Neotectonic structure of Tunkin rift

Abstract

Tunkin rift is the western flank of Baikal rift zone. lt is represented by intermountain depressions and low- mountainous horst ridges between them. Depressions have Pliocene-Quaternary sediment filling rich of volcanic material. Northern boundary of the rift is Tunldn normal fault, which appears on the surface as high bench. The horst ridges are located in the places where this fault changes its direction from N-E to sublatitudinal and conversely.

The socle of Mongol-Siberian belt is characterized by submeridional upheaval in this area. and Tunkin rift is located on the eastern slope of it. The upheaval is the morphological effect of vertical channel in the astenosphere. This position of rift forces the lithosphere blocks to move eastward, which in turn determines the structural features of Tunkin rift and lateral compression in the foci of the eartquakes.