Modelling of the conductance distribution at the eastern margin of the European Hercynides
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
Magnetic variation data recorded at 143 sites in the period range of 1000–6000 seconds were used to model the conductance distribution in the eastern part of the Bohemian Massif (BM) and the West Carpathians (WCP). The region represents a contact zone of the Palaeozoic Hercynian and Tertiary Carpathian orogenic systems. Two anomalies in the distribution of the electrical conductivity were found. One with a simple two-dimensional feature is located approximately near the boundary of the Inner and Outer West Carpathians, but the other of a complicated three-dimensional character is at the eastern margin of the BM. We inverted the observed geomagnetic data for the conductance in a unimodal thin sheet embedded at a specific depth. The inversion algorithm minimises the parametric functional that sums the squared norm of the misfit and the stabilising functional, and employs conjugate gradient optimisation. To express the sharp tectonic boundaries, we employed a minimum gradient support functional, which is applied in areas with strong variations of the model parameters. The inversion results confirmed a quasi-linear character of the regional anomaly distinguishing the Carpathian plate and led to new insight into the anomaly over the eastern margin of the BM. According to the results of the modelling the anomaly is formed by several conductive belts intersecting the anomalous zone. These belts follow important faults, dividing the transition zone between the BM and the WCP into individual blocks.
- Aubouin J., 1980. Geology of Europe: A synthesis. Episodes, 1, 3–8.
- Avdeev D.B., Kuvshinov A.V. and Pankratov O.V., 1998. An imaging of buried anomalies using multi-sheet inversion. Earth Planets Space, 50, 417–422.
- Bailey R.C., Edwards R.N., Garland G.D., Kurz R. and Pitcher D., 1974. Electrical conductivity studies over a tectonic active area in Eastern Canada. J. Geomagn. Geoelectr., 26, 125–146.
- Banks R.J., 1978. The use of the equivalent current systems in the interpretation of the geomagnetic deep sounding data. Geophys. J. R. Astr. Soc., 56, 139–157.
- Banks R.J., 1986. The interpretation of the Northumberland Trough geomagnetic variation anomaly using two-dimensional current model. Geophys.J. R. Astr. Soc., 87, 595–616.
- Banks R.J. and Ritter P., 1998. Separation of local and regional information in distorted GDS response functions by hypothetical event analysis. Geophys. J. Int., 153, 923–942.
- Berdichevski M.N. and Zhdanov M.S., 1984. Advanced Theory of Deep Geomagnetic Sounding. Elsevier, Amsterdam-Oxford-New York-Tokyo, 11–25, 194–203.
- Cerv V., Kovacikova S., Pek J., Pecova J. and Praus O., 1997. Model of electrical conductivity distribution across Central Europe. J. Geomag. Geoelectr., 49, 1585–1600.
- Cerv V., Kovacikova S., Pek. J., Pecova J. and Praus O., 2001. Geoelectrical structure across the Bohemian Massif and the transition zone to the West Carpathians. Tectonophysics, 332, 201–210. CrossRef
- Cerv V., Kovacikova S., Pek. J., Pecova J. and Praus O., 2002. Modelling of conductivity structures generating anomalous induction at the eastern margin of the Bohemian Massif and the West Carpathians. Acta Geophysica Polonica, 50(4), 527–546.
- Cerv V. and Pek J., 1981. Numerical solution of the two-dimensional inverse geomagnetic induction problem. Stud. Geophys. Geod., 25, 69–80. CrossRef
- Cerv V., Pek J. and Praus O., 1984. Models of geoelectrical anomalies in Czechoslovakia. J. Geophys., 55, 61–168.
- Cerv V., Pek J. and Praus O., 1987. Numerical modeling of geoelectrical structure in Czechoslovakia. Phys. Earth Planet. Inter., 45, 170–178. CrossRef
- Cerv V., Pek. J. and Praus O., 1990. Limitations of the unimodal thin sheet modelling of near-surface inhomogeneities in Czechoslovakia. Phys. Earth Planet. Inter., 60, 100–114. CrossRef
- Dudek A., 1980. The crystalline basement block of the Outer Carpathians in Moravia: Bruno-Vistulicum. Rozpr. Eeskosl. Akad. Ved., 90/8, 1–85.
