compare these data with methane in groundwater, which has been monitored since gas storage was established in 1989. Further, we conducted a controlled 172 day microcosm experiment of methane oxidation on an isolated microbial community under both aerobic and anaerobic conditions. For this experiment, water was filtered from a well at Stenlille with elevated levels of thermogenic methane and ethane. No microseismic activity was detected in the gas storage area above an estimated detection level of ML 0.0 for the established network. The long-term monitoring for methane in groundwater has still only detected one leak, in 1995, related to a technical problem during injection. The microcosm experiment revealed that oxidation of methane occurred only under aerobic conditions during the experiment, as compared to anaerobic conditions, even though the filtered water was anoxic</span></p> Trine Dahl-Jensen Rasmus Jakobsen Tina Bundgaard Bech Carsten Møller Nielsen Christian Nyrop Albers Peter H. Voss Tine B. Larsen Copyright (c) 2021 Trine Dahl-Jensen, Rasmus Jakobsen, Tina Bundgaard Bech, Carsten Møller Nielsen, Christian Nyrop Albers, Peter H. Voss, Tine B. Larsen https://creativecommons.org/licenses/by/4.0 2021-03-22 2021-03-22 45 1 10.34194/geusb.v47.5552 Middle Jurassic sandstone deposition in the Wandel Sea Basin: evidence from cardioceratid and kosmoceratid ammonites in the Mågensfjeld Formation in Kilen, North Greenland https://geusbulletin.org/index.php/geusb/article/view/5342 <p>Age assessments from both palynostratigraphy and macrofossil biostratigraphy of the sandstone-dominated Mågensfjeld Formation, Wandel Sea Basin, North Greenland were hitherto hampered by post-burial thermal degradation of dinoflagellate cysts and a lack of well-preserved macrofossils. The formation was previously assigned to the Upper Cretaceous based on erroneous fossil identifications. Finds of cardioceratid and kosmoceratid ammonites during recent field work now provide the first age control of the unit, demonstrating it to be of late Bajocian – late Bathonian and perhaps Callovian (Middle Jurassic) age. This makes it among the oldest Jurassic units, perhaps even Mesozoic units, recorded in Kilen, North Greenland and eastern North Greenland. Previously, the complex structural and tectonic evolution of the area was poorly understood, and the structural relation of the Mågensfjeld Formation to the surrounding Mesozoic units was a puzzle. The new age assessment simplifies the structural situation in the area significantly. Further, the inference of a large reverse fault previously required to explain the proximity of the Mågensfjeld Formation to neighbouring Jurassic units is now unnecessary. The data show that the Wandel Sea Basin was influenced by the Middle Jurassic transgression and had sufficient accommodation space for marine deposition earlier than previously thought. The unit serves as a key datapoint and analogue for possible Middle Jurassic units in adjacent offshore basins.</p> Peter Alsen Jussi Hovikoski Kristian Svennevig Copyright (c) 2020 Peter Alsen, Jussi Hovikoski, Kristian Svennevig https://creativecommons.org/licenses/by/4.0 2020-12-21 2020-12-21 45 1 10.34194/geusb.v44.5342 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 45 1 10.34194/geusb.v44.5302 Thermo-tectonic development of the Wandel Sea Basin, North Greenland https://geusbulletin.org/index.php/geusb/article/view/5298 <p><span style="color: #000000; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">The Carboniferous–Palaeogene Wandel Sea Basin of eastern North Greenland (north of 80°N, east of 40°W) is an important piece in the puzzle of Arctic geology. It is particularly important for understanding how the Paleocene–Eocene convergence between Greenland, the Canadian Arctic and Svalbard relates to the compressional tectonics in the High Arctic, collectively known as the Eurekan Orogeny. In this study, we present apatite fission-track analysis (AFTA) data and review published vitrinite reflectance data combined with observations from the stratigraphic record to place firmer constraints on the timing of key tectonic events. This research study reveals a long history of episodic burial and exhumation since the collapse of the Palaeozoic fold belts in Greenland. Our results define pre-Cenozoic exhumation episodes in early Permian, Late Triassic, Late Jurassic and mid-Cretaceous times, each involving the removal of kilometre-scale sedimentary covers. Mid-Paleocene exhumation defines the timing of compression along the major fault zones during the first stage of the Eurekan Orogeny, after the onset of sea-floor spreading west of Greenland. Regional exhumation that began at the end of the Eocene led to the removal of most of a kilometre-thick cover that had accumulated during Eocene subsidence and involved a major reverse movement along the Harder Fjord Fault Zone, northern Peary Land. These events took place after the end of sea-floor spreading west of Greenland, and thus, represent post-Eurekan tectonics. Mid–late Miocene exhumation is most likely a consequence of uplift and incision across most of the Wandel Sea Basin study area. The preserved sedimentary sequences of the Wandel Sea Basin represent remnants of thicker strata that likely extended substantially beyond the present-day outline of the basin. We find that the present-day outline of the basin with scattered sedimentary outliers is primarily the result of fault inversion during Eurekan compression followed by deposition and removal of a kilometre-thick overburden.