An anomaly of the upper mantle below the Rhine Graben, studied by the inductive response of natural electromagnetic fields

Abstract

The methods of Magnetotellurics (MT) and Geomagnetic Deep Sounding (GOS) have been applied to study the electromagnetic response of the rift structure of the Rhine Graben. The measurements at 17 MT and 7 GOS stations were carried out along a profile running perpendicular across the Graben. Fourier analysis and numerical filters were tried for separation of the frequencies and a least squares technique was applied for data reduction. The thus gained transfer functions can be explained well by two-dimensional models under the following assumption: a well conducting layer at the depth between about 80 and 100 km exists at distances 50 km West and 100 km East of the Rhine Graben. Immediately below the Graben, however, a zone of similar good conductivity lies between about 25 and 45 km depth. The lateral extension of this zone is only some tens of km from the Graben's edges.           ARK: https://n2t.net/ark:/88439/y032853 Permalink: https://geophysicsjournal.com/article/276 &nbsp

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