Interpretation of subhorizontal crustal reflections by metamorphic and rheologic effects in the eastern part of the Pannonian Basin

Károly Posgay, Tamás Bodoky, Z. Hajnal, Tivadar M. Tóth, Tamás Fancsik, E. Hegedűs, Attila Cs Kovács, Erno Takács

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The geologic origin of subhorizontal reflections, often observed in crustal seismic sections, was investigated by establishing metamorphic facies and strength of rocks in depth, and correlating these properties to seismic reflection sections from eastern Hungary. Estimation of the depths of metamorphic mineral stability zones utilized the principles developed by Fyfe et al. and known geothermal data of the area. The strength versus depth profile was derived by relating local seismic P-wave interval velocities to Meissner et al.'s activation energy. The results show that the series of subhorizontal reflections, observed in the Pannonian Basin, are a consequence of combined metamorphic and rheologic changes in depths. The synthesis of the integrated data set suggests that the retrograde alteration of the pre-Tertiary basement above the percolation threshold was made possible by the softening effect of shear zones and their water-conducting capacity. The subhorizontal reflections of highest energy, of the consolidated crust below the percolation threshold, originate in the depths of greenschist, amphibolite and granulite metamorphic mineral facies, which were formed in geothermal and pressure conditions similar to those existing today. These results imply the overprint of earlier (Variscan) metamorphic sequences of the crust by more recent retrograde metamorphic processes.

Original languageEnglish
Pages (from-to)187-203
Number of pages17
JournalGeophysical Journal International
Volume167
Issue number1
DOIs
Publication statusPublished - Oct 2006

Fingerprint

basin
Minerals
crusts
minerals
crust
metamorphic facies
Hungary
thresholds
greenschist
mineral
granulite
amphibolite
softening
basements
Hercynian orogeny
P waves
Activation energy
seismic wave
activation energy
Rocks

Keywords

  • Crustal structure
  • Metamorphism
  • Rheology
  • Seismic structure

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Interpretation of subhorizontal crustal reflections by metamorphic and rheologic effects in the eastern part of the Pannonian Basin. / Posgay, Károly; Bodoky, Tamás; Hajnal, Z.; Tóth, Tivadar M.; Fancsik, Tamás; Hegedűs, E.; Kovács, Attila Cs; Takács, Erno.

In: Geophysical Journal International, Vol. 167, No. 1, 10.2006, p. 187-203.

Research output: Contribution to journalArticle

Posgay, Károly ; Bodoky, Tamás ; Hajnal, Z. ; Tóth, Tivadar M. ; Fancsik, Tamás ; Hegedűs, E. ; Kovács, Attila Cs ; Takács, Erno. / Interpretation of subhorizontal crustal reflections by metamorphic and rheologic effects in the eastern part of the Pannonian Basin. In: Geophysical Journal International. 2006 ; Vol. 167, No. 1. pp. 187-203.
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