Deep structure of the morphostructures at the eastern part of the region of the Baikalian-Amur main line (based on gravimetric data)

Abstract

The correlation is discussed existing between hypsometric position and special features of the solid rocks composition, Large positive morphostructures (outlined by residual minima of gravity) were proved to consist of rocks characterized by low density (σ=2,57-2,65 g/cm³) and rather high content of the silicon oxide, their chemical composition being close to that of moderately acid rock - granodiorite. Large morphostructural depressions characterized by residual maxima of gravity consist of dense basic rocks (σ=2,75-2,90 g/cm³), their average chemical composition corresponding to diorite. Taking into account the structures of the upper layers of the earthcrust, both kinds of morphostructures can be explained within the frame of the Pratt-Heyford isostatic model. However some «anti-isostatic» morphostructures occasionally occur, which are blocks of dense rocks uplifted to a considerable height and lowered blocks of low density.