Evidence of Early Paleoproterozoic (2.4–2.1 Ga) magmatic events in the south of the Siberian Craton

The authors’ new findings and previously published data on the geological history of the terranes that formed the Siberian Craton in the Paleoproterozoic were analyzed. It is shown that the 2.4–2.1 Ga interval, which was previously considered practically amagmatic, contains locally manifested evidence of magmatic activity in some disjoint terranes, which were later, during the assembly of the Siberian Craton, structurally integrated into its orogenic belts. The indicators of these events, which occurred at the analyzed stage in the evolution of the terranes that formed the Siberian Craton, are both rare igneous rocks aged 2.25–2.10 Ga, and Paleoproterozoic metamorphosed terrigenous rocks containing detrital zircons aged 2.4–2.1 Ga. Since the predominant rocks of almost all orogenic belts of the Siberian Craton are igneous rocks of 2.00–1.85 Ga age, formed both at the orogeny stage and during post-collisional extension, it is these huge magmatic complexes in Mesoproterozoic and Neoproterozoic sedimentary strata that provide the bulk of clastic zircons, almost completely obscuring the contribution of magmatic rocks of 2.4–2.1 Ga age. However, these poorly manifested events did occur in the geological history of Siberia. Thus, considering the new data on the magmatic and meta-sedimentary complexes of the Siberian Craton, it is safe to assume that endogenous processes in the terranes comprised within its structure were not at full stop (in a gap) in the 2.4–2.1 Ga time interval, as it was previously believed for most ancient cratons, but there was a significant tectono-magmatic lull (TML) with local-scale magmatic events.