HR: 10:50h
AN: S52B-03    [Abstracts]
TI: Data From Massive Seismic Experiments in Central Europe Produce Lithospheric Transects From East European Craton Through the TESZ, Bohemian Massif and Carpathians to the Pannonian Basin and Eastern Alps
AU: Guterch, A
AF: Polish Academy of Sciences, Institute of Geophysics KS. Janusza 64, Warsaw, 01-452 Poland
AU: Grad, M
EM: mgrad@mimuw.edu.pl
AF: University of Warsaw, Institute of Geophysics Pasteura 7, Warsaw, PL 02-093 Poland
AU: * Keller, G R
EM: keller@utep.edu
AF: University of Texas at El Paso, Dept of Geological Sciences, El Paso, TX 79968 United States
AU: Brueckl, E
EM: ebrueckl@luna.tuwien.ac.at
AF: Vienna University of Technology, Insitute of Geodesy and Geophysics Gusshausstrasse 27-29, Vienna, A-1040 Austria
AU: Hegedus, E
EM: elgi@elgi.hu
AF: Eotvos Lorand Geophysical Institute, Kolumbusz u. 17-23, Budapest, H-1145 Hungary
AU: Spicak, A
EM: als@ig.cas.cz
AF: Academy of Sciences of the Czech Republic, Geophysical Institute Bocni II 1401, Prague 4, 141 32 Czech Republic
AU: Vozar, J
EM: jvozar@gssr.sk
AF: Slovak Academy of Sciences, Geological Institute Dubravska cesta 9, Bratislava, 840 05 Slovakia (Slovak Republic)
AB: A series of very large seismic refraction experiments (POLONAISE'97, CELEBRATION 2000, ALP 2002, SUDETES 2003) began in 1997 in Central Europe. As a result of these efforts, a large region has been covered by an unprecedented network of profiles and with 3-D coverage. The total length of all the profiles is about 19,000 km and over 300 explosive sources were recorded. This network of profiles extends from the East European Craton (EEC) across the bounding Trans-European suture zone TESZ) to traverse the adjacent Bohemian massif, Carpathian Mountains, Pannonian basin and Eastern Alps. Analysis and modeling of the two longest profiles (P4 from POLONAISE'97 $\sim$1000 km long and CEL05 from CELEBRATION 2000 $\sim$1400 km long) produced synoptic lithospheric velocity models. The variations in lithospheric structure across the region are large and complex. For example, the crustal thickness changes from 22-25 km in the Pannonian basin to $\sim$55 km in the Trans-European suture zone in SE Poland to $\sim$50 km in the EEC. Regionally, the most complicated structure observed is in the transition from the Pannonian basin to the EEC. The sedimentary cover with velocities Vp$<$5.5 km/s reaches a maximum depth $\sim$20 km in this region. In the Pieniny Klippen belt (boundary between the Inner and Outer Carpathians), a low velocity sedimentary slab dips towards the south at 35-40o to a depth of 10 km. In the TESZ area along profile CEL05, all of the crustal layers are upwarped producing high velocities ($\sim$6.4 km/s) at a depth of only $\sim$10 km. Since good quality record sections were obtained to offsets of $\sim$600 km from the shot points, clear reflected/refracted arrivals from the lithospheric mantle were observed. Two-dimensional interpretation of the reversed system of travel-times constrains a series of reflectors in the depth range of 50-90 km that dip to the north suggesting northward subduction or a younger thermal feature. To the north along profile P4, the Paleozoic platform and EEC are divided by the Polish basin. In the area of the Polish basin, the P wave velocity is very low ($<$ 6.1 km/s) down to depths of 15-20 km, indicating that a very thick sedimentary sequence is present. We suggest two possible tectonic interpretations of the velocity models: (1) Baltica indented Avalonia, obducting its upper crust and underthrusting its lower crust and (2) a rifted margin of Baltica underlies the Polish basin. The CEL03 profile is parallel to the TESZ and demonstrates that crustal variations along the feature are as complex as the ones along it. This profile suggests that several terranes lie along the TESZ but whether they are silvers of Baltica or Gondwanan in origin remains to be determined. Together all these experiments are providing an unprecedented 3-D image of the lithospheric structure of the Central Europe, which has major tectonic implications.
UR: http://paces.geo.utep.edu
DE: 7205 Continental crust (1242)
DE: 7218 Lithosphere and upper mantle
DE: 0905 Continental structures (8109, 8110)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting