Seismotectonic Deformation of Active Segments of the Junction Zone of the Kolyma–Omolon Superterrane and South Anui Suture (Southeastern Russia)

Geotectonics - Our seismotectonic studies focus on active segments of the junction zone of the Kolyma–Omolon superterrane and the South Anui suture. The aim of our research is to identify...     

Seismotectonic analysis of the Yana-Indigirka segment of the Chersky zone

Kinematic types of seismogenerating structures, morphotectonic features of the present-day topography, and the corresponding tectonic stress fields derived from the focal mechanisms of local earthquake and the types of Late Cenozoic folding and faulting are analyzed to create a model of current geodynamics in the Yana-Indigirka segment of the Chersky seismotectonic zone. The kinematic environment in the Yana-Indigirka segment of the Chersky seismotectonic zone is a result of the interaction of conjugate differently oriented strike-slip displacements under transpression conditions (a compression with strike-slip). It is possible to reconstruct these conditions, if we assume that the Kolyma-Omolon block (superterrain) located in the frontal part of the North American Plate played the role of an active indenter during the approach of the North American and Eurasian Plates.     

Dynamics of seismogenerating structures in the frontal zone of the Kolyma–Omolon superterrane

To develop a model for the dynamics of seismogenerating structures in the frontal zone of the Kolyma–Omolon superterrane (Chersky seismotectonic zone), the following aspects are analyzed: structural–tectonic position, deep structure parameters, active faults, and fields of tectonic stresses as revealed from solutions of focal mechanisms of strong earthquakes and kinematic types of Late Cenozoic fold deformations and faults. It is found that a certain dynamic setting under transpressional conditions takes place and it was caused by the interaction between structures of the Eurasian, North American, and Okhotsk lithospheric plates within regional segments of the Chersky zone (Yana–Indigirka and Indigirka–Kolyma). These conditions are possible if the Kolyma–Omolon block located in the frontal zone of the North American Plate was an indenter. Due to this, some terranes of different geodynamic origin underwent horizontal shortening, under which particular blocks of segments were pushed out laterally along the orogenic belt, on a system of conjugated strike-slip faults of different directions and hierarchical series, in the northwest and southeast directions, respectively, to form the main seismogenerating reverse-fault and thrust structures with the maximum seismic potential (M ≥ 6.5).