Seismic anisotropy beneath the western part of the Carpathian-Pannonianregion inferred from combined SKS splitting and mantle xenolith studies
- 1MTA FI Lendület Pannon LitH2Oscope Research Group, Institute of Earth Physics and Space Science, Sopron, Hungary
- 2Institute of Earth Physics and Space Science, Sopron, Hungary
- 3Lithosphere Fluid Research Laboratory, Department of Petrology and Geochemistry, Institute of Geography and Earth Sciences, Eötvös Loránd University, Budapest, Hungary
- 4Mining and Geological Survey of Hungary, Budapest, Hungary
- 5Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria
- 6Department of Geophysics and Space Science, Institute of Geography and Earth Sciences, Eötvös Loránd University, Budapest, Hungary
- 7Tectonics Group, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, Netherlands
- *A full list of authors appears at the end of the abstract
Information on mantle anisotropy can be obtained from methods such as
studying the lattice-preferred orientation (LPO) in mantle peridotites,
or conducting shear-wave splitting (SKS) analyses which allow to
determine whether it is a single or multi-layered anisotropy and the
delay time of the fast and slow polarized wave can indicate the
thickness. In this study we provide a detailed SKS mapping on the
western part of the Carpathian-Pannonian region (CPR) using an increased
amount of splitting data, and compare the results with seismic
properties reported from mantle xenoliths to characterize the depth,
thickness, and regional differences of the anisotropic layer in the
mantle.
According to the combined SKS and xenolith data, mantle anisotropy is
different in the northern and the central/southern part of the western
CPR. In the northern part, the lack of azimuthal dependence of the fast
split S-wave indicates a single anisotropic layer, which agrees with
xenolith data from the Nógrád-Gömör volcanic field. In the central
areas, multiple anisotropic layers are suggested by systematic azimuthal
variations in several stations, which may be explained by two,
petrographically and LPO-wise different xenolith subgroups described in
the Bakony-Balaton Highland. The shallower layer is suggested to have a
‘fossilized’ lithospheric structure, which could account for the
occasionally detected E-W fast S-orientations, whereas the deeper one
reflects structures responsible for the regional NW-SE orientations
attributed to the present-day convergent tectonics. In the Styrian
Basin, results are ambiguous as SKS splitting data hints at the presence
of multiple anisotropic layers, however, it is not supported clearly by
xenolith data.
Spatial coherency analysis of the splitting parameters put the center of
the anisotropic layer at ~140-150 km depth under the Western
Carpathians, which implies a total thickness of ~220-240 km. Thickness
calculated from seismic properties of the xenoliths resulted in lower
values on average, which may be explained by heterogeneous sampling by
xenoliths, or the different orientation of the mineral deformation
structures (foliation and lineation).
AlpArray Working Group
How to cite: Liptai, N., Gráczer, Z., Szanyi, G., Süle, B., Aradi, L., Falus, G., Bokelmann, G., Timkó, M., Timár, G., Cloetingh, S., Szabó, C., and Kovács, I. and the AlpArray Working Group: Seismic anisotropy beneath the western part of the Carpathian-Pannonianregion inferred from combined SKS splitting and mantle xenolith studies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13364, https://doi.org/10.5194/egusphere-egu22-13364, 2022.
