GEUS Bulletin (Geological Survey of Denmark and Greenland)
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Diagenetic impact on reservoir sandstones of the Heno Formation in the Ravn-3 well, Danish Central Graben
No full textOil and gas production from siliciclastic reservoirs has hitherto been in the Danish Central Graben mostly from Palaeogene and Middle Jurassic sandstone. The Ravn field was the first Upper Jurassic field to start operation. The reservoir is composed of sandstone of the Heno Formation. Production takes place at a depth of 4000 m, which makes Ravn the deepest producing field in the Danish North Sea. The Heno Formation mainly consists of marine shoreface deposits, where foreshore, middle and lower shoreface sandstones constitute the primary reservoir. The results of this study of the diagenetic impact on the mineralogical composition, porosity and permeability are presented here. Microcrystalline quartz has preserved porosity in the sandstone, whereas illite, quartz overgrowth and carbonate cement have reduced both porosity and permeability
Base-metal and REE anomalies in lower Palaeozoic sedimentary rocks of Amundsen Land, central North Greenland: implications for Zn-Pb potential
No full textDuring the 2013 field season, siliciclastic and carbonate rocks of the lower Palaeozoic sedimentary succession of the Franklinian Basin in Amundsen Land, central North Greenland, were collected for whole-rock geochemical analysis. These data are evaluated here in an attempt to identify possible hydrothermal signatures related to sediment-hosted Zn-Pb mineralisation, similar to that found in correlative strata at the large Citronen Fjord deposit located c. 100 km to the eastnorth-east. In this paper, we use the term Sedex in a broad sense to describe stratiform, sediment-hosted deposits that formed either by syngenetic (exhalative) processes or by subsea-floor replacement coeval with sedimentation (e.g. Emsbo et al. 2016); the term Mississippi Valley-type (MVT) is used for non-stratiform Zn-Pb deposits that formed epigenetically during late diagenesis or tectonism (e.g. Leach et al. 2010)
The Greenland ice sheet – snowline elevations at the end of the melt seasons from 2000 to 2017
No full textThe Greenland ice sheet has experienced an average mass loss of 142 ± 49 Gt/yr from 1992 to 2011 (Shepherd et al. 2012), making it a significant contributor to sea-level rise. Part of the ice- sheet mass loss is the result of increased dynamic response of outlet glaciers (Rignot et al. 2011). The ice discharge from outlet glaciers can be quantified by coincident measurements of ice velocity and ice thickness (Thomas et al. 2000; van den Broeke et al. 2016). As part of the Programme for monitoring of the Greenland Ice Sheet (PROMICE; Ahlstrøm et al. 2008), three airborne surveys were carried out in 2007, 2011 and 2015, with the aim of measuring the changes in Greenland ice-sheet thicknesses. The purpose of the airborne surveys was to collect data to assess the dynamic mass loss of the Greenland ice sheet (Andersen et al. 2015). Here, we present these datasets of observations from ice-penetrating radar and airborne laser scanning, which, in combination, make us able to determine the ice thickness precisely. Surface-elevation changes between surveys are also presented, although we do not provide an in-depth scientific interpretation of these
Circum-Greenland, ice-thickness measurements collected during PROMICE airborne surveys in 2007, 2011 and 2015
No full textThe Greenland ice sheet has experienced an average mass loss of 142 ± 49 Gt/yr from 1992 to 2011 (Shepherd et al. 2012), making it a significant contributor to sea-level rise. Part of the ice- sheet mass loss is the result of increased dynamic response of outlet glaciers (Rignot et al. 2011). The ice discharge from outlet glaciers can be quantified by coincident measurements of ice velocity and ice thickness (Thomas et al. 2000; van den Broeke et al. 2016). As part of the Programme for monitoring of the Greenland Ice Sheet (PROMICE; Ahlstrøm et al. 2008), three airborne surveys were carried out in 2007, 2011 and 2015, with the aim of measuring the changes in Greenland ice-sheet thicknesses. The purpose of the airborne surveys was to collect data to assess the dynamic mass loss of the Greenland ice sheet (Andersen et al. 2015). Here, we present these datasets of observations from ice-penetrating radar and airborne laser scanning, which, in combination, make us able to determine the ice thickness precisely. Surface-elevation changes between surveys are also presented, although we do not provide an in-depth scientific interpretation of these
Examining the rare-earth elements (REE) supply– demand balance for future global wind power scenarios
