Mechanisms and stages of structure formation in the process of progressive deformations (Uakit zone, Baikal fold region)

Mechanisms and stages of structure formation in the course of progressive deformations are discussed using the structural evolution of the Mukhtunnyj Sequence in the Uakit zone as an example. It is concluded that the Mukhtunnyi Sequence was formed as a result of two deformation stages. During the first stage, a superposed structural paragenesis, which displays several phases of deformation, was formed. The variations in the trends of fold structures can be explained by the rotation of large thrust slices during the late deformation phases. The structures and structural parageneses of the second stage are local and experienced the thermal and mechanical effects of emplacement of Late Paleozoic intrusive massifs. It has been demonstrated that the structures of various trends were not produced by the superposition of compression deformations at various stages but reflect the consecutive formation of structural parageneses during various phases of the same stage. The effect of the rather shallow basement determined the specific features of the structural evolution of the sequence. The proposed model can be viewed as a possible formation mechanism for strongly deformed mosaic-block segments in the inner parts of the Baikal fold region.