From the very beginning of the magnetotelluric (MT) studies two notions have been coupled to each other: the graphite as one of the causes of strong conductivity anomalies and tectonics. The graphitic formations of very low resistivity (< 10-1 Wm) are accumulated in the shear zones, thrust sheets, detachment horizon etc.\ and by this way they indicate the tectonics/paleotectonics which may not be indicated by other geophysical method so definitely. The author firstly surveys the manifestation of this phenomenon in case histories of the literature, then illustrates it by own very detailed study carried out on the Transdanubian crustal conductivity anomaly (TCA). The material of the conductor and their possible relation to the seismicity of the area will also be demonstrated by the TCA anomaly. In the closing chapters the origin of the graphite and its accumulation in the shear zones is discussed including the role of the (geothermal) water.
In this column Periodica Mathematica Hungarica publishes current research problems whose proposers believe them to be within reach of existing methods. Manuscripts should preferably contain the background of the problem and all references known to the author. The length of the manuscripts should not exceed two double-spaced type-written pages.
Two effects have been studied concerning the former Wiese arrows and the newly determined complex induction vectors in the Pannonian backarc basin (Hungary): the remote effect of the curved Carpathian Conductivity Anomaly (CA) on the direction of the long period vectors, the local effect of the thickness (or conductance) of the conductive sediments on the induction vectors. The curvature of the Carpathian CA is clearly seen in the direction of the induction vectors as a remote effect dividing the Pannonian Basin into two great parts from this point of view. Following Zhang et al. (1993) who stated that the length (absolute value) of the induction vector becomes also constant in the “S-interval” as the magnetotelluric (MT) impedance which is related to the conductance of the sedimentary cover, it has been studied whether there is also any relation between the length of the induction vectors and the conductance of the same sedimentary cover (or thickness of sediment if its resistivity is constant). Due to the structural inhomogeneities to which the induction vectors are very sensitive, and to their great remote (side) effect, only a weak statistical relation has been found, nevertheless, its trend could be approximated by Ritter and Banks' (1998) theory. Exceptional cases are demonstrated.