</span></p> Peter Japsen Paul F. Green James A. Chalmers Copyright (c) 2021 Peter Japsen, Paul F. Green, James A. Chalmers https://creativecommons.org/licenses/by/4.0 2021-04-26 2021-04-26 45 1 10.34194/geusb.v45.5298 Peneplains and tectonics in North-East Greenland after opening of the North-East Atlantic https://geusbulletin.org/index.php/geusb/article/view/5297 <p>Elevated plateaus with deeply incised valleys characterise elevated, passive continental margins (EPCMs) in all climate zones. These features are, however, a topic of debate regarding when and how the large-scale landscapes formed. We have investigated and mapped the partly glaciated landscape of North-East Greenland (70–78°N). The area consists of crystalline basement and Palaeozoic–Mesozoic rift basins, capped by Palaeogene basalts that erupted during the northeast Atlantic break-up. Our stratigraphic landscape analysis reveals a typical EPCM dominated by two elevated erosion surfaces, extending 200 km east–west and 900 km north–south. The low-relief Upper Planation Surface (UPS; c. 2 km above sea level) cuts across basement and Palaeogene basalts, indicating that it was graded to base level defined by the Atlantic Ocean in post-basalt times and subsequently uplifted. The UPS formed prior to the deposition of mid-Miocene lavas that rest on it, south of the study area. In the interior basement terrains, the Lower Planation Surface (LPS) forms fluvial valley benches at c. 1 km above sea level, incised below the UPS. The LPS is thus younger than the UPS, which implies that it formed post mid-Miocene. Towards the coast, the valley benches merge to form a coherent surface that defines flat-topped mountains. This shows that the LPS was graded to near sea level and was subsequently uplifted. Hence, both the UPS and the LPS formed as peneplains – erosion surfaces graded to base level. The fluvial valley benches associated with the LPS further indicates that full glacial conditions were only established after the uplift of the LPS in the early Pliocene (c. 5 Ma). The uplift of the LPS led to re-exposure of a Mesozoic etch surface. We conclude that episodes of late Neogene tectonic uplift shaped the stepped landscape and elevated topography in North-East Greenland.</p> Johan M. Bonow Peter Japsen Copyright (c) 2021 Johan M. Bonow, Peter Japsen https://creativecommons.org/licenses/by/4.0 2021-01-21 2021-01-21 45 1 10.34194/geusb.v45.5297 Greenland bare-ice albedo from PROMICE automatic weather station measurements and Sentinel-3 satellite observations https://geusbulletin.org/index.php/geusb/article/view/5284 <p><span style="font-weight: 400;"><span style="color: #000000; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) provides surface meteorological and glaciological measurements from widespread on-ice automatic weather stations since mid-2007. In this study, we use 105 PROMICE ice-ablation time series to identify the timing of seasonal bare-ice onset preceded by snow cover conditions. From this collection, we find a bare-ice albedo at ice-ablation onset (here called bare-ice-onset albedo) of 0.565 ± 0.109 that has no apparent spatial dependence among 20 sites across Greenland. We then apply this snow-to-ice albedo transition value to measure the variations in daily Greenland bare-ice area in Sentinel-3 optical satellite imagery covering the extremely low and high respective melt years of 2018 and 2019. Daily Greenland bare-ice area peaked at 153 489 km² in 2019, 1.9 times larger than in 2018 (80 220 km²), equating to 9.0% (in 2019) and 4.7% (in 2018) of the ice sheet area.</span></span></p> Adrien Wehrlé Jason E. Box Masashi Niwano Alexandre M. Anesio Robert S. Fausto Copyright (c) 2021 Adrien Wehrlé, Jason E. Box, Masashi Niwano, Alexandre M. Anesio, Robert S. Fausto https://creativecommons.org/licenses/by/4.0 2021-04-19 2021-04-19 45 1 10.34194/geusb.v47.5284 Review of Survey activities: Colophon, contents, introduction https://geusbulletin.org/index.php/geusb/article/view/5254 Flemming G. Christiansen Copyright (c) 0 2017-07-31 2017-07-31 45 1 1 8 10.34194/geusb.v38.5254 Structural analysis of the Rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark https://geusbulletin.org/index.php/geusb/article/view/5253 <p>Pedersen, S.A.S. 2005: Structural analysis of the Rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark. <em>Geological Survey of Denmark and Greenland Bulletin 8, 192 pp</em>.</p> <p>The Rubjerg Knude Glaciotectonic Complex is a thin-skinned thrust-fault complex that was formed during the advance of the Scandinavian Ice Sheet (30 000 – 26 000 B.P.); it is well exposed in a 6 km long coastal profile bordering the North Sea in northern Denmark. The glaciotectonic thrust-fault deformation revealed by this cliff section has been subjected to detailed structural analysis based on photogrammetric measurement and construction of a balanced cross-section. Thirteen sections are differentiated, characterising the distal to proximal structural development of the complex. The deformation affected three stratigraphic units: the Middle Weichselian arctic marine Stortorn Formation, the mainly glaciolacustrine Lønstrup Klint Formation and the dominantly fluvial Rubjerg Knude Formation; these three formations are formally defined herein, together with the Skærumhede Group which includes the Stortorn and Lønstrup Klint Formations. The Rubjerg Knude Formation was deposited on a regional unconformity that caps the Lønstrup Klint Formation and separates pre-tectonic deposits below from syntectonic deposits above.