HR: 0800h
AN: T41E-1346    [Abstracts]
TI: Seismic Reflection Imaging and Modeling of Deep (13-16 Km) Fault-bend folds Within the Deformed Sedimentary cover of the South Caspian Basin
AU: * Asencio, E
EM: asencio@uprm.edu
AF: Department of Geology University of Puerto Rico, P.O. Box 9017, Mayaguez, PR 00680 Puerto Rico
AU: Knapp, J H
EM: knapp@geol.sc.edu
AF: Geological Sciences University of South Carolina, Sumter Street, Columbia, SC 29208 United States
AB: We present new observational evidence for a detachment at depth within the sedimentary cover of the South Caspian Basin in seismic reflection profiles and the regional satellite-altimetry gravity data. Our study establishes the viability of imaging and mapping the deformed sedimentary cover using deep seismic reflection and three-dimensional Eulers deconvolution methods. Deep seismic reflection profiles image a(19-22 km thick) sequence of sediments structurally deformed into symmetrical folds. We interpret these observations as fault-bend folds overriding a regional ductile detachment zone at a depth of about 13 to 16 km. Deformation of the sedimentary cover above the detachment zone was mapped using the Eulers deconvolution method of the regional satellite-altimetry gravity data. Regional features trending N-S, NW-SE and NE-SW cluster at a depth interval of 7.5-15 km and are interpreted as trends of structural boundaries (faults or steeply dipping contact) within the sedimentary cover. The geophysical data also provide evidence of a (~13 km) thick lower crust of mafic bulk composition with densities of ~2.9 gm/cc. This lower crust is relatively undeformed, except at the bordering seismogenic belts north of the Apsheron-Balkan Sill prolongation, along the Azerbaijan-Iran border and off the north coast of Iran. Our analyses of the geophysical data in comparison to well documented earthquake focal mechanisms, centroid depths, and GPS velocity field measurements suggest the possibility that the present-day pattern of deformation of the overlying sedimentary cover within the South Caspian Basin is in response of a component of right lateral shear between the underlying crust of the South Caspian Basin and the central and western Caucasus.
DE: 1209 Tectonic deformation (6924)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 8106 Continental margins: transform
DE: 8122 Dynamics: gravity and tectonics
SC: Tectonophysics [T]
MN: Fall Meeting 2005