No full textRare-earth elements (REE) are considered Critical Raw Materials (CRM; EC 2018; US Department of the Interior 2018) and essential in the technological transformation of the energy sector into carbon-free technologies such as wind turbines, electrified transport and LED-lights. The new technologies have led to swiftly expanding markets for REE products, in which China has achieved a monopolistic role in all segments of the REE value chains. Political strategies aimed to establish REE supplies outside China are currently being implemented within the EU and in other Western countries in order to ensure an adequate future REE supply. However, new REE value chains outside China have not yet materialised. The aim of this paper is to assess whether the global REE supply from present and potential mines can keep pace with the REE demand for the expanding offshore wind energy sector (Fig. 1). A successful development of this sector outside China relies on an adequate supply of particularly neodymium (Nd) and to some extent praseodymium (Pr), terbium (Tb) and dysprosium (Dy), used in permanent magnets for windmill generators. In 2015, about 82% of the global Nd-oxide production was used in the permanent magnets production (Adamas 2016). Here we evaluate the future supply and demand situations for Nd, Pr, Tb and Dy in the global wind energy sector in the form of three scenarios, one for 2020 and two for 2030 based on high and low demand. The balance is discussed. Our assessment reflects the challenge caused by limited insight into the REE supply chains inside China, and the figures presented in this paper are therefore only indicative
Analysis of cod otolith microchemistry by continuous line transects using LA-ICP-MS
No full textFish otoliths, also called ear stones or statoliths, are calcified structures functioning as movement and equilibrium indicators in the inner ear of fish (Fig. 1). From hatching to death these structures grow incrementally, with new material accreted daily (Pannella 1971) in successive layers of protein (1–8%, Degens et al. 1969) and calcium carbonate. The accretion rate of otoliths varies with fish growth, and in temperate species it is usually lowest during the winter season (Hüssy et al. 2010). This results in concentric growth resembling the ringed structure in trees (Fig. 1D), enabling the use of dendrochronological techniques to approximate the age and growth history of fish. During growth, certain elements are incorporated into the otolith structure, some associated with proteins and some with the calcium carbonate component (Thomas et al. 2017), supplying a valuable record of different aspects in fish life history and serving as a potential environmental record. Previous studies show that trace element and isotopic compositions of otoliths can be used as a proxy for reconstructing water chemistry, temperature and salinity (Patterson et al. 1993; Thorrold & Shuttleworth 2000). Other studies demonstrate that elemental histories can be used to investigate fish spawning and migration patterns (e.g. Sturrock et al. 2012), and more recent studies use elements such as Zn, Cu and Mg as indicators of seasonality (Hüssy et al. 2016; Limburg et al. 2018). Combining this knowledge of elemental variation with the micro-beam capabilities of laser ablation inductively coupled plasma mass spectrometry (LAICPMS) turns otolith microchemistry into a powerful tool for studying important parameters fundamental for establishing modern, sustainable fisheries management policies (e.g. stock identification, migration, pollution indicators, spawning habitats, duration of larval and juvenile stages, and magnitude and timing of spawning). We present an analytical method developed by the Geological Survey of Denmark and Greenland (GEUS) in collaboration with the National Institute of Aquatic Resources, Technical University of Denmark (DTU Aqua), for element abundance analysis in otoliths. Analyses of otoliths from Baltic Cod (Gadus morhua; Fig. 1) are used as an example for its application
Towards a common geological data infrastructure for Europe
No full textGeology does not respect national borders. Hence, in order to get geological overviews of Europe, input from geological surveys in more than 35 countries is required. European policy makers have several times been forced to rely on the US Geological Survey to provide e.g. resource estimates from the European continent, but for obvious reasons there is a wish to base European decision making on European knowledge. Consequently, the European Commission and the European Parliament have formulated a request for the establishment of a ‘Geological Service for Europe’. In its strategy towards 2020, EuroGeoSurveys (EGS) addresses the creation of such a service through three pillars. EGS is an umbrella organisation through which national geological survey organisations of 36 European countries cooperate, referred to below as national surveys. The three pillars are designed to integrate input from all national surveys into a system that can swiftly act on urgent needs for knowledge-based decision support. The three pillars relate to joint research, data integration and sharing of facilities (Fig. 1). Whilst the third pillar has only recently been dealt with, the two first have already advanced through a number of recent initiatives. Having been a key player in numerous EU projects for many years, the Geological Survey of Denmark and Greenland (GEUS) has attained a central role in the implementation of these two pillars of the strategy, both as coordinator of the European Geological Data Infrastructure (EGDI, www.europe-geology.eu) and as one of the biggest players in the so-called GeoERA programme. GEUS participates in ten projects and is a partner in the secretariat and the coordinator of the GeoERA Information Platform. The present paper outlines the main steps towards the current situation and provides a background for GEUS’ role in this
Sedimentology, geochemistry and reservoir properties of Upper Jurassic deep marine sediments (Hareelv Formation) in the Blokelv-1 borehole, Jameson Land Basin, East Greenland
