Upper mantle structure along supper-long profile METEORITE (Siberian craton) carried out with peace nuclear explosion
Category: 13-4
UDC 530.34
G.A. Pavlenkova
Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
Abstract
The long-range profile Meteorite crosses the Siberian Craton and the Baikal rift zone. It was shot with 4 nuclear explosions. The seismic records of the nuclear-explosions revealed new peculiarities of the craton upper-mantle structure. The uppermost mantle is characterized velocity variation from 7.8–8.0 km/s beneath the Baikal zone to 8.1–8.5 km/s beneath the Siberian Craton. Anomalously high velocities (8.4–8.5 km/s) were modeled in some blocks of the craton. Two zones of velocity inversion were discovered at depths of 100 and 150 km. But the asthenosphere as a low velocity zone at depth of 250–300 km has not been recognized in the velocity cross-section. Several reflection boundaries were distinguished within the upper mantle at depths of around 100, 150, 250 and 350 km. They show increasing the upper mantle velocities in the craton centre and their decreasing in the southern part of the craton. Three horizontal boundaries characterize the structure of the transition zone between the upper and lower mantle. Their depths are 410, 500 and 680 km.
Keywords: supper-long seismic profiles, upper mantle, asthenosphere.
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