Indication of meta-anthracite by magnetotellurics in the Kőszeg-Rechnitz Penninic window: a test area

Abstract

One of the Penninic Nappes is the Kőszeg-Rechnitz (K-R) tectonic window at the Eastern end of the Eastern Alps. It has a complicated metamorphic history from the Jurassic time. The organic material of the Penninic Ocean was transformed to electrically conductive meta-anthracite. Its amount in the chalcophyllite is estimated by geochemists to 0.2 per cent.Taking this conducting structure as a test area pilot deep magnetotelluric (MT) soundings have been carried out and we determined the structure of the conductivity anomaly due to 0.2 per cent meta anthracite in the K-R window and its surroundings the different kinds of MT distortions as lateral (side) effect of the conductor appearing in the crust and mantle the most probable depth of the conductive asthenosphere at the border of the Pannonian Basin (having extreme shallow asthenosphere). The obtained ∼140 km depth is in correlation with value of the asthenospheric map based mainly on seismic data.