HR: 0800h
AN: T51C-1358    [Abstracts]
TI: Neotectonic Southeast Carpathian Foreland Deformation and Genetic Association with the Vrancea Seismogenic Zone
AU: * Mucuta, D M
EM: dmucuta@geol.sc.edu
AF: Dept. Geological Sciences, University of South Carolina, 701 Sumter Street, Columbia, SC 29208 United States
AU: Knapp, C C
EM: camelia@geol.sc.edu
AF: Dept. Geological Sciences, University of South Carolina, 701 Sumter Street, Columbia, SC 29208 United States
AU: Knapp, J H
EM: knapp@geol.sc.edu
AF: Dept. Geological Sciences, University of South Carolina, 701 Sumter Street, Columbia, SC 29208 United States
AU: Mocanu, V
EM: mocanu@gg.unibuc.ro
AF: Faculty of Geology and Geophysics, University of Bucharest, 6 Traian Vuia St., Bucharest, 70139 Romania
AU: Raileanu, V
EM: raivic@infp.ro
AF: National Institute for Earth Physics, Bucharest-Magurele, PO Box MG-2, Bucharest, 077125 Romania
AB: Three deep (18-20 s TWTT), industry type seismic reflection profiles and the DRACULA II (Deep Reflection Acquisition Constraining Unusual Lithospheric Activity) multichannel transect (30 s), collected in the southeast Carpathian foreland basin were processed targeting crustal and upper mantle structures that could substantiate a genetic and geometric association between the ongoing foreland deformation and the seismically active Vrancea zone. Of specific interest was the imaging of (1) active crustal faults, possibly offsetting the Moho, (2) geometry of crustal reflectors, and (3) position and geometry of the Moho. These features are viewed as essential in differentiating between existing models (subduction of oceanic lithosphere versus delamination of continental lithosphere) explaining intermediate-depth (50-210 km) seismicity in the SE Carpathians. In the central-southern part of the Focsani basin, two combined profiles oriented W-E document (1) a gently eastward dipping Moho at a depth of 42-45 km, (2) a dramatic increase in the sedimentary cover from 14 km (W) to less than 1 km (E), (3) interpreted normal faults with surface offsets, some cutting the crystalline basement, (4) horizontal mid-crustal reflectivity, and (5) the absence of prominent west dipping reflectors expected from the subduction model. A NNW-SSE oriented profile located in the southern extreme of the basin shows (1) 7-10 km sediment fill, (2) a crust-mantle transition zone between 42-38 km, (3) similar mid-crustal horizontal packages of reflectors, and (4) intense basement fracturing with some faults possibly active and propagating to the surface. DRACULA II profile was acquired in the summer of 2004 with the purpose of imaging structures over the seismically active crustal scale Peceneaga-Camena fault, in the northern extremity of the basin. It displays unusual reflective sequences down to 15 s (45 km) where we interpret the Moho on the eastern side but a seemingly transparent crust on the western side, possibly a result of the depth extent of the Peceneaga-Camena fault. No clear offsets are imaged in the shallow section but seismic activity suggests a recent reactivation of this fault. To a first order, the recent deformation, localized subsidence, and crustal seismic activity of the SE Carpathian foreland may favor delamination of the continental mantle lithosphere as a viable mechanism to produce the intermediate-depth Vrancea seismicity.
DE: 8104 Continental margins: convergent
DE: 8107 Continental neotectonics (8002)
DE: 8110 Continental tectonics: general (0905)
SC: Tectonophysics [T]
MN: Fall Meeting 2005