The crust-mantle transition and the Moho beneath the Vogtland/West Bohemian region in the light of different seismic methods |
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| Authors: | Pavla Hrubcová Wolfram H Geissler |
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| Institution: | (1) Institute of Geophysics, Acad. Sci. Czech Republic, Boční II/1401, 141 31 Praha 4, Czech Republic;(2) Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, 27568 Bremerhaven, Germany |
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| Abstract: | The structure of the crust and the crust-mantle boundary in the Vogtland/West Bohemian region have been a target of several
seismic measurements for the last 25 years, beginning with the steep-angle reflection seismic studies (DEKORP-4/KTB, MVE-90,
9HR), the refraction and wide-angle experiments (GRANU’95, CELEBRATION 2000, SUDETES 2003), and followed by passive seismic
studies (receiver functions, teleseismic tomography). The steep-angle reflection studies imaged a highly reflective lower
crust (4 to 6 km thick) with the Moho interpreted in a depth between 30 and 32 km and a thinner crust beneath the Eger Rift.
The refraction and wide-angle reflection seismic studies (CELEBRATION 2000) revealed strong wide-angle reflections in a depth
of 26–28 km interpreted as the top of the lower crust. Long coda of these reflections indicates strong reflectivity in the
lower crustal layer, a phenomenon frequently observed in the Caledonian and Variscan areas. The receiver function studies
detected one strong conversion from the base of the crust interpreted as the Moho discontinuity at a depth between 27 and
37 km (average at about 31 km). The discrepancies in the Moho depth determination could be partly attributed to different
background of the methods and their resolution, but could not fully explain them. So that new receivers function modelling
was provided. It revealed that, instead of a first-order Moho discontinuity, the observations can be explained with a lower
crustal layer or a crust-mantle transition zone with a maximum thickness of 5 km. The consequent synthetic ray-tracing modelling
resulted in the model with the top of the lower crust at 28 km, where highly reflective lower crustal layer can obscure the
Moho reflection at a depth of 32–33 km. |
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| Keywords: | Bohemian Massif Vogtland/West Bohemia crustal structure Moho refraction and wide-angle reflection receiver function seismic methods Eger Rift |
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