HR: 1330h
AN: T52B-0255    [PDF]
TI: Combined Interpretation of Receiver Functions and Rayleigh Phase Velocities: Implications for Lithospheric Structure in the Area of Crete (Greece)
AU: * Endrun, B
EM: endrun@geophysik.rub.de
AF: Ruhr-University Bochum, Dept. GMG Universitaetsstr. 150, Bochum, 44780 Germany
AU: Meier, T
EM: meier@geophysik.rub.de
AF: Ruhr-University Bochum, Dept. GMG Universitaetsstr. 150, Bochum, 44780 Germany
AU: Bischoff, M
EM: bischoff@geophysik.rub.de
AF: Ruhr-University Bochum, Dept. GMG Universitaetsstr. 150, Bochum, 44780 Germany
AU: Harjes, H
EM: harjes@geophysik.rub.de
AF: Ruhr-University Bochum, Dept. GMG Universitaetsstr. 150, Bochum, 44780 Germany
AB: We investigate the lithosperic structure in the forearc of the Hellenic subduction zone from the surface to the depth of the subducted African Moho by Rayleigh fundamental mode dispersion and teleseismic receiver functions. Both methods are primarily sensitive to the S-velocity distribution, but also complement each other: Receiver functions can outline sharp velocity discontinuities, but contain no absolute velocity information, while the shape of Rayleigh phase velocity curves depends mainly on the average S-velocity. A combined interpretation of the consistent results from both methods points to significant lateral variations in structure between western and central Crete. We use data from several temporary short-period networks on Crete as well as from permanent GEOFON broadband-stations in the southern Aegean. Short-period data from dense networks broaden the frequency range available for phase velocity determination and increase the spatial coverage of receiver function profiles. Beneath Crete, we find evidence of two Mohos, the continental Aegean Moho and the oceanic Moho of the subducted African lithosphere. The African Moho can be imaged continuously at 55 km depth by both methods. An intracrustal discontinuity is observed in both western and central Crete at depths between 10 and 20 km. Below, western Crete is characterized by nearly constant crustal S-velocities to a depth of 50 km and no distinct continental Moho signal. Central Crete shows crustal velocities down to about 30 km depth which are followed by the Aegean Moho and a region with upper mantle velocities above the slab. This means that the slab is separated from the Aegean crust by a mantle wedge beneath central Crete, while beneath western Crete a thickened crustal region extends down to the subducted oceanic lithosphere at 50 km depth. This thickened crust is interpreted as indication of return-flow in a subduction channel. Besides, lateral variations among receiver function waveforms indicate structural heterogeneity between 25 and 45 km depth below western Crete.
DE: 7218 Lithosphere and upper mantle
DE: 7255 Surface waves and free oscillations
DE: 8105 Continental margins and sedimentary basins
SC: Tectonophysics [T]
MN: 2003 Fall Meeting