MAPPING THE MOHO BENEATH THE SOUTHERN URALS WITH WIDE-ANGLE REFLECTIONS

A stack of the wide-angle reflection/refraction component of the URSEI S-95 experiment provides the first well-resolved imaged of the Moho be neath the southern Urals. The processing consisted of low pass filter (0 - 6 Hz), CMP sorting, and a NMO correction without stretch. The PmP phase, a very narrow band and low frequency (up to 6 Hz) wavelet, cha nges character from west to east along the transect. In the depth conv erted section, the Moho reaches a maximum depth of 53 +/- 2 km beneath the Magnitogorsk are. Thickness estimates determined from high amplit udes at near critical distances also support a 53 km thick crust. A se lective offset stack consisting of traces at 150 - 250 km offset indic ate an undulating, irregular Moho, suggesting either strong lateral ve locity variations or high topographic relief beneath the Magnitogorsk arc.