Geological Survey of Sweden

About: Geological Survey of Sweden is a government organization based out in Uppsala, Sweden. It is known for research contribution in the topics: Metamorphism & Zircon. The organization has 316 authors who have published 671 publications receiving 18333 citations. The organization is also known as: Sveriges Geologiska Undersökning.

A model for the formation of the iron, manganese and sulphide ores of central Sweden

Abstract: The non-apatitic iron ores, manganese ores and sulphide ores of central Sweden, which occur in a volcano-sedimentary complex of Early Proterozoic age, have a common volcanogenic origin. The close association between specific ore types and metavolcanics suggests a stratigraphic control of the ores on a regional scale. Deposited in basins, the ores formed with increasing water depth (increasing pH and decreasing Eh) in the following order: quartz-banded iron ores mostly lacking sulphides; non-man-ganiferous skarn iron ores with Cu-Fe sulphides; manganiferous skarn iron ores with Zn-Pb sulphides, and Fe2+-Mn2+ silicates (eulysites). The latter two ore types occur adjacent to argillites/greywackes indicating a reducing environment. The manganese oxide ores of the Langban type represent a formation intermediate between the quartzbanded iron ores and the manganiferous skarn iron ores.

Stratigraphy and geothermal assessment of Mesozoic sandstone reservoirs in the Öresund Basin - exemplified by well data and seismic profiles

Abstract: The Oresund Basin in the transnational area between Sweden and Denmark forms a marginal part of the Danish Basin. The structural outline and stratigraphy of the Mesozoic succession is described, and a novel interpretation and description of the subsurface geology and geothermal potential in the North Sjaelland Half-graben is presented. The subsurface bedrock in the basin includes several Mesozoic intervals with potential geothermal sandstone reservoirs. Parts of the succession fulfill specific geological requirements about distribution, composition and quality of the sandstones. A characterisation of these is presently of great interest in the attempt to identify geothermal reservoirs suitable for district heating purposes. The results presented in this paper include for the first time a comprehensive description of the stratigraphic intervals as well as the characteristics of the potential Mesozoic geothermal reservoirs in the Oresund region, including their distribution, composition and physical properties. This is illustrated by seismic cross-sections and well sections. In addition, results from analyses and evaluations of porosity, permeability, formation fluids and temperature are presented. Six potential geothermal reservoirs in the Mesozoic succession are described and assessed. Primary focus is placed on the characteristics of the reservoirs in the Lower Triassic and Rhaetian–Lower Jurassic succession. The study shows that the Mesozoic reservoir sandstones vary considerably with respect to porosity and permeability. Values range between 5–25% for the pre-Rhaetian Triassic sandstones, but are commonly > 25% for the Rhaetian–Lower Jurassic and Lower Cretaceous sandstones. The corresponding permeability rarely reaches above 500 mD for the pre-Rhaetian Triassic reservoirs, but often reach >1 Darcy for the Rhaetian–Lower Jurassic and the Lower Cretaceous sandstones. The interpreted formation temperatures for the reservoirs in the Oresund Basin are: 45–50°C at 1500 m, 60–70°C at 2000 m and 70–90°C at 2500 m depth . The combined results provide a geological framework for making site specific predictions regarding appraisal of viable geothermal projects for district heating purposes in the region as well as reducing the risk of unsuccessful wells (Less)

Boat-towed radio-magnetotelluric and controlled source audio-magnetotelluric study to resolve fracture zones at Äspö Hard Rock Laboratory site, Sweden

Abstract: Boat-towed radio-magnetotelluric (RMT) measurements using signals between 14 and 250 kHz have attracted increasing attention in the near-surface applications for shallow water and archipelago areas ...

Impacts from Deposition on Swedish Forest Ecosystems Identified by Integrated Monitoring

Abstract: Integrated monitoring of ecosystems (IM) is an international co-operative programme (ICP) to control effects of air pollution and climate change on water, soil and biological systems. It is a part of the Convention on Long-Range Transboundary Air Pollution (CLRTAP) of the United Nations Economic Commission of Europe (UN/ECE). The ICP-IM is undertaken on sites/catchments to investigate acidification, eutrophication and heavy metals with an integrated approach. In Sweden, long-term time series from forest ecosystems, with a long and stable continuity, will reveal trends and changes in processes and enable modelling to be undertaken. Investigations of acidity/alkalinity in relation to mineral and organic acids indicated the importance of atmospheric deposition. Recent results show very high inorganic nitrogen retention (99%), a net loss of sulphur originating mainly from organic horizons, and a high inorganic aluminium content in the illuvial soil horizons which could be detrimental to forests. Forest deficiency could also be caused by an observed ongoing translocation of Zn to deeper soil layers implying a movement towards increased release to surface waters.