EVALUATION OF THE VOLUMES AND GENESIS OF PERMO-TRIASSIC TRAP MAGMATISM ON THE SIBERIAN PLATFOFM

Abstract

Volumes of various trap-magmatic facies have been evaluated by invoking deep-drilling data, geophysical data, field studies, and recent notions of the geodynamic settings of their formation at the Permo-Triassic boundary. The total volume of trap-magmatic rocks is evaluated at 1 752 000 km3 at the present-day denudation level. Diverse facies and trap varieties, as well as their composition, point to a complicated geodynamic setting: for a short period (1-10 Ma) huge volumes of substantially tholeiitic melts were produced, which formed a sequence of lavas, volcanoclastics, and intrusive bodies. This sequence, several kilometers in thickness, constituted up to 70% of the sedimentary cover of the platform. The role of the Siberian superplume in the temporal-spatial succession of formation of the huge volumes of various trap-magmatic facies is considered.