HR: 0800h
AN: T31A-1272    [Abstracts]
TI: SE Carpathins - unique continental collision?
AU: * Mocanu, V I
EM: mocanu@gg.unibuc.ro
AF: University of Bucharest, 6, Traian Vuia Street, Bucharest, 020956 Romania
AB: The Carpathians are a key zone for understanding the post-collisional fate of subducted lithosphere which can only be observed and monitored on a very few spots on the Earth. The slab detachment (?) and the following sinking of the detached lithosphere slab into the deeper mantle are strictly restricted to a few million years. The detachment process itself is rarely observable and not really understood. It is not clear whether the detachment takes place in form of brittle failure suddenly removing the slab or whether visco-elastic processes play a relevant role, so that the detachment is not a real "break", but more likely a long-winded elongation and thinning of parts of the subducted lithosphere. The Vrancea region in the SE-Carpathians is one of the regions where to study this geodynamic process. Seismicity beneath Vrancea is characterized by strong intermediate events repeated 10 years for Mw>6.5 and 50 years for Mw>7.4. A very complex approach is clearly necessary in order to shade light on the processes associated with this very active area. Seismic investigations of the Carpathian orogen area form one component of a few multidisciplinary initiatives. The main objectives are: (1) the architecture of the Tertiary/Quaternary; (2) the presence and geometry of structural detachments; (3) the relationship between crustal structures, deeper (mantle) structure and seismicity; and (4) integration with complementary studies in the Carpathian region, the evaluation and validation of competing geodynamic models. A complex tomography experiment from 1999 shows a good resolution down to 350 km depth. The high velocity body extends between 70 km and more than 350 km, deeper than the deepest event (220 km). The 350 km are key for ocean closure reconstruction as it represents the entire lithosphere subducted in the area of SE-Carpathians. The subduction of a foreland slab is associated to surface deformation as indicated by the crustal seismicity and by leveling comparison data. Repeated GPS measurements gives information on the precise location of deformations which has important implications for determination/confirmation of the main risked areas and therefore on the future developments. In particular, we try to answer if the subducted slab has detached from the foreland plate or not. We also have information on the origin of the convergence (eastern or western plate) and about the (de)coupling of the Carpathians with the foreland plate.
DE: 7230 Seismicity and seismotectonics
DE: 8110 Continental tectonics--general (0905)
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8155 Plate motions--general
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting