PERMO-TRIASSIC TRAP MAGMATISM ON THE SIBERIAN PLATFORM: SOME PROBLEMS OF AGE AND MAXIMUM INTENSITY

Abstract

Using the available literature data and his own K-Ar datings, the author estimates the general duration of the platform magmatism of basic rocks on the Siberian Platform, including the trap magmatism. Its repeated occurrence is confirmed in a wide range from Late Proterozoic to Late Mesozoic. The bulk of the Siberian traps are, however, of certainly Late Paleozoic - Early Mesozoic age. Upon plotting histograms of K-Ar datings with various subdivision classes, a probable activity duration (few tens of Ma) was estimated for four large regions of the platform as well as the maximum total duration. The maximum activity of trap magmatism of lavas, tuffs, and subvolcanic intrusions approaches the Permian-Triassic boundary. According to new Ar-Ar datings, the minimum duration of activity is about 1-3 Ma for the Siberian traps. The maximum and minimum estimates of the Permo-Triassic magmatism duration suggest one or more volcanic catastrophes, though the minimum duration estimate remains to be confirmed additionally.