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.

Access to geological structures, density, minerals and textures through novel combination of 3D tomography, XRF and sample weight

Abstract: Scanning drill cores using combined data from X-Ray Transmission and X-Ray Fluorescence, automatically measuring the weight, and performing 3D tomography of the core at the same time, gives a high-...

High resolution seismic imaging at the planned tunnel entrance to the Forsmark repository for spent nuclear fuel, central Sweden

Abstract: The Swedish Nuclear Waste Management Company (SKB) plans to build a repository for storage of high-level radioactive spent nuclear fuel at the Forsmark site in central Sweden at a depth of about 470 m. The planned repository will cover an area of about 3.6 km2 at this depth. Prior to beginning excavation and tunneling, some detailed geophysical surveys are being performed at the planned site. One of these was a refraction seismic survey to determine depth to bedrock in the vicinity of the planned access ramp. Two lines, each about 300 m long and spaced about 35 m apart, were acquired in August 2011. Since the bedrock topography is known to be highly variable, a close receiver (2 m) and source (6 m) spacing was required to map it. This close spacing allowed the data also to be treated as reflection seismic data and some adjustments to the acquisition procedure were made in the field with this in mind to aid in the later processing. The main adjustment was that seismic data were recorded on all geophone stations simultaneously. That is, as shots were fired along one line, data were recorded along both that line and the other one. Likewise, when shots were fired along the other line, data were recorded along that line and the first line. This adjustment allowed semi-3D coverage between the lines. Results from first break traveltime tomography along the lines indicate a depth to bedrock that is greater than that found from geotechnical observations along the lines. This discrepancy is attributed to the uppermost bedrock being highly fractured and having a velocity significantly below that expected from the intact bedrock deeper down. Reflection seismic processing of the data shows a reflection at about 20 ms (about 60 m). The reflection is interpreted to have a gentle northwesterly dip component to it. Comparison with core data in the area suggests that the reflection is from a thin (a few metres thick) fracture zone, although none of the boreholes actually penetrate the reflector where it is mapped by the seismic data. This fracture zone may be part of a larger fracture zone mapped by core drilling further to the east. The newly mapped reflector may be crossed by the ramp when excavation begins. Further seismic surveying towards the west is required to verify if this will be the case.

Studies of the Variations in Water Content in the Unsaturated Zone of an Esker

Abstract: In this study the changes in water content in the unsaturated zone of a large esker at Tarnsjo have been measured with a combined gamma/neutron probe. Periods of heavy rainfall and intense snow-melting have resulted in infiltration events, which later have been traced as zones with high water content moving downwards in the unsaturated zone towards the groundwater table. The results indicate a velocity of the movement of such zones of about 1.5-3.0 m/month. These results are compared with those obtained by Andersen and Sevel (1974) from a study in Denmark, and with preliminary results from a study of the movement of tritiated water in the unsaturated zone of the Tarnsjo esker performed by Z. Dressie.