</p> <p>In the distal part of the complex, the thrust-fault architecture is characterised by thin flatlying thrust sheets displaced over the footwall flat of the foreland for a distance of more than 500 m. Towards the proximal part of the complex, the dip of the thrust faults increases, and over long stretches they are over-steepened to an upright position. The lowest décollement zone is about 40 m below sea level in the proximal part of the system, and shows a systematic step-wise change to higher levels in a distal (southwards) direction. The structural elements are ramps and flats related to hanging-wall and footwall positions. Above upper ramp-hinges, hanging-wall anticlines developed; footwall synclines are typically related to growth-fault sedimentation in syntectonic piggyback basins, represented by the Rubjerg Knude Formation. Blocks and slump-sheets constituting parts of the Lønstrup Klint Formation were derived from the tips of up-thrusted thrust sheets and slumped into the basins. Mud diapirs are a prominent element in the thrust-fault complex, resulting from mud mobilisation mainly at hanging-wall flats and ramps.</p> <p>Shortening during thrust-fault deformation has been calculated as 50%. Only about 11% of the initial stratigraphic units subjected to thrust faulting has been lost due to erosion. The thrust-fault deformation was caused by gravity spreading of an advancing ice sheet. Overpressured mud-fluid played an important role in stress transmission. The average velocity of thrust-fault displacement is estimated at 2 m per year, which led to compression of a 12 km stretch of flat-lying sediments, c. 40 m in thickness, into a thrust-fault complex 6 km in length. The thrust-fault complex is truncated by a glaciotectonic unconformity, formed when the advancing ice sheet finally overrode the complex. When this ice sheet melted away, a hilland- hole pair was formed, and meltwater deposits derived from a new ice-advance (NE-Ice) filled the depression. The NE-Ice overran the complex during its advance to the main stationary line situated in the North Sea. When this ice in turn melted away (c. 19 000 – 15 000 B.P.), the glacial landscape was draped by arctic marine deposits of the Vendsyssel Formation (new formation defined herein).</p> Stig A. Schack Pedersen Copyright (c) 0 2005-12-15 2005-12-15 45 1 1 192 10.34194/geusb.v8.5253 Lithostratigraphy of the Palaeogene – Lower Neogene succession of the Danish North Sea https://geusbulletin.org/index.php/geusb/article/view/5249 <p>As a result of a lithological, sedimentological and biostratigraphic study of well sections from the Danish sector of the North Sea, including some recently drilled exploration wells on the Ringkøbing–Fyn High, the lithostratigraphic framework for the siliciclastic Palaeogene to Lower Neogene sediments of the Danish sector of the North Sea is revised. The sediment package from the top of the Chalk Group to the base of the Nordland Group is subdivided into seven formations containing eleven new members. The existing Våle, Lista, Sele, Fur, Balder, Horda and Lark Formations of previously published lithostratigraphic schemes are adequate for a subdivision of the Danish sector at formation level. Bor is a new sandstone member of the Våle Formation. The Lista Formation is subdivided into three new mudstone members: Vile, Ve and Bue, and three new sandstone members: Tyr, Idun and Rind. Kolga is a new sandstone member of the Sele Formation. Hefring is a new sandstone member of the Horda Formation. Freja and Dufa are two new sandstone members of the Lark Formation. Danish reference sections are established for the formations, and the descriptions of their lithology, biostratigraphy, age and palaeoenvironmental setting are updated.</p> Poul Schiøler Jan Andsbjerg Ole R. Clausen Gregers Dam Karen Dybkjær Lars Hamberg Claus Heilmann-Clausen Erik P. Johannessen Lars E. Kristensen Iain Prince Jan A. Rasmussen Copyright (c) 0 2007-06-29 2007-06-29 45 1 1 77 10.34194/geusb.v12.5249 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 45 1 10.34194/geusb.v44.5240 Fully automated analysis of grain chemistry, size and morphology by CCSEM: examples from cement produc tion and diamond exploration https://geusbulletin.org/index.php/geusb/article/view/5053 <p>Computer-controlled scanning electron microscopy (CCSEM) combines the advantages of energy dispersive X-ray spectrometry (EDX) with those of digital image analysis of back-scattered electron (BSE) micrographs. CCSEM analysis of a wide range of geological or non-geological materials has been introduced at the Geological Survey of Denmark and Greenland (GEUS) as a fast and reliable method to determine both the chemistry of individual grains and bulk samples. The chemical analysis is combined with measurements of the two-dimensional size and morphology of every single grain. The CCSEM technique was developed in the early 1980s for characterisation of coal minerals (Huggins <em>et al.</em> 1980; Lee &amp; Kelly 1980) and studies of synthetic crystals for super-conductors and catalysts (Lin &amp; Barnes 1984). Soon it found a broader application in the study of dust particles and fibres in lung tissue of mine workers (Friedrichs 1987), in the analyses of aerosols for air quality control and source emission characterisation (e.g. Heasman &amp; Watt 1989) and the degree of sintering and consolidation of coal ash deposits (e.g. Huffman <em>et al.</em> 1994). CCSEM has been used in the earth sciences for the determination of the sediment budget of a lake (Yin &amp; Johnson 1984), for the characterisation of soil and dust (Pirrie <em>et al.