The Vyatka deformations in the East European Platform: Formation dynamics and expression in recent structure

Abstract

The Vyatka intracratonic deformations were formed under WNW-ESE compressive stress created by the presence of the Klimkovo-Nema basement high situated to the east. The compression settings at depth were released at the surface as strike-slip stress regime, which is imprinted in the macrostructural pattern and mesostructural assemblies. Compression was transformed upward into extension with partial retention of the transverse (relative to the deformations) axis of relative shortening. These structural and dynamic features along with the relatively early origination of deformations in the Oligocene make it possible to connect them with the impact of the recent Urals, which arose at the same time and were deformed in the same manner. Inasmuch as the Urals, in the opinion of some researchers, belongs to the Peri-Indian collision region, the Vyatka deformations may presumably be regarded as the extreme northwestern element of this region. The deformations are continuing to develop up to now, but at least during the Pliocene and Quaternary they developed jointly with another group of recent structural elements extending in the latitudinalnortheastern direction as a system of nearly parallel gentle meganticlines and megasynlines with a great radius of curvature. The megasynclines are expressed especially distinctly, making up a structural framework. The possible interpretation of the recent latitudinal structural elements is discussed in the paper. They are most probably linked to the near-meridional extension under the westward stress from the Urals. The interaction of variously oriented recent structural elements was a cause of dissimilar expression of the Vyatka deformations in the topography. They rise at the intersections with the near-latitudinal ranges and are overlapped by Quaternary cover near the near-latitudinal basins.