UPPER MANTLE ROOTS OF SIBERIAN CRATON BASEMENT STRUCTURES ALONG THE RIFT DSS PROFILE
V.D. Suvorov, Z.R. Mishen'kina, and E.A. Mel'nik
A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, prosp. Akad. Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Peaceful nuclear explosions, upper mantle, Siberian craton, Rift DSS profile
Pages: 885-897
Abstract
We investigate the upper mantle velocity structure through processing first arrival data fr om peaceful nuclear explosions. The reported 2D model has been obtained by ray tracing for a spherical Earth, unlike the classical plane-approximation approach with subsequent spherical symmetry corrections, which is not always applicable to a laterally heterogeneous subsurface. The upper mantle velocity highs and lows imaged to 200-220 km depths show obvious correlation with major structures of the craton basement. Namely, low-velocity zones are observed beneath basins, the largest (to 8.0-8.1 km/s) under the Vendian-Cambrian Sayan-Yenisei syneclise. A discontinuous high-velocity layer (8.6-8.7 km/s) at depths between 150 and 240 km is underlain by a zone of lower velocity (8.50-8.55 km/s) down to the 410 km discontinuity, wh ere the velocity at the top of the transition zone is 9.4-9.5 km/s.
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