- Hansen P.C., 1992. Analysis of discrete ill-posed problems by means of the L-curve. SIAM Review, 34, 561–580. CrossRef
- Hestenes M.R. and Stiefel E., 1952. Methods of conjugate gradients for solving linear systems. J. Res. Nat. Bureau Stand., 49, 409–436.
- Inoue H., 1986. A least-squares smooth fitting for irregularly spaced data: Finite element approach using the cubic B-spline basis. Geophysics, 51, 2051–2066. CrossRef
- Jankowski J., Tarlowski Z., Praus O., Pecova J. and Petr V., 1985. The results of deep geomagnetic soundings in the West Carpathians. Geophys. J. R. Astr. Soc., 80, 561–574.
- Mahel M., Kamenicky J., Fusan O. and Matejka A., 1967. Regional Geology of Czechoslovakia. Part II, Western Carpathians. Academia, Prague, Czech Republic, 9–19 (in Czech).
- Matte P., 1991. Accretionary history and crustal evolution of the Variscan belt in Western Europe. Tectonophysics, 196, 309–337. CrossRef
- Misar Z., Dudek A., Havlena V. and Weiss J. 1983. Geology of Czechoslovakia, Czech Massif. SSN, Prague, Czech Republic, 226–236 (in Czech).
- Pecova J., Petr V. and Praus O., 1976. Depth distribution of the electrical conductivity in Czechoslovakia from electromagnetic studies. In: A. Adam (Ed.), Geoelectric and Geothermal Studies. KAPG Geophys. Monograph, Akademiai Kiado, Budapest, Hungary, 517–537.
- Pecova J., 1982. Determination of the depth of a conductivity anomaly by separating the geomagnetic variation field into its external and internal part. Travaux Geophysique, XXX, No.575, 179–197.
- Pecova J. and Praus O., 1996. Anomalous induction zones in the Czech Republic in relation to large-scale European anomalies. Stud. Geophys. Geod., 40, 50–76.
- Portniaguine O. and Zhdanov M.S., 1999. Focussing geophysical inversion images. Geophysics, 64, 874–887. CrossRef
- Praus O. and Pecova J., 1991. Anomalous geomagnetic fields of internal origin in Czechoslovakia. Stud. Geophys. Geod., 35, 81–89. CrossRef
- Press W.H., Flannery S.A., Teukolsky S.A. and Wetterling W.T., 1988. Numerical Recipes. The Art of Scientific Computation. Cambridge Univ. Press, Cambridge, U.K.
- Suk M., 1995. Regional geological division of the Bohemian Massif. Exploration Geophysics, Remote Sensing and Environment, II(2), 25–30.
- Van Breemen O., Aftalion M., Bowes D.R., Dudek A., Misar Z., Povondra P. and Vrana S., 1982. Geochronological studies of the Bohemian Massif, Czechoslovakia, and their significance in the evolution of the Central Europe. Trans. Royal Soc. Edinburgh: Earth Sciences, 73, 89–108.
- Vasseur G. and Weidelt P., 1977. Bimodal EM induction in non-uniform thin sheets with an application to the Northern Pyrenean induction anomaly. Geophys. J. R. Astr. Soc., 51, 669–690.
- Wang L.J. and Lilley F.E.M., 1999. Inversion of magnetometer array data by thin-sheet modelling. Geophys. J. Int., 137, 128–138. CrossRef
- Wang X., 1988. Inversion of magnetovariation event to causative current: I. Current sheet model. Phys. Earth Planet. Inter., 53, 46–54. CrossRef
- Wybraniec S., Jankowski J., Ernst T., Pecova J. and Praus O., 1999. A new method for presentation of induction vector distribution in Europe. Acta Geophysica Polonica, XLVII(No 3), 323–334.
- Zytko K., 1997. Electrical conductivity anomaly of the Northern Carpathians and the deep structure of the orogen. Annales Societatis Geologorum Poloniae, 67, 25–43.
- Modelling of the conductance distribution at the eastern margin of the European Hercynides
Studia Geophysica et Geodaetica
Volume 49, Issue 3 , pp 403-421
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers-Consultants Bureau
- Additional Links
- geomagnetic deep sounding
- Bohemian Massif
- thin sheet approximation
- inversion modelling
- Industry Sectors