The authors have attempted to interpret the origin of subhorizontal reflections often observed in crustal seismic sections. They have compared the approximate locations of metamorphic facies and the probable strength of the rocks depending on depth to a few seismic sections of eastern Hungary. Estimation of depth of metamorphic mineral stability zones was carried out by the data of Fyfe et al. (1978) and geothermal data of the area. The strength profile was computed by the diagram of Meissner et al. (1991) and the seismic P-wave interval velocities determined in the region. The authors conclude that the series of subhorizontal reflections are connected to metamorphism and strength envelopes, and may even be of importance in interpreting industrial seismic sections. The examples presented in their paper suggest that the retrograde metamorphism of the pre-Tertiary basement was made possible by the softening effect of shear zones and their water-conducting capacity. It was found that the subhorizontal reflections of highest energy in the consolidated crust are to be found in the depths of greenschist, amphibolite and granulite metamorphic mineral facies originating in geothermal and pressure conditions similar to the present ones. Thus the overprint of earlier (Variscan) metamorphic structure by a retrograde metamorphism can be supposed.
|Number of pages||22|
|Journal||Acta Geologica Hungarica|
|Publication status||Published - Jan 1 2001|
- Deep seismic survey
- P-wave velocity
- Subhorizontal reflections
ASJC Scopus subject areas