Denudation scarps as indicators of regional tectonic stresses

Abstract

The present-day denudation scarps on the Russian Plain, many hundred kilometers in extent, resemble faults. The kinematics of low-amplitude displacements deduced from their configuration and mesotectonic measurements corresponds to the recent regional stress regime transmitted in the lateral direction to the platform basement via consolidated crust from the zone of Alpine collision. At the same time, no high-amplitude regional faults are known near the scarps. This paradox can be resolved assuming that the scarps are formed by tightening of low-amplitude stress-release joints rather than along extended faults. The zones of such joints mark the belts of stresses in the platform basement induced by collision. Since the erosion that forms a scarp relaxes residual tectonic stresses, a river’s bank is not destroyed chaotically, so that particular segments of scarp follow paths of the regional stress field. Thus, the configuration of banks, in combination with other structural features, makes its possible to forecast the character of recent collision-related stresses transmitted from a depth.