Erosional history of Preolkhon region

The tectonic basis of Preolkhon Region relief is the Olkhon Terrain, which formation begun in the early Paleozoic and included two stages: 1) a subduction of “arc-terrain» type (cover and dome paragenesis), 2) a collision of “terrain-continent” type (strike-slip paragenesis). During the Mesozoic collision contacts of the Siberian Plate and mountains bordering its southern part led to a relaxation of the squeezing tension along the strike-slip lithons of the Olkhon Terrain, and it got the prolate form. The rift stage is associated with a renewal of strike-slip motions on Primorsky and Priolkhonsky Faults. Olkhon Terrain was reduced, but in the base it remained stable and got a position between downgoing Central Baikal Basin and growing Primorsky Range. Inside the terrain, in the conditions of cross shift small pull-apart structures were developed, where faults were formed along the feathering gaps. In the Late Pleistocene-Holocene stage Primorsky Range, Small Sea Depression and Priolkhon Plateau had been formed. From a perspective of morphological structure Preolkhon Region retained the features of an independent block (the Olkhon Terrain) since a Caledonian tectogenesis.