</em> 2004), for provenance analysis of ilmenite-bearing beach sands (Knudsen <em>et al.</em> 2005; Bernstein <em>et al.</em> 2008), and provenance studies on sandstones in oil-bearing basins (Frei <em>et al.</em> 2005). Other areas where CCSEM has been applied range widely and include characterisation of small inclusions, e.g. impurities in metal alloys or steel (Schwoeble <em>et al.</em> 1988), analyses of gun-shot residues (e.g. Steffen <em>et al.</em> 2007), and analyses of bladder stones obtained from a skeleton found in a Mesolithic cave-tomb (D’Alessio <em>et al.</em> 2005). In this paper, we demonstrate the benefits of the method with examples from the cement industry and from diamond prospecting.</p> Nynke Keulen Dirk Frei Stefan Bernstein Mark T. Hutchison Christian Knudsen Lucas Jensen Copyright (c) 2008-07-10 2008-07-10 45 1 93 96 10.34194/geusb.v15.5053 Laser ablation analysis of bivalve shells – archives of environmental information https://geusbulletin.org/index.php/geusb/article/view/5052 <p>Reconstructing past secular environmental variations is an important issue in palaeoclimate research. However, most key variables for palaeoclimate reconstructions cannot be measured directly, and reconstructions are therefore based on proxy data. Here, we demonstrate the potential of bivalve shells as an archive of environmental parameters. The Geological Survey of Denmark and Greenland (GEUS) has developed a fast and reliable method for chemical analyses of shell material by laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS), and here we present some examples of the use of this method. In tropical and subtropical waters, corals can provide century-long archives of past water chemistry with annual resolution. A comparable archive for temperate and Arctic waters would be highly useful in climate research, and therefore it has been examined whether this can be provided by bivalve shells (e.g. Schoene <em>et al.</em> 2005). Long-lived species may provide archives with annual resolution extending over several hundred years, whereas short-lived, fast-growing species can provide archives with a seasonal or in some cases daily resolution over a period of a few years. Most bivalves are sessile, and shells are commonly preserved as fossils. There are, however, a number of challenges related to the use of bivalves as proxy archives: (1) many proxies show species specific behaviour (Seed 1980); (2) only very few proxies are dependent on a single variable (Wefer <em>et al.</em> 1999); and (3) the effects of biology and ontogeny on the uptake of trace elements and stable isotope fractionation in shell carbonate are largely unknown and have to be evaluated empirically. Therefore, any potential proxy must be calibrated individually for each species of interest before it can be used. A large number of chemical analyses are needed to calibrate a proxy. These are commonly obtained by solution ICP-MS, in which sample preparation is time-consuming and labour-intensive. The use of LA-ICP-MS is therefore a considerable advance in bivalve shell proxy research, as it greatly reduces the effort needed for sample preparation. At the same time, the method requires less material for analysis, thus providing better spatial and hence temporal resolution. Proxies based on bivalve shell carbonate can be used in present-day environmental monitoring, and for environmental reconstructions from shells found as fossils. Shells from museum collections and shells found in archaeological middens can give information on historic and prehistoric environmental conditions (e.g. Carrell <em>et al.</em> 1987), and fossil shells can be used as archives of environmental parameters on geological timescales (e.g. Hendry <em>et al.</em> 2001).</p> Maiken Hansen Klünder Dorothee Hippler Rob Witbaard Dirk Frei Copyright (c) 2008-07-10 2008-07-10 45 1 89 92 10.34194/geusb.v15.5052 KenSea – tsunami damage modelling for coastal areas of Kenya https://geusbulletin.org/index.php/geusb/article/view/5051 <p>On 26 December 2004, the eastern part of the Indian Ocean was hit by a tremendous tsunami created by a submarine earthquake of magnitude 9.1 on the Richter scale off the west coast of Sumatra. The tsunami also reached the western part of the Indian Ocean, including the coastal areas of eastern Africa. Along the coast of Kenya (Figs 1, 2) it resulted in a sudden increase in water level comparable to a high tide situation. This rather limited consequence was partly due to the great distance to the epicentre of the earthquake, and partly due to the low tide at the time of the impact. Hence the reefs that fringe two thirds of the coastline reduced the energy of the tsunami waves and protected the coastal areas. During the spring of 2005, staff members from the Geological Survey of Denmark and Greenland (GEUS) carried out field work related to the project KenSea – development of a sensitivity atlas for coastal areas of Kenya (Tychsen 2006; Tychsen <em>et al.