HR: 0800h
AN: T51C-1359    [Abstracts]
TI: Discriminating Between Subhorizontal Lower Crustal and Upper Mantle Reflectivity to Delineate Moho Geometry Under the Transylvanian Basin, Romania
AU: * Fillerup, M A
EM: mfillerup@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, Columbia, SC 29208 United States
AU: Knapp, J H
EM: knapp@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, Columbia, SC 29208 United States
AU: Knapp, C
EM: camelia@geol.sc.edu
AF: Department of Geological Sciences, University of South Carolina, Columbia, SC 29208 United States
AB: A thick interval (~16 km) of reflective layered material at the crust/mantle boundary beneath the Transylvanian Basin, Romania, complicates delineation of the Mohorovicic discontinuity based on the deep seismic reflection method. Seismic reflection data from DRACULA I, collected during Project DRACULA (Deep Reflection Acquisition Constraining Unusual Lithospheric Activity), correlated with existing deep (17 s) industry reflection data constrains this regional subhorizontal fabric and may show a genetic relationship to the Vrancea Seismogenic zone. Portions of the DRACULA I line exhibit subhorizontal reflectivity in excess of 25 seconds (~75 km) with no clear reflective break indicating probable Moho location. Other bright reflectors in the southeastern end of DRACULA I at 7-10 seconds TWTT may represent the westward continuation of structural detachments from the Eastern Carpathians. The subhorizontal laterally continuous 10-17 second TWTT crust/mantle reflective interval is the most pervasive feature observed on all the profiles used in this study, and shows continuity of the Transylvanian crust into the Eastern Carpathians. The subhorizontal nature of this crust/mantle reflective interval seems to preclude the existence of a former Miocene-age suture zone to account for Miocene subduction as currently proposed for the geodynamic setting of the Vrancea seismogenic zone. A continuous lower crust without a plate boundary beneath the Transylvanian Basin advocates the less invasive process of active continental lithospheric delamination as a means to explain the Vrancea seismicity. Although still preliminary, results from the DRACULA I and supporting industry profiles, speak strongly against Miocene-age northwestward subduction in the Southeast Carpathians to be responsible for the intermediate-depth seismicity.
DE: 8100 TECTONOPHYSICS
SC: Tectonophysics [T]
MN: Fall Meeting 2005