Magnetotelluric investigation of the lower crust and upper mantle beneath Iceland
Article Sidebar
Published:
Dec 22, 1978
Keywords:
Magnetotellurics,
Iceland,
Electrical structure,
Low resistivity layer,
Temperature gradient,
Partial melting
Volumes
Vols. 1-18 (1924-1944), ISSN 0044-2801
Main Article Content
Abstract
Magnetotelluric measurements were made at 12 sites on a 210 km long profile in northern and eastern Iceland. The profile crosses areas of different geological age ranging from Tertiary flood basalt to the presently active zone of rifting and volcanism. Beneath the investigated area, at a depth of a few km down to about 20 km there exists a 5 km thick layer with low resistivity amounting to 15 Ωm which is imbedded between layers of higher resistivities. The depth to the low resistivity layer increases with increasing distance from the spreading axis. The low resistivity layer is presumably caused by partial melting at the base of the crust and at the top of the anomalous mantle beneath Iceland. Comparison with laboratory measurements confirms a basaltic composition and a temperature of 1,000-1,100° C of the good conductor, and probably partially molten peridotite in the upper mantle beneath. Mean temperature gradients in the crust calculated from the magnetotelluric data are in good agreement to surface temperature gradients measured in drill holes.
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Article Details
How to Cite
Beblo, M., & Bjornsson, A. (1978). Magnetotelluric investigation of the lower crust and upper mantle beneath Iceland. Journal of Geophysics, 45(1), 1-16. Retrieved from https://journal.geophysicsjournal.com/JofG/article/view/168
Section
References
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Beblo, M. (1972) A transportable battery-operated electrograph for permanent recording of the induced electric field of the earth. J. Geophys. 38:133-143
Beblo, M. (1974) Die elektrische Leitfahigkeit unter den Ostalpen, abgeleitet aus magnetotellurischen Messungen langs eines Profiles vom Alpennordrand bis zu den Hohen Tauern. Diss. Fak. Geowiss. Univ. Munich
Berdichevsky, M.N., Dimitriev, V.J. (1976) Basic principles of interpreation of magnetotelluric sounding curves. In: Adam, A. (Ed.) Geoelectric and geothermal studies, pp. 165-221. Budapest: Akademiai Kiado
Berktold, A., Beblo, M., Kemmerle, K. (1976) On the distribution of the electrical conductivity below the Eastern Alps. Geol. Rundschau 65:715-732
Bjornsson, A. (1976) Electrical resistivity of layer 3 in the Icelandic crust. In: Greinar V. pp. 7-23, Reykjavik: Societas Scientiarum Islandica
Bjornsson, A., Saemundsson, K., Einarsson, P., Tryggvason, E., Granvold, K. (1977) Current rifting episode in north Iceland. Nature 266:318-323
Bondarenko, A.T., Galdin, N.Y. (1972) On the physicomechanical and electrical properties of basalts at high pressures and temperatures. Izv. Earth Phys. 5:28-40
Garland, G.D., Ward, J. (1965) Magnetic variation measurements in Iceland. Nature 205:269-270
Haak, V. (1978) Interpretations-Verfahren fur die Magnetotellurik unter besonderer Berucksichtigung lateral variierender elektrischer Leitfahigkeit im Erdinnern und eines raumlich inhomogenen
induzierenden Magnetfelds. Munich: Bayerische Akademie der Wissenschaften
Hermance, J.F. (1973) An electrical model for the sub-Icelandic crust. Geophysics 38:3-13
Hermance, J.F., Garland, G.D. (1968a) Deep electrical structure under Iceland. J. Geophys. Res. 73:3797-3800
Hermance, J.F., Garland, G.D. (1968b) Magnetotelluric deepsounding experiments in Iceland. Earth Planet. Sci. Lett. 4:469-474
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Hermance, J.F., Grillot, L.R. (1974) Constraints on temperatures beneath Iceland from magnetotelluric data. Phys. Earth Planet. Inter. 8:1-12
Hermance, J.F., Nur, A., Bjornsson, S. (1972) Electrical properties of basalt: relation of laboratory to in situ measurements. J. Geophys. Res. 77:1424-1429
Hermance, J.F., Thayer, R.E., Bjornsson, A. (1975) The telluric-magnetotelluric method in the regional assessment of geothermal potential. In: Proceedings, Second United Nations Symp. on the development and use of geothermal resources, San Francisco, pp. 1037-1048. Berkeley-San Francisco: Lawrence Berkeley Lab., Univ. of California
Kiessling, W. (1970) Untersuchung der Variationen des erdelektrischen und erdmagnetischen Feldes im Oberpfalzer Wald zur Bestimmung der elektrischen Leitfahigkeit in grol3eren Tiefen mit der Methode der Magnetotellurik. Dipl.-Arbeit, Inst. Angew. Geophys. Univ. Munich
Kitharov, N.I., Slutskiy, A.B., Pugin, A.V. (1970) Electrical conductivity of basalts at high T-P and phase transitions under upper mantle conditions. Phys. Earth Planet. Inter. 3:334-342
Palmason, G. (1971) Crustal structure of Iceland from explosion seismology. Rit XL, Reykjavik: Societas Scientiarum Islandica. pp. 187
Palmason, G. (1973) Kinematics and heat flow in a volcanic rift zone with application to Iceland. Geophys. J. 33:451-481
Palmason. G., Saemundsson, K. (1974) Iceland in the relation to the Mid-Atlantic Ridge. Ann. Rev. Earth Planet. Sci. 2:25-50
Parkhomenko, E.I. (1967) Electrical properties of rocks. Plenum, New York
Presnall, D.C., Simmons, C.L., Porath, H. (1972) Changes in electrical conductivity of a synthetic basalt during melting. J. Geophys. Res. 77:5665-5672
Saemundsson, K. (1974) Evolution of the axial rifting zone in northern Iceland and the Tjornes fracture zone. Hull. Geol. Soc. Am. 85:495-504
Schmucker, U. (1974) Erdmagnetische Tiefensondierung mit langperiodischen Variationen. In: Tiefensond, A. Berktold (Ed.) Protokoll DFG-Kolloquium Erdmagn, pp. 313-342, Grafrath-Munich
Shankland, T.J., Waff, H.S. (1977) Partial melting and electrical conductivity anomalies in the upper mantle. J. Geophys. Res. 82:5409-5417
Thayer, R.E. (1975) Telluric-magnetotelluric investigations of regional geothermal processes in Iceland. Ph.D. thesis, Providence: Dept. Geological Sciences, Brown University
Waff, S.H. (1974) Theoretical considerations of electrical conductivity in a partially molten mantle and implications for geothermometry. J. Geophys. Res. 79:4003-4010
Zverev, S.M., Boldyrev, S.A., Bourmin, V. Yu, Mironova, V.I. (1978) Weak earthquakes in the northern part of the rift zone of Iceland. J. Geophys. 44:283-296
Beblo, M. (1972) A transportable battery-operated electrograph for permanent recording of the induced electric field of the earth. J. Geophys. 38:133-143
Beblo, M. (1974) Die elektrische Leitfahigkeit unter den Ostalpen, abgeleitet aus magnetotellurischen Messungen langs eines Profiles vom Alpennordrand bis zu den Hohen Tauern. Diss. Fak. Geowiss. Univ. Munich
Berdichevsky, M.N., Dimitriev, V.J. (1976) Basic principles of interpreation of magnetotelluric sounding curves. In: Adam, A. (Ed.) Geoelectric and geothermal studies, pp. 165-221. Budapest: Akademiai Kiado
Berktold, A., Beblo, M., Kemmerle, K. (1976) On the distribution of the electrical conductivity below the Eastern Alps. Geol. Rundschau 65:715-732
Bjornsson, A. (1976) Electrical resistivity of layer 3 in the Icelandic crust. In: Greinar V. pp. 7-23, Reykjavik: Societas Scientiarum Islandica
Bjornsson, A., Saemundsson, K., Einarsson, P., Tryggvason, E., Granvold, K. (1977) Current rifting episode in north Iceland. Nature 266:318-323
