Studies of the Emeishan and Siberian trap provinces have demonstrated abundance of basalt series and giant volumes of lavas and sills (16·106 km3) formed for a very short period of the major step of volcanism. The obtained data permit a model for superplumes with three steps of their formation: early (picrites and alkali basalts), major (tholeiite plateau basalts), and final (ultrabasic and alkaline intrusions). These steps reflect the evolution of a superplume from several independent plumes until the formation of thick lenses of mantle melts at the bottom of the lithosphere and, finally, plumes of differentiated mantle melts. Synchronous syenite-granite intrusions and bimodal volcanic series abundant in the framing of the Siberian traps are the result of melting of the lower crust at depths of 65–70 km under the effect of plume melts. Superplumes promoted the synchronization of events of magmatism and geologic processes repeated at intervals of 30 and 120 Myr. A similar synchronization of global geological events is observed during the activity of superplumes 120, 250 and, possibly, 360 and 480 Ma. During the effusion and intrusion of 8−16·106 km3 of volcanic material for a short interval of 0.6–2 Myr, huge volumes of CO2, SO2, and HF might have been released, capable to destroy the atmospheric system, to disturb the budget of oxygen-free oceanic water, and to lead to the mass extinction of living organisms at the Permian-Triassic boundary.

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