Tectonic History and a New Evolution Model of the Mid-Russian Aulacogen

摘要

As follows from multidisciplinary analysis of the present-day structure of the Mid-Russian Aulacogen, its formation was related to large-scale crustal delamination (simple shear). The proposed theoretical model implies that the aulacogen evolved from a particular shear to a shear zone with development by the Late Riphean of a triad of paragenetically associated structural features, including a central anticlinal uplift and its adjoining compensation troughs. The uplift was accompanied by the lateral progradation and shallowing of the troughs in compliance with the elastic-wave propagation mechanism, leading to a decrease in the wave amplitude at a finite surface area with an increase in the wavelength. The difference in extension of the opposite flanks of the aulacogen accounts for its wedged shape and the southwestward degradation of the structural triad. As a whole, the tectonic prehistory and evolution of the Mid-Russian Aulacogen were guided by relative displacements of rigid Archean massifs beneath the Russian Platform.