Bondarenko, A.T., Galdin, N.Y. (1972) On the physicomechanical and electrical properties of basalts at high pressures and temperatures. Izv. Earth Phys. 5:28-40
Garland, G.D., Ward, J. (1965) Magnetic variation measurements in Iceland. Nature 205:269-270
Haak, V. (1978) Interpretations-Verfahren fur die Magnetotellurik unter besonderer Berucksichtigung lateral variierender elektrischer Leitfahigkeit im Erdinnern und eines raumlich inhomogenen
induzierenden Magnetfelds. Munich: Bayerische Akademie der Wissenschaften
Hermance, J.F. (1973) An electrical model for the sub-Icelandic crust. Geophysics 38:3-13
Hermance, J.F., Garland, G.D. (1968a) Deep electrical structure under Iceland. J. Geophys. Res. 73:3797-3800
Hermance, J.F., Garland, G.D. (1968b) Magnetotelluric deepsounding experiments in Iceland. Earth Planet. Sci. Lett. 4:469-474
Hermance, J.F., Grillot, L.R. (1970) Correlation of magnetotelluric, seismic and temperature data from southwest Iceland. J. Geophys. Res. 75:6582-6591
Hermance, J.F., Grillot, L.R. (1974) Constraints on temperatures beneath Iceland from magnetotelluric data. Phys. Earth Planet. Inter. 8:1-12
Hermance, J.F., Nur, A., Bjornsson, S. (1972) Electrical properties of basalt: relation of laboratory to in situ measurements. J. Geophys. Res. 77:1424-1429
Hermance, J.F., Thayer, R.E., Bjornsson, A. (1975) The telluric-magnetotelluric method in the regional assessment of geothermal potential. In: Proceedings, Second United Nations Symp. on the development and use of geothermal resources, San Francisco, pp. 1037-1048. Berkeley-San Francisco: Lawrence Berkeley Lab., Univ. of California
Kiessling, W. (1970) Untersuchung der Variationen des erdelektrischen und erdmagnetischen Feldes im Oberpfalzer Wald zur Bestimmung der elektrischen Leitfahigkeit in grol3eren Tiefen mit der Methode der Magnetotellurik. Dipl.-Arbeit, Inst. Angew. Geophys. Univ. Munich
Kitharov, N.I., Slutskiy, A.B., Pugin, A.V. (1970) Electrical conductivity of basalts at high T-P and phase transitions under upper mantle conditions. Phys. Earth Planet. Inter. 3:334-342
Palmason, G. (1971) Crustal structure of Iceland from explosion seismology. Rit XL, Reykjavik: Societas Scientiarum Islandica. pp. 187
Palmason, G. (1973) Kinematics and heat flow in a volcanic rift zone with application to Iceland. Geophys. J. 33:451-481
Palmason. G., Saemundsson, K. (1974) Iceland in the relation to the Mid-Atlantic Ridge. Ann. Rev. Earth Planet. Sci. 2:25-50
Parkhomenko, E.I. (1967) Electrical properties of rocks. Plenum, New York
Presnall, D.C., Simmons, C.L., Porath, H. (1972) Changes in electrical conductivity of a synthetic basalt during melting. J. Geophys. Res. 77:5665-5672
Saemundsson, K. (1974) Evolution of the axial rifting zone in northern Iceland and the Tjornes fracture zone. Hull. Geol. Soc. Am. 85:495-504
Schmucker, U. (1974) Erdmagnetische Tiefensondierung mit langperiodischen Variationen. In: Tiefensond, A. Berktold (Ed.) Protokoll DFG-Kolloquium Erdmagn, pp. 313-342, Grafrath-Munich
Shankland, T.J., Waff, H.S. (1977) Partial melting and electrical conductivity anomalies in the upper mantle. J. Geophys. Res. 82:5409-5417
Thayer, R.E. (1975) Telluric-magnetotelluric investigations of regional geothermal processes in Iceland. Ph.D. thesis, Providence: Dept. Geological Sciences, Brown University
Waff, S.H. (1974) Theoretical considerations of electrical conductivity in a partially molten mantle and implications for geothermometry. J. Geophys. Res. 79:4003-4010
Zverev, S.M., Boldyrev, S.A., Bourmin, V. Yu, Mironova, V.I. (1978) Weak earthquakes in the northern part of the rift zone of Iceland. J. Geophys. 44:283-296