</em> 2006). Local fishermen and authorities often asked what would have been the effect if the tsunami had hit the coastal area during a high tide, and to answer the question GEUS and the Kenya Marine and Fisheries Research Institute (KMFRI) initiated a tsunami damage projection project. The aim was to provide an important tool for contingency planning by national and local authorities in the implementation of a national early warning strategy. The tsunami damage projection project used the database of coastal resources – KenSeaBase – that was developed during the KenSea project. The topographical maps of Kenya at a scale of 1:50 000 have 20 m contour lines, which is insufficient for the tsunami run-up simulation modelling undertaken by the new tsunami project. Therefore new sets of aerial photographs were obtained, and new photogrammetric maps with contour lines with an equidistance of 1 m were drawn for a 6–8 km broad coastal zone. The tsunami modelling is based on the assumption that the height of a future tsunami wave would be comparable with the one that reached the coastal area of Kenya in December 2004. Based on the regional geology of the Indian Ocean, it appears that the epicentre for a possible future earthquake that could lead to a new tsunami would most likely be situated in the eastern part of the ocean. Furthermore, based on a seismological assessment it has been estimated that the largest tsunami that can be expected to reach eastern Africa would have a 50% larger amplitude than the 2004 tsunami. It was therefore decided to carry out the simulation modelling with a tsunami wave similar to that of the 2004 event, but with the wave reaching the coast at the highest astronomical tide (scenario 1) and a worst case with a 50% larger amplitude (scenario 2: Fig. 3). The 2004 tsunami documented that the coastal belt of mangrove swamps provided some protection to the coastline by reducing the energy of the tsunami. Hence we included in this study a scenario 3 (Fig. 4), in which the mangrove areas along the coastline were removed. Maps for the three scenarios have been produced and show the areas that would be flooded, the degree of flooding, and the distribution of buildings such as schools and hospitals in the flooded areas. In addition, the force and velocity of the wave were calculated (COWI 2006).</p> John Tychsen Ole Geertz-Hansen Frands Schjøth Copyright (c) 2008-07-10 2008-07-10 45 1 85 88 10.34194/geusb.v15.5051 From science to practice in implementing the European Union’s Water Framework Directive https://geusbulletin.org/index.php/geusb/article/view/5050 <p>The Water Framework Directive (WFD) of the European Union aims to achieve a ‘good’ status for all inland and coastal waters by the year 2015 (EC 2000). The directive defines how this should be achieved through the establishment of environmental objectives and ecological targets. Successful implementation of the WFD requires integration into already existing national legislation and a sound combination of issues on technical feasibility, scientific knowledge and socio-economic aspects requiring intensive stakeholder involvement. This calls for appropriate tools such as models to support management of technical and social aspects of different phases of the implementation (Rekolainen <em>et al.</em> 2003; Quevauviller <em>et al.</em> 2005). It is therefore necessary to provide an overview of already existing methods and tools and develop new ones. Research programmes funded by the European Commission (EC) often address issues of current interest for practitioners, such as the Fifth Framework Programme, where a number of research projects to support the practical implementation of the WFD were initiated under the theme ‘Energy, Environment and Sustainable Development’. The funding part (the Directorate-General for Research, DG Research) and the responsible authority for the WFD at European level (Directorate-General of Environment) saw the need to cluster these research projects and related activities, and initiated the Harmoni-CA project, a socalled ‘Concerted Action’ (i.e. Harmonised Modelling Tools for Integrated River Basin Management). The objectives of this paper are (a) to briefly describe the overall purpose of the Harmoni-CA project and some of its overarching outputs, and (b) to further illustrate how the implementation of the WFD can be enhanced by combining monitoring and modelling disciplines and by bringing practitioners and researchers together.</p> Lisbeth Flindt Jørgensen Jens Christian Refsgaard Anker Lajer Højberg Copyright (c) 2008-07-10 2008-07-10 45 1 81 84 10.34194/geusb.v15.5050 Hans Ø, celebrated island of Nares Strait between Greenland and Canada: from dog-sledge to satellite mapping https://geusbulletin.org/index.php/geusb/article/view/5049 <p>Hans Ø – or Tartupaluk to the indigenous population of North-West Greenland – is a small steeply sided island in Nares Strait at <em>c.</em> 80°50´N. Charted in 1871 and named after Greenlander Hans Hendrik, it is one of five limestone islands forming an integral part of the Greenland Silurian succession. Rising less than 170 m above normally ice-infested waters, the 1.25 km<sup>2</sup> island is physiographically far overshadowed by nearby Franklin Ø (Fig. 1). The island’s notoriety results from its placing more or less equidistant between the coasts of Kennedy Channel on the political boundary between Greenland and Canada. For 40 years the rocky patch has been the subject of a dispute be tween the Danish/Greenland and Canadian governments regarding sovereignty rights, an issue that remains unresolved. However, there is mutual understanding between Canada and Denmark that “since the question of sovereignty over the island has not yet been solved no action should be taken by either side which might prejudge the settlement of the issue” (Brückner 1984). Formally, this remains the position today.