Planation surf ace of the Ukrainian shield basement, its origin and age

Abstract

The planation surface of the Ukrainian shield basement was formed at Aalenian (Middle Yurassic) time by processes of continental denudation under the conditions of mainly humid climate. Later on differentiated movements of the basement's blocks resulted in division of the planation surface into areas differing in altitudes. The primary Aalenian surface conserved its topography only under mantle of Middle Yurassic sediments; at other places it has been transformed by younger erosion and its age can be determined after sedimentary rocks overlying the basement.

Nevertheless, general topography of the primary surface of the basement (position of main divides and river valleys) has been conserved until now.