Integrated geophysical - rheological model of The Trans-European Suture Zone (TESZ) in NW Poland
Abstract
In the NW Poland several crustal-scale units of different age merge and overlap, creating complex and contrasting tectonic pattern. The crustal thickness changes significantly from about 30 km beneath Paleozoic platform (PP)to 42-45 km beneath the East European Ctraton (EEC. Below the subsidence center of the Permo-Mesozic Polish trough, developed along the edge of the EEC, relatively low velocities are observed down to 18-20 km depth. Seismic reflection data show that deep crustal boundaries influenced evolution of the basin. The lower crust of the PP is characterized by high velocity gradient and high reflectivity. Gravity and magnetic data suggest that Earth's crust in the study area is characterized by two significant lineaments: the first, related to the SW edge of the upper and middle(?) crust of the EEC and the second, being possibly continuation of the Thor Suture on the Polish territory. Gravity data indicate also the presence of high density bodies within the upper crust associated with intrusions of dense basic rocks. Increased densities of the lower crust and upper mantle within TESZ may be related to magmatic underplating. Heat flow data, heat generation and thermal conductivity models, numerical modelling of the crustal temperatures show evidence of extensive crustal-mantle warming in the area beneath the PP and SW part of the TESZ. Thermal lithospheric thickness is only 100 km in this area in contrast to 200 km plus for the EEC. Significant lateral rheological contrasts were modelled along the LT-7 deep seismic profile with extremely weak transition zone from the TESZ to the PP. The EEC and the NE portion of the TESZ consist of three or four strong layers that might be mechanically welded together. Along the rest of the profile two strong layers were recognised (uppermost crust and uppermost mantle), which are mechanically separated from weak lower (and middle) crust.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....1725G