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Abstract

UDC (551.243:551.72):550.83(571.5-12)

GEOLOGICAL-GEOPHYSICAL CONDITIONS FOR SOUTHEASTERN EXTENTION OF THE SIBERIAN PLATFORM

V. S. Staroseltsev

The analysis of a deep geologic-geophysical model of the Earth’s crust and the upper mantle on a 3-DV base geologic-geophysical profile (a northwestern part) allowed raising a question of the eastward extension of the southeastern Siberian Platform. Grounds to change the southeastern boundary of the Siberian Platform was given by a continuous up to 2 050 km extension of Archaean basement plate in the order of 25-30 km total thickness overlapped by a Phanerozoic cover though broken by a system of faults. It is important that a sketch map of geotectonic classification of Sheets R-54, 55 and partially O-55 of a geologic map at a 1:1 000 000 scale published in 1999 shows a 1 500 to 2 100 km interval of the 3-DV profile running along the Verkhoyansk-Kolyma passive margin of the Siberian Continent, in the south of which Archaean rocks of the Okhotsk microcontinent outcrop. The latter is also presented on a geologic map of Sheet R-54 published in 2011. Faulting of the cover and crust in the marginal zones of the Siberian Platform, similar to that indicated by the 3-DV base profile, also manifests itself in other marginal zones of the Siberian Platform, for example, on a 1-SB base profile (Batholith). An organogenic carbonate formation promising for oil and gas is most evident in the 1 500-1 600 km interval of the 3-DV profile.

Key words: Archaean basement, Okhotsk microcontinent, faults, oil-and-gas promising formation, southeastward extension of the Siberian Platform.