Home – Home – Jornals – Russian Geology and Geophysics 2005 number 2

Principles of medium-scale neotectonic mapping have been considered by the example of junction of the old Siberian Platform and young West Siberian Plate. Instead of neotectonic systems commonly used as a basic unit in teotectonic mapping, the fault-block structure of terranes and its morphotectonic analysis are proposed. The role of faults in the formation of contrasting relief features increases in the transition from global through regional to local level of structures. Being a derivative of neotectonic movements, the relief mirrors neotectonic structures. The more contrasting relief, the younger it is and the faster neotectonic movements are. A schematic succession of neotectonic analysis is as follows: morphotectonic analysis of relief - detailed mapping of network of fault structures - recognition and ranking of neotectonic blocks - characteristic of neotectonic relief within the blocks and estimation of its contrast - calculation of velocities of neotectonic movements - construction of a neotectonic map.At the junction of the Siberian Platform and West Siberian Plate in the lower reaches of the Kan River, the neotectonic structure is controlled by the Baikal-Yenisei fault zone, represented by a dense network of submeridional reverse-fault-nappe structures having distinct traces of Pleistocene rejuvenation. The zone of the Baikal-Yenisei fault is crossed by young diagonal strike-slip structures, of which the northwestern ones are dextral, and northeastern, sinistral.This system of faults cuts out a series of macro- and microblocks. West of the Baikal-Yenisei fault, the block structures tend to subside, and east of it, they tend to rise. The velocities of subsiding and rising are quite close, which is inferred from the compensated filling of basins with young sediments in the immediate vicinity of the rising block. Vertical and horizontal displacements along young faults have been recognized for the study area, their kinematic type has been ascertained, and the character of lithosphere blocking has been defined as a function of the type of its stress state. It has been established that the territory is most fragmented where fields of compressive and shear stresses are superposed.