MT and reflection seismics in northwestern Skellefte Ore District, Sweden

Maria de los Angeles Garcia Juanatey*, Ari Tryggvason, Christopher Juhlin, Ulf Bergstrom, Juliane Hubert, Laust B. Pedersen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A seismic reflection and MT survey was carried out along a 27-km long transect in northwestern Skellefte District, as part of a bigger 3D modeling project. The main motivation for the data acquisition is to elucidate the geologic relationship between the known mineralizations in the Adak mining camp to the north and in the well studied Kristineberg area south of the transect. The seismic reflection data were acquired with a VIBSIST system, and show reflectivity down to 3 s. Apart from the conventional processing for crystalline environments, the seismic data was also subject to an azimuthal binning procedure and cross-dip analysis, allowing the orientation of planar reflectors in 3D. Regarding the MT data, it is primarily of good quality along the 17 installed sites. The inversion of the determinant of the im-pedance tensor yielded a stable 2D resistivity model, dominated by resistors corresponding to the postorogenic intrusions along the transect. Adding the location of the analyzed seismic reflectors in the MT inversion rendered an integrated model that facilitated a preliminary joint interpretation of the data sets. Overall, the results are in good agreement with surface observations and reveal a crude configuration of the geologic units below the transect. The most prominent outcomes are the lateral and depth extent of the large postorogenic intrusions in the area reaching to 5- or 6-km depth, the dimensions of the nearly vertical Brannas gabbro extending to 6-km depth, and the presence of enhanced conductivities along the transect at about 10 km depth. The latter is probably related to the deep conductor previously identified in the district.

Original languageEnglish
Pages (from-to)B65-B76
Number of pages12
JournalGeophysics
Volume78
Issue number2
DOIs
Publication statusPublished - 2013

Keywords

  • KRISTINEBERG MINING AREA
  • NORTHERN SWEDEN
  • MAGNETOTELLURIC DATA
  • WESTERN PART
  • FENNOSCANDIAN SHIELD
  • IMPEDANCE TENSOR
  • SOUTHERN SWEDEN
  • VOLCANIC ARC
  • INVERSION
  • DEPOSITS

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