Regional magnetotelluric (MT) anisotropy in the Pannonian Basin (Hungary)

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23 Citations (Scopus)

Abstract

The deep MT sounding curves measured in the Pannonian Basin inside the Carpathian arcs show anisotropy characterized by the following features: _ The extreme MT sounding curves (Rhomax and Rhomin) strongly differ from each other from the S-interval on, i.e. in the increasing branch of the MT curves characterizing the resistive crystalline basement of the sedimentary cover. Rhomin curves give for the resistivity of the basement extremely low values. _ Directions of Rhomax values are near to N-S or NNW-SSE. _ The apparent depths to the conductive asthenoephere derived from Rhomax and Rhomin curves are very different. In the case of Rhomax curves - except a few very Isotropic areas - it is ≥ 100 km and in case of Rhomin, as shallow as ≤ 50 km. Their geometric mean better approximates the depths measured by seismological method and calculated from geothermal data in the hot Pannonian Basin with a heat flow of about 100 mWm-2. _ Extreme local basement structures like deep narrow extensional 3D basins (e.g. Békés graben) do not change this character of MT curves at long periods. _ A numerical model with anisotropic basement resistivity does not completely explain these features. The main source can probably be found in the E(ENE)-W(WSW) directed deep crustal fractures cutting through the whole crust and forming basin and range structure.

Original languageEnglish
Pages (from-to)191-216
Number of pages26
JournalActa Geodaetica et Geophysica Hungarica
Volume31
Issue number1-2
Publication statusPublished - Dec 1 1996

Keywords

  • Anisotropy
  • Asthenosphere
  • Conductivity anomaly
  • Deep sounding
  • Magnetotellurics
  • Numerical modeling
  • Tectonics

ASJC Scopus subject areas

  • Building and Construction
  • Geophysics
  • Geology

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