No full textThe fully cored Blokelv-1 borehole was drilled through Upper Jurassic strata in the central part of the Jameson Land Basin, central East Greenland. The borehole reached a total depth of 233.8 m with nearly 100% recovery of high-quality core. An extensive analytical programme was undertaken on the core; sedimentological interpretation and reservoir characterisation were based on facies analysis combined with conventional core analysis, bulk geochemistry and spectral gamma and density scanning of the core. The Upper Jurassic Hareelv Formation was deposited in relatively deep water in a slope-to-basin setting where background sedimentation was dominated by suspension settling of organic-rich mud in oxygen-depleted conditions. Low- and high-density gravity-flow sandstone interbeds occur throughout the cored succession. About two-thirds of the high-density turbidite sandstones were remobilised and injected into the surrounding mud-rock. The resulting succession comprises nearly equal amounts of mudstones and sandstones in geometrically complex bodies. Ankerite cementation occurs in 37% of the analysed sandstones in varying amounts from minor to pervasive. Such ankerite-cemented sandstones can be identified by their bulk geochemistry where Ca > 2 wt%, Mg > 1 wt% and C > 1 wt%. The analysed mudstones are rich in Al, Fe, Ti and P and poor in Ca, Mg, Na and Mn. The trace-metal content shows a general increase in the upper part of the core reflecting progressive oxygen depletion at the sea floor. The reservoir properties of the Blokelv-1 sandstones were evaluated by both conventional core analysis and using log-derived porosity and permeability curves. The high-density turbidite beds and injectite bodies are a few centimetres to several metres thick and show large variations in porosity and permeability, in the range of 6–26 % for porosity and 0.05–400 mD for permeability. Individual sandstone units that are 1–7 m thick yield a net vertical reservoir thickness of 40 m with porosities of 15–26% and permeabilities of 1–200 mD. Heterolithic sandstone–mudstone units are generally characterised by poor reservoir quality with porosities of 2–14% and permeabilities of 0.1–0.6 mD
Update of the seamless 1:500 000 scale geological map of Greenland based on recent field work in the Wandel Sea Basin, eastern North Greenland
No full textGeological maps are core products of national geological surveys and represent the sum of geological knowledge of any given area. However, dedicated and extensive mapping projects in the Arctic are mostly a thing of the past due to difficulty in financing such costly basic research efforts. Today, an overview of the geology of Greenland is portrayed by a seamless digital 1:500 000 scale geological map (Kokfelt et al. 2013; Pedersen et al. 2013), based on printed maps on this scale produced since 1982 by the Geological Survey of Denmark and Greenland (GEUS; see Holst et al. 2013). The digital map now makes it possible to update smaller areas with new, published or otherwise quality-controlled geological data (e.g. Kolb et al. 2016). This ensures that the map reflects the current state of geological knowledge without undertaking extensive new mapping to update individual map sheets, as has previously been the modus operandi. An online version of the map is available from www.greenmin.dk/map. However, procedures are required to ensure that updates are carried out routinely and that the quality and coherence of the updated map is of the Survey’s standards. Results of recent field work in the Wandel Sea Basin (Fig. 1) and in particular the publication of a new geological map sheet Kilen on a scale of 1:100 000 (Svennevig in press) have implications for the geology shown on the above mentioned 1:500 000 scale seamless geological map of Greenland. The post-Devonian part of this map in eastern North Greenland has been updated according to the results of studies published since the publication of the original printed maps (Bengaard & Henriksen 1986; Jepsen 2000). The changes do not call for an update of the 1:2 500 000 scale geological map of Greenland (Henriksen et al. 2009)
New subsurface mapping offshore southern West Greenland using geophysical and geological data
No full textThe West Greenland continental margin has been the subject of petroleum exploration by companies and research projects since the 1970s and many data have been acquired since. Licensing rounds issued by the Greenland authorities in 2002 and 2004 offshore southern West Greenland resulted in company licenses which led to data acquisition and three exploration wells. The extensive new data form a basis for updated mapping by means of data, new analyses of the subsurface geology and improved understanding of the stratigraphy and the geological development. The Geological Survey of Denmark and Greenland (GEUS) has recently completed a comprehensive mapping project of the subsurface in an area covering 116 000 km2 offshore southern West Greenland (Fig. 1). The results include maps displaying large structural highs and faults, Cretaceous sedimentary basins and volcanic areas, illustrated by cross-sections through the area. A new seismic stratigraphy with eight mega-units from the seabed to the basement was also defined. In addition, studies from wells of biostratigraphy and petrology were carried out that provide important new information. The new data include extensive 2D seismic data and eight wells including the three exploration wells AT2-1, AT7-1 and LF7-1 drilled in 2011 by Cairn Energy (Fig. 1). Key results of the work are summarised below