Crustal structure of the Trans-European suture zone region along POLONAISE'97 seismic profile P4

Marek Grad*, Susanne L. Jensen, G. Randy Keller, Aleksander Guterch, Hans Thybo, Tomasz Janik, Timo Tiira, Jukka Yliniemi, Urmas Luosto, Gediminas Motuza, Viktor Nasedkin, Wojciech Czuba, Edward Gaczyński, Piotr Sroda, Kate C. Miller, Monika Wilde-Piórko, Kari Komminaho, Juozas Jacyna, Larisa Korabliova

*Bu çalışma için yazışmadan sorumlu yazar

Araştırma sonucu: Dergiye katkıMakalebilirkişi

145 Atıf (Scopus)

Özet

The large-scale POLONAISE'97 seismic experiment investigated the velocity structure of the crust and upper mantle in the Trans-European suture zone (TESZ) region between the Precambrian east European craton (EEC) and Paleozoic platform that comprises terranes added during the Caledonian and Variscan orogenies (530-370 and 370-225 Ma, respectively). This experiment included 64 shots recorded by 613 seismic stations during two deployments. Very good quality data were recorded along five profiles, and the longest and most important one (P4) is the focus of this paper. Clear first arrivals and later phases of waves reflected/refracted in the crust and Moho were interpreted using two-dimensional (2-D) tomographic inversion and ray-tracing techniques. The crustal thickness along the profile varies from 30-35 km in the Paleozoic platform area to ∼40 km below and due northeast of the TESZ, to ∼43 km in the Polish part of the EEC, and to ∼50 km in Lithuania. The Paleozoic platform and EEC are divided by the Polish basin, so the upper crustal structure varies considerably. In the area of the Polish basin, the P wave velocity is very low (VP < 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 in a tectonic flake structure and (2) a rifted margin of Baltica underlies the Polish basin. This model is similar to other interpretations of seismic profiles recorded in the Baltic Sea. The second model implies that the Paleozoic platform solely consists of Avalonian lithosphere and the EEC of Baltica lithosphere. It offers a simple explanation of the difference in crustal thickness of the two platforms. It also implies that the Caledonian and Variscan orogenies in this area were relatively "soft" collisions that left this continental margin largely intact.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)ESE 12-1 - ESE 12-24
DergiJournal of Geophysical Research: Solid Earth
Hacim108
Basın numarası11
Yayın durumuYayınlandı - 10 Kas 2003
Harici olarak yayınlandıEvet

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