3-D magnetotelluric inversion and model validation with gravity data for the investigation of flood basalts and associated volcanic rifted margins |
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| Authors: | S Hautot R T Single J Watson N Harrop D A Jerram P Tarits K Whaler G Dawes |
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| Institution: | IUEM-UBO, UMR CNRS 6538 'Domaines Océaniques', Place Nicolas Copernic, 29280;Plouzané, France Statoil A.S.A., Heidrun Petek, PO Box 273, N-7501;Stjørdal, Norway ARK Geophysics, Featherstone Road, Wolverton Mill, Milton Keynes MK12 5EU,;UK University of Durham, Department of Earth Sciences, Science Laboratories, South Road, Durham DH1 3LE,;UK School of GeoSciences, Grant Institute, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JW,;UK |
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| Abstract: | 20 magnetotelluric (MT) soundings were collected on the Isle of Skye, Scotland to provide a high-resolution three-dimensional (3-D) electrical resistivity model of a volcanic province within the framework of a project jointly interpreting gravity, seismic, geological and MT data. The full 3-D inversion of the MT data jointly interpreted with gravity data reveals upper crustal structure. The main features of the model are interpreted in conjunction with previous geological mapping and borehole data. Our model extends to 13 km depth, several kilometres below the top of the Lewisian basement. The top of the Lewisian basement is at approximately 7–8 km depth and the topography of its surface was controlled by Precambrian rifting, during which a 4.5 km thick sequence of Torridonian sediments was deposited. The Mesozoic sediments above, which can reach up to 2.2 km thick, have small-scale depocentres and are covered by up to 600 m of Tertiary lava flows. The interpretation of the resistivity model shows that 3-D MT inversion is an appropriate tool to image sedimentary structures beneath extrusive basalt units, where conventional seismic reflection methods may fail. |
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| Keywords: | 3-D inversion gravity magnetotellurics rifted margin |
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