Seismic and geological structure of the crust in the transition from Baltica to Palaeozoic Europe in SE Poland-CELEBRATION 2000 experiment, profile CEL02

The crustal thickness along CEL02 varies from 32-35 km in the USB to 45-47 km beneath the TESZ and the EEC. The USB is a clearly distinctive crustal block with the characteristic high velocity lower crust (7.1-7.2 km/s), interpreted as a fragment of Gondwana. The Kraków-Lubliniec Fault is a terrane boundary produced by soft docking of the USB with the MB. The Małopolska crust fundamentally differs from the USB and has a strong connection with Baltica. It is a transitional, 150- to 200-km wide unit composed of the extended Baltican lower crust and the overlying low velocity (5.15-5.9 km/s) Neoproterozoic metasediments in the up to 18-km thick upper crust. The Łysogóry Unit has its crustal structure identical with that of Małopolska, thus it is connected with Baltica and cannot be interpreted as a Gondwana-derived terrane. Higher velocity and density bodies found below the Mazovia-Lublin Graben at a depth of ∼12 km and at the base of the lower crust, might be a result of mantle-derived mafic intrusions accompanying the extension of Baltica. By the preliminary 2D gravity modelling, we have reconfirmed the need for considering the increased TESZ mantle density in comparison to the EEC and USB mantle.