</p> Peter R. Dawes Tapani Tukiainen Copyright (c) 2008-07-10 2008-07-10 45 1 77 80 10.34194/geusb.v15.5049 New zircon ages from the Tasiusarsuaq terrane, southern West Greenland https://geusbulletin.org/index.php/geusb/article/view/5048 <p>In the last three field seasons the Geological Survey of Denmark and Greenland (GEUS) has undertaken mapping in the south-eastern part of the Nuuk region in southern West Greenland, and here we present new zircon ages that help constrain the northern boundary of the Tasiusarsuaq terrane. The Archaean geology of the Nuuk region is commonly interpreted as a tectonic collage assembled through lateral accretion and collision of oceanic and continental slivers and blocks (e.g. Friend &amp; Nutman 2005). Popular jargon describes these as terranes, bounded by faults or mylonite zones and characterised by rocks of contrasting origin on either side of their tectonic boundaries (Coney <em>et al.</em> 1980). The Isukasia and Færingehavn terranes (Figs 1, 2) are the oldest terranes at ≥3.75 Ga, and extend from the outer part of Godthåbsfjord in the south-west to the margin of the Inland Ice in the north-east, but they might not have a common geological history (Friend &amp; Nutman 2005). The Tre Brødre terrane is mainly represented by the Ikkatoq gneiss and occurs in close spatial relationship with the Færingehavn terrane, and also as a pronounced thrust unit along the Qarliit Nunaat thrust between the Færingehavn and Tasiusarsuaq terranes (Fig. 1; Nutman <em>et al.</em> 1989). The terrane boundaries in the inner fjord region near the Inland Ice margin are less well constrained; the Tre Brødre terrane extends into the region from the south-west, the Kapisilik terrane is defined from the northern and eastern part and borders the Tasiusarsuaq terrane to the south and possibly to the east. The terrane accretion is believed to have taken place in two events. The first terrane accretion is defined from the northern part of the region, and possibly involves the Isukasia, Kapisilik and Akia terranes. The thermal event stitching these terranes is dated to <em>c.</em> 2.99–2.95 Ga (Fig. 2; Hanmer <em>et al.</em> 2002; Friend &amp; Nutman 2005). The second accretion phase of the major continental blocks is believed to have occurred at around 2.725–2.71 Ga. This second event is well described, and includes anatexis and emplacement of continental crust-derived granites, which are associated with contemporaneous metamorphism (Friend <em>et al.</em> 1996). Figure 2 outlines regional plutonic, metamorphic and supracrustal events. Individual terranes were formed during relatively short time periods with active geological processes of creation and recycling of continental crust, and most of the terranes follow a similar pattern of development. The first plutonic events consisted of primitive magmas and produced tonalite–trondhjemite–granodiorite (TTG) and dioritic gneisses. Younger, more evolved granitic magmas were often intruded simultaneously with high-grade metamorphism. This development may reflect a stabilisation of the individual terranes.</p> Tomas Næraa Anders Scherstén Copyright (c) 2008-07-10 2008-07-10 45 1 73 76 10.34194/geusb.v15.5048 Geochemistry of greenstones in the Tasiusarsuaq terrane, southern West Greenland https://geusbulletin.org/index.php/geusb/article/view/5047 <p>Tonalite-trondhjemite–granodiorite (TTG) gneisses and melanocratic to ultramafic greenstones dominate the Archaean basement of southern West Greenland. The greenstones are likely to represent different original environments, which is important as the mineral deposits they may host depend on this. For example, massive sulphide deposits associated with gold and base metals are commonly volcanogenic, while chrome, nickel and platinum group elements are more commonly associated with layered intrusions (Robb 2005). Current investigations by the Geological Survey of Denmark and Greenland (GEUS) in southern West Greenland are therefore focused on the origin of greenstones and their relationship to associated TTG gneisses. Here, we report on work in progress on greenstones within the Tasiusarsuaq terrane (Fig. 1; Friend <em>et al.</em> 1996). They differ from many other greenstone belts in southern West Greenland in their spatial association with the TTG gneisses. Unlike the Isua, Ivisârtoq and Storø greenstone belts in the central and northern Nuuk region, the Tasiusarsuaq greenstones are not proximal to terrane boundaries but form dismembered blocks and slivers within the terrane (Fig. 1). Contact relationships to the gneisses are almost exclusively tectonic, and primary textures are, with rare exceptions, obliterated by amphibolite to granulite facies metamorphism.</p> Anders Scherstén Henrik Stendal Tomas Næraa Copyright (c) 2008-07-10 2008-07-10 45 1 69 72 10.34194/geusb.v15.5047 The north-east Baffin Bay region, offshore Greenland – a new frontier petroleum exploration region https://geusbulletin.org/index.php/geusb/article/view/5046 <p>In recent years the Arctic has come into focus for hydrocarbon exploration, and areas offshore both West and East Greenland have been evaluated as promising frontier hydrocarbon provinces. Seven hydrocarbon exploration and exploitation licenses were awarded in 2007–2008 offshore the Disko–Nuussuaq region (Fig. 1), and two more have been awarded in the open-door region offshore south-western Greenland. In 2007, an extensive amount of new seismic and aeromagnetic data was acquired by the TGS-NOPEC Geophysical Company in the north-eastern Baffin Bay region. Geophysical mapping has been initiated by the Geological Survey of Denmark and Greenland (GEUS) in the Melville Bugt region offshore North-West Greenland (Fig. 1) with the purpose of evaluating the hydrocarbon prospectivity. Initial interpretation of seismic and gravity data suggests the presence of deep sedimentary basins separated by structural highs. Geological information on source rock, reservoir rock and seal intervals from surrounding regions suggest that the Melville Bugt region is likely to have a significant petroleum potential. The study is based on public domain magnetic and gravity data, and all proprietary and public 2-D seismic data (Fig. 1) acquired before 2003. Seismic horizons from the ‘seismic basement’ to ‘base Quaternary’ are being interpreted regionally. Based on the seismic interpretation, a structural element map, depth-structure maps and isopach maps will be produced in order to assess the prospectivity of the Melville Bugt region.</p> Ulrik Gregersen Copyright (c) 2008-07-10 2008-07-10 45 1 65 68 10.34194/geusb.v15.5046 A new programme for monitoring the mass loss of the Greenland ice sheet https://geusbulletin.org/index.php/geusb/article/view/5045 <p>The Greenland ice sheet has been losing mass at a dramatic rate in recent years, raising political concern worldwide due to the possible impact on global sea level rise and climate dynamics (Luthcke <em>et al.</em> 2006; Rignot &amp; Kanagaratnam 2006; Velicogna &amp; Wahr 2006; IPCC 2007; Shepherd &amp; Wingham 2007). The Arctic region as a whole is warming up much more rapidly than the globe at large (ACIA 2005) and it is desirable to quantify these changes in order to provide the decision-makers with a firm knowledge base. To cover this need, the Danish Ministry of Climate and Energy has now launched a new Programme for Monitoring of the Greenland Ice Sheet (PROMICE), designed and operated by the Geological Survey of Denmark and Greenland (GEUS) in collaboration with the National Space Institute at the Technical University of Denmark and Asiaq (Greenland Survey). The aim of the programme is to quantify the annual mass loss of the Greenland ice sheet, track changes in the extent of local glaciers and ice caps, and track changes in the position of the ice-sheet margin.</p> Andreas P. Ahlstrøm * PROMICE project team Copyright (c) 2008-07-10 2008-07-10 45 1 61 64 10.34194/geusb.v15.5045 Environmental response to the cold climate event 8200 years ago as recorded at Højby Sø, Denmark https://geusbulletin.org/index.php/geusb/article/view/5044 <p>The need for accurate predictions of future environmental change under conditions of global warming has led to a great interest in the most pronounced climate change known from the Holocene: an abrupt cooling event around 8200 years before present (present = A.D. 1950), also known as the ‘8.2 ka cooling event’ (ka = kilo-annum = 1000 years). This event has been recorded as a negative δ<sup>18</sup>O excursion in the central Greenland ice cores (lasting 160 years with the lowest temperature at 8150 B.P.; Johnsen <em>et al.</em> 1992; Dansgaard 1993; Alley <em>et al.</em> 1997; Thomas <em>et al.</em> 2007) and in a variety of other palaeoclimatic archives including lake sediments, ocean cores, speleothems, tree rings, and glacier oscillations from most of the Northern Hemisphere (e.g. Alley &amp; Ágústsdóttir 2005; Rohling &amp; Pälike 2005). In Greenland the maximum cooling was estimated to be 6 ± 2°C (Alley <em>et al.</em> 1997) while in southern Fennoscandia and the Baltic countries pollenbased quantitative temperature reconstructions indicate a maximum annual mean temperature decrease of around 1.5°C (e.g. Seppä <em>et al.</em> 2007). Today there is a general consensus that the primary cause of the cooling event was the final collapse of the Laurentide ice sheet near Hudson Bay and the associated sudden drainage of the proglacial Lake Agassiz into the North Atlantic Ocean around 8400 B.P. (Fig. 1; Barber <em>et al.</em> 1999; Kleiven <em>et al.</em> 2008). This freshwater outflow, estimated to amount to <em>c.</em> 164,000 km<sup>3</sup> of water, reduced the strength of the North Atlantic thermohaline circulation and thereby the heat transported to the North Atlantic region, resulting in an atmospheric cooling (Barber <em>et al.</em> 1999; Clark <em>et al.</em> 2001; Teller <em>et al.</em> 2002). The climatic consequences of this meltwater flood are assumed to be a good geological analogue for future climate-change scenarios, as a freshening of the North Atlantic is projected by almost all global-warming models (e.g. Wood <em>et al.</em> 2003; IPCC 2007) and is also currently being registered in the region (Curry <em>et al.</em> 2003). In an ongoing project, the influence of the 8.2 ka cooling event on a Danish terrestrial and lake ecosystem is being investigated using a variety of biological and geochemical proxy data from a sediment core extracted from Højby Sø, north-west Sjælland (Fig. 2). Here we present data on changes in lake hydrology and terrestrial vegetation in response to climate change, inferred from macrofossil data and pollen analysis, respectively.</p> Peter Rasmussen Mikkel Ulfeldt Hede Nanna Noe-Nygaard Annemarie L. Clarke Rolf D. Vinebrooke Copyright (c) 2008-07-10 2008-07-10 45 1 57 60 10.34194/geusb.v15.5044 Evidence of stretching of the lithosphere under Denmark https://geusbulletin.org/index.php/geusb/article/view/5043 <p>The structure of the lithosphere under Denmark has been investigated in relation to adjacent regions of Sweden and Germany. The most interesting result of the study is that the 120 km thick lithosphere under Denmark appears to be a stretched version of the Swedish lithosphere, which is more than twice as thick. During the international project Teleseismic Tomography across the Tornquist Zone (Tor), field work and international interpretation were carried out between 1996 and 2002. Following the field work period, model velocity computations were undertaken based on observations of distant earthquakes (e.g. Arlitt 1999; Shomali <em>et al.