The Ramså Basin on Andøya, Northern Norway is the only known Mesozoic basin onshore Norway. The primary basement rocks in the area are granodiorite. The Mesozoic sedimentary strata of the Ramså basin comprise sandstones and different clay stones of Cretaceous and Jurassic ages. Resistivity of the subsurface can be investigated by electric and electromagnetic (EM) geophysical methods to delineate the extension of the Ramså basin. Borehole logging, electrical resistivity tomography (ERT) and helicopter-borne frequency-domain EM (HEM) surveys were performed in the area in the frame of different projects to gain a better understanding of the basin geology and structural settings.

A quasi-3D inversion of HEM data shows a good agreement with borehole resistivity and ERT resistivity. HEM interpretation presents a 3D subsurface resistivity image of a larger area in comparison to what could have been drawn from few ERT lines and borehole logging. HEM interpretation together with other ERT and borehole resistivity indicates extension of Ramså basin boundary beyond presently mapped boundary. Two new highly conductive areas are identified by HEM data interpretation and one of the areas is confirmed with presence of graphite and sulfide minerals by geological observations.


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  1. AarhusInv
    AarhusInv [2015] Manual for inversion program, ver. 6.3. HydroGeophysics Group (HGG), University of Aarhus, Denmark.
    [Google Scholar]
  2. Brönner, M., Dalsegg, E., Fabian, K., Rønning, J.S. and Tønnesen, J.F.
    [2012] Geophysical methods. In: Olesen, O., Bering, D., Brönner, M., Dalsegg, E., Fabian, K., Fredin, O., Gellein, J., Husteli, B., Magnus, C., Rønning, J.S., Solbakk, T., Tønnesen, J.F. and Øverland, J.A. (Eds.): Tropical Weathering In Norway, TWIN Final Report, NGU Report, 2012.005, 19–26.
    [Google Scholar]
  3. Dalland, A.
    [1975] The Mesozoic rocks of Andøy, northern Norway. Norges geologiske undersøkelse316, 271–287.
    [Google Scholar]
  4. Elvebakk, H., Brönner, M., Gellein, J. and Rønning, J.S.
    [2016] Geofysisk logging av 4 borehull i Ramså feltet, Andøya. NGU report, 2016.023 (Confidential).
    [Google Scholar]
  5. Friis, J.P.
    [1903] Andøens kulfelt. Norges Geologiske Undersøkelse36 (1).
    [Google Scholar]
  6. Geotech
    [1997] Hummingbird Electromagnetic System: User’s manual. Geotech Ltd., Canada.
    [Google Scholar]
  7. Henningsen, T. and Tveten, E.
    [1998] Berggrunnskart of Andøya M 1: 250 000. NGU, Norway
    [Google Scholar]
  8. Rodionov, A., Ofstad, F. and Tassis, G.
    [2012] Helicopter-borne magnetic, electromagnetic and radiometric geophysical survey at Andøya, Nordland County. NGU Report, 2012.056.
    [Google Scholar]

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