Faults of the Pre-Baikal submontane trough (Siberian Platform): Structural-genetic analysis

Abstract

Research subject. The pre-Baikal submontane trough is located in the eastern part of the Irkutsk Amphitheater of the Siberian Platform, stretching for 600 km in a north-easterly direction. The trough started to form in the Mesozoic on the Paleozoic folded base and continued in the Cenozoic. The trough is characterized by a complex structure of shafts and deflections complicated by ruptures.Aim. To investigate the insufficiently studied ruptures of the platform cover, which are difficult to map due to minor displacements of their wings.Materials and methods. The method of specialized mapping of crustal fault zones based on a analysis genetically related of ruptures families was used. A network of 18 points of geological and structural observations in rocks of different ages of the sedimentary cover was created.Results. A rank structural-genetic analysis of fractures mapped in rocks of different ages and composition revealed specific features associated with the gradual development of the trough. The ruptures identified in the rocks of the pre-Cenozoic cover of the platform satisfy the parageneses of the compression zone, the dextral strike-slip zone and the extension zone of the north-eastern strike. Deformations in Cenozoic sediments belong to the parageneses of dextral strike-slip zone and the extension zone. These parageneses consist of strike-slip and normal faults.Conclusions. The Cenozoic Pre-Baikal submontane trough was formed under strike-slip and extension conditions. The compression stage is highlighted in the Pre-Cenozoic base.