</em> 2002; Voss<em> et al.</em> 2006), and recently an evaluation of the Tor results was completed (Nielsen 2007). The Tor project investigates deeper parts of the Earth than previous projects, and in particular the depth interval 50–300 km, which is below the crystalline crust. The investigations have included many geophysical features such as teleseismic P-wave tomography, Rayleigh wave velocities, shear wave splitting and wave scattering. We have distinguished between relatively high- and low-velocity zones, which also show variations in anisotropy and scatter characteristics. Generalised high-velocity zones correspond to the lithosphere, while generalised relatively low-velocity zones are equivalent to the asthenosphere. The main outcome of the combined studies is that the deep lithosphere can be divided into three blocks separated approximately along the national boundaries between Sweden and Denmark and between Denmark and Germany. The boundaries between the blocks are steep, almost vertical. The Denmark block has lithosphere properties between those to the north and south. Based on previous crustal studies and the Tor results, we suggest that the Denmark block has evolved by stretching. The details in the new evaluation are derived from teleseismic tomography. Here we present a synthesis of the many derived models in the light of the new evaluation.</p> Søren Gregersen Lene Vandur Nielsen Peter Voss Copyright (c) 2008-07-10 2008-07-10 45 1 53 56 10.34194/geusb.v15.5043 Sedimentary facies and architecture of the Holocene to Recent Rømø barrier island in the Danish Wadden Sea https://geusbulletin.org/index.php/geusb/article/view/5042 <p>This paper describes an ongoing multidisciplinary study on the development of the barrier islands in the Danish Wadden Sea (Vadehavet), carried out by the Department of Geography and Geology at the University of Copenhagen and the Geolo gical Survey of Denmark and Greenland (GEUS). Nine sediment cores each <em>c.</em> 25 m long and a total of <em>c.</em> 45 km ground penetrating radar (GPR) profiles have been acquired on the islands of Rømø and Fanø. Geochemical and palaeontological analyses and dating of 150 core samples using optically stimulated luminescence (OSL) are in progress. This multidisciplinary approach has given new insights into the sedimentary architecture and development of the island, and the study is expected to result in a new detailed facies model. Such models are essential for an assessment of the effects of rising sea level associated with global warming. The new facies model can also be used as an analogue for subsurface oil or water reservoirs in similar sedimentary settings. This article presents selected core and GPR data from the Rømø barrier island.</p> Peter N. Johannessen Lars Henrik Nielsen Lars Nielsen Ingelise Møller Morten Pejrup Thorbjørn J. Andersen Joakim Korshøj Birger Larsen Stefan Piasecki Copyright (c) 2008-07-10 2008-07-10 45 1 49 52 10.34194/geusb.v15.5042 Use of geochemistry in groundwater vulnerability mapping in Denmark https://geusbulletin.org/index.php/geusb/article/view/5041 <p>The principal aim of mapping ground-water vulnerability in Denmark is to ensure optimal protection of present and future drinking-water resources. Groundwater vulnerability mapping of areas up to 1000 km<sup>2</sup> has been taking place over the past seven years. The scale of mapping has been adjusted to meet the demands for details of regulation of land use requested by Danish legislation. Groundwater vulnerability mapping comprises analyses and integration of geological, geophysical, hydrological and geochemical data. This paper focuses on the geochemical reactions between groundwater and sediment. Geochemical knowledge may sometimes not be fully and systematically utilised in groundwater vulnerability mapping. This paper presents different geochemical approaches and demonstrates how these can be successfully integrated with geological, geophysical and hydrological data.</p> Birgitte Hansen Lærke Thorling Copyright (c) 2008-07-10 2008-07-10 45 1 45 48 10.34194/geusb.v15.5041 Geology of outer Horns Rev, Danish North Sea https://geusbulletin.org/index.php/geusb/article/view/5040 <p>In 2006, Dong Energy initiated the development of the Horns Rev II offshore wind farm in the North Sea (Fig. 1). In order to evaluate and map the characteristics of the surface features of the sea bed and to characterise the subsurface in the wind farm area, the Geological Survey of Denmark and Greenland (GEUS) conducted a geophysical survey of the area. The survey utilised a variety of instruments: sparker, side-scan sonar, marine caesium magnetometer and a multibeam echo-sounder. In addition, information on the subsurface sediments was obtained by cone penetration tests (CPT) and by drilling to 30–50 m below the sea bottom. Geological correlation of the CPT results with the other survey results was extremely complicated but was required in order to understand the architecture of the ice marginal glaciotectonic complex. Information on the geology is crucial for evaluation of the geotechnical problems of the region.</p> Jørn Bo Jensen Peter Gravesen Steen Lomholt Copyright (c) 0 2008-07-10 2008-07-10 45 1 41 44 10.34194/geusb.v15.5040