Upper Mantle Structure Beneath the Bohemain Massif, Central Europe - Another Baby Plume?
Abstract
The BOHEMA project (BOhemian Massif HEterogeneity and Mantle Anisotropy) has brought together geophysicists from 10 institutions in the Czech Republic, Germany and France for a joint study of the structure and dynamics of the lithosphere and asthenosphere in the geodynamically active western part of the Bohemian Massif. An array of seismic stations covered a territory of approx. 270x150 km, with its long axis oriented perpendicularly to the strike of major tectonic units and to the Eger Rift. The network consisted of 61 permanent and 92 temporary stations operating between October 2001 and the end of 2003, with a core of recordings in 2002. Three-component short-period stations represent about 1/3 of the network, while broad-band stations constitute the remaining 2/3. Spacing of stations was generally less than 30 km, while in the central part of the array the station spacing was as small as 10-15 km, hence allowing for a lateral spatial resolution of approx. 20km in the upper mantle. The BOHEMA project aims at showing an existence or non-existence of a mantle plume beneath the Eger Rift, similarly to what has been established for several regions belonging to the European Cenozoic rift system (e.g., in Massif Central, Eifel), which may have a common source of volcanism in the mantle. Preliminary results of the P-velocity tomography indicate an asthenospheric upwelling beneath the region of Marianske Lazne. Besides isotropic velocity tomography, intensive research of body wave anisotropy is conducted. Evaluated parameters of seismic anisotropy are inverted jointly to retrieve a 3D self-consistent anisotropic model of the upper mantle, particularly of different mantle lithosphere domains. Both P- and S-wave anisotropy show two different orientations of the large-scale fabric in the Saxothuringian and the Moldanubian with a transitional type in the northern part of the Tepla-Barrandian.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.T13A0446A
- Keywords:
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- 8110 Continental tectonics: general (0905);
- 8162 Rheology: mantle (8033)