THE PERMIAN-TRIASSIC TRAPS OCCURRENCES IN WEST SIBERIA

V. S. Bochkarev

Siberian Research and Analytical Centre, Tyumen, Russia

Based on deep well columns, the author has defined that, within the West-Siberian geosyneclise, the Permian-Triassic traps occur as narrow bands with a width not exceeding 60 km. Those are Korotchaevskaya, Svetlogorskaya, and Malokhetskaya volcano-tectonic depressions composed of tuffaceous-basaltic Krasnoselkupskaya Series rocks. Matching these volcanoes with cenotype basalts of the Turinskaya Series is not correct, as the Turinskaya Series is much younger and has a formation different from traps. The volcanotectonic depressions are divided by horsts which are mainly pre-Cambrian in the east and Middle Paleozoic in the west and the central part. Grabens are numerous, with about 100 depressions, and are composed of the Turinskaya Series rocks. According to SG‑6 and SG‑7 wells data, traps contain helium isotopes with a ratio of about 16∙10–8, the Ar-Ar age is 248 mln years to 251 mln years, low-potassium varieties make up to 50 % of the section.

Keywords: West Siberia, traps, Turinskaya Series, volcano-tectonic depressions, deep wells.

DOI 10.20403/2078-0575-2017-4-115-123

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