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Tectonics

Electrical resistivity in the crust and mantle are a function of porosity and water content in the upper crust and temperature, melt fraction and chemical composition (i.e. hydration) in the mantle.

We use seafloor Magnetotellurics, a natural source electromagnetic method with a depth of penetration down to several hundred kilometers into the Earth, in order to image large scale tectonic features such as hot-spots, volcanic rifting or subduction zones. 

Hotspot Example 3-D electrical conductivity model of the Tristan da Cunha Hotspot. (a) to (f) show horizontal slices at different depths. (g) to (l) show vertical sections along lines A-A′ to F-F′. Colors indicate resistivity values (inverse of conductivity) in log scale. Crosses denote sites used for 3-D inversion analysis, gray contour lines outline bathymetry.White dashed lines represent the depths or profiles of the horizontal slices or the vertical sections. Baba et al., 2016.
Subduction Zone Example 2D electrical resistivity model imaging the hydration and dehydration cycle of the Costa Rican subduction zone(top) and a schematic interpretation (bottom). Worzewski et al., 2010.

Projects

  Archimedes

  SPP 1375 Sample

  Alboran Sea

  SFB574

Cruises

SO267

MSM17-1

MSM17-2

MSM24

Publications

Baba, K., Chen, J., Sommer, M., Utada, H., Geissler, W. H., Jokat, W. and Jegen, M (2017) Marine magnetotellurics imaged no distinct plume beneath the Tristan da Cunha hotspot in the southern Atlantic Ocean. Open Access Tectonophysics, 716 . pp. 52-63. DOI 10.1016/j.tecto.2016.09.033

Bonadio, R., Geissler, W. H., Lebedev, S., Fullea, J., Ravenna, M., Celli, N. L., Jokat, W., Jegen, M. , Sens-Schönfelder, C. and Baba, K. (2018) Hot Upper Mantle Beneath the Tristan da Cunha Hotspot From Probabilistic Rayleigh-Wave Inversion and Petrological Modeling. Open Access Geochemistry, Geophysics, Geosystems, 19 . pp. 1412-1428. DOI 10.1002/2017GC007347

Garcia, X., Seillé, H., Elsenbeck, J., Evans, R. L., Jegen, M. , Hölz, S., Ledo, J., Lovatini, A., Marti, A., Marcuello, A., Queralt, P., Ranero, C. R. and Ungarelli, C. (2015) Structure of the mantle beneath the Alboran basin from magnetotelluric soundings. Open Access Geochemistry, Geophysics, Geosystems, 16 . pp. 4261-4274. DOI 10.1002/2015GC006100

Avdeeva, A., Avdeev, D. and Jegen, M. (2012) Detecting a salt dome overhang with magnetotellurics: 3D inversion methodology and synthetic model studies. Open Access Geophysics, 77 (4). E251-E263. DOI 10.1190/geo2011-0167.1

Brasse, H., Kapinos, G., Mütschard, L., Alvarado, G. E., Worzewski, T. and Jegen-Kulcsar, M. (2009) Deep electrical resistivity structure of northwestern Costa Rica . Open Access Geophysical Research Letters, 36 . L02310. DOI 10.1029/2008GL036397

Avdeeva, A., Moorkamp, M., Avdeev, D., Jegen, M. and Miensopust, M. (2015) Three-dimensional inversion of magnetotelluric impedance tensor data and full distortion matrix. Open Access Geophysical Journal International, 202 (1). pp. 464-481. DOI 10.1093/gji/ggv144

Geissler, W. H., Jokat, W., Jegen, M. and Baba, K. (2017) Thickness of the oceanic crust, the lithosphere, and the mantle transition zone in the vicinity of the Tristan da Cunha hot spot estimated from ocean-bottom and ocean-island seismometer receiver functions. Open Access Tectonophysics, 716 . pp. 33-51. DOI 10.1016/j.tecto.2016.12.013 .

Geissler, W. H., Wintersteller, P., Maia, M., Strack, A., Kammann, J., Eagles, G., Jegen, M., Schloemer, A. and Jokat, W. (2020) Seafloor evidence for pre-shield volcanism above the Tristan da Cunha mantle plume. Open Access Nature Communications, 11 (Art.Nr. 4543). DOI 10.1038/s41467-020-18361-4

Jegen, M., Avdeeva, A., Berndt, C. , Franz, G., Heincke, B., Hölz, S., Neska, A., Marti, A., Planert, L., Chen, J., Kopp, H., Baba, K., Ritter, O., Weckmann, U., Meqbel, N. and Behrmann, J. (2016) 3-D Magnetotelluric Image of Offshore Magmatism at the Walvis Ridge and Rift Basin. Open Access Tectonophysics, 683 . pp. 98-108. DOI 10.1016/j.tecto.2016.06.016

Jegen, M. , and Edwards, R. N. (1998) The Electrical Properties of a 2D Conductive Zone underneath the Juan de Fuca Ridge. Open Access Geophysical Research Letters, 25 (19). pp. 3647-3650. DOI 10.1029/98GL52807

Kapinos, G., Weckmann, U., Jegen-Kulcsar, M., Meqbel, N., Neska, A., Katjiuongua, T. T., Hölz, S. and Ritter, O. (2016) Electrical resistivity image of the South Atlantic continental margin derived from onshore and offshore magnetotelluric data. Open Access Geophysical Research Letters, 43 (1). pp. 154-160. DOI 10.1002/2015GL066811

Neska, A., Nowozynski, K., Reda, J. and Jegen-Kulcsar, M. D.  (2013) Reducing motion noise in marine magnetotelluric measurements by means of tilt records. Open Access Geophysical Journal International, 194 (1). pp. 304-315. DOI 10.1093/gji/ggt087

Schlömer, A., Geissler, W. H., Jokat, W. and Jegen, M. (2017) Seismicity in the vicinity of the Tristan da Cunha hotspot: Particular plate tectonics and mantle plume presence. Open Access Journal of Geophysical Research: Solid Earth, 122 (12). pp. 10427-10439. DOI 10.1002/2017JB015017

Schlömer, A., Geissler, W. H., Jokat, W. and Jegen, M. (2017) Hunting for the Tristan Mantle Plume - An upper mantle tomography around the volcanic island of Tristan da Cunha. Earth and Planetary Science Letters, 462 . pp. 122-131. DOI 10.1016/j.epsl.2016.12.028.

Worzewski, T., Jegen, M., Kopp, H., Brasse, H. and Taylor, W. T. (2011) Magnetotelluric image of the fluid cycle in the Costa Rican subduction zone. Nature Geoscience, 4 . pp. 108-111. DOI 10.1038/ngeo1041

Worzewski, T., Jegen, M. and Swidinsky, A. (2012) Approximations for the 2-D coast effect on marine magnetotelluric data. Open Access Geophysical Journal International, 189 . pp. 357-368. DOI 10.1111/j.1365-246X.2012.05385.x

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Dynamics of the Ocean Floor

Marine EM

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