Structural relationships of Cenozoic folding deformations and salt movements of the Chervonooskil dome

Abstract

Statement of the general problem. Folding develops during collisional epochs lasting in the first millions of years. The growth of salt diapirs takes place over tens to hundreds of millions of years. The problem is to establish the structural consequences of the interaction of these different tectonic movements.

Analysis of previous studies and publications. Folding and salt diapirs are manifested on the northwestern outskirts of Donbass. Detailed geological maps have been compiled for the territory, faults have been established and traced, and tectonites of the Saalian, Laramian, and Attic phases of folding have been identified.

Unsolved part of the general problem. In the area of the Chervonooskil dome, folded deformations of Laramian and Attic age, as well as deformations from the growth of a salt diapir, have been established. The structural relationships between these different tectonic processes are unresolved.

The purpose of the article is to establish the structural results of folded and salt dome movements in the vicinity of the Chervonooskil dome.

The research method is structural geology. The geological space is divided into tectonic blocks. The volumes of the blocks are divided into structural floors by angular unconformities. The three-dimensional shapes of the surfaces of angular unconformities are depicted by isolines. The shapes of the folds of different structural floors were analyzed.

Main results of the study. Laramie folding of the territory is manifested in post-Cretaceous - pre-Eocene discontinuous disturbances, linear folds with a length of more than 100 km, angular unconformity in the sole of the Cenozoic structural floor. Attic deformations are manifested in post-Miocene - pre-Pliocene discontinuous disturbances, erosion of Eocene-Miocene deposits, in the angular unconformity between the Miocene and Pliocene. Laramie folds are secondarily dislocated and broken into blocks.

In the Mesozoic structural floor, the Chervonooskil salt dome is manifested by a brachianticline, a bend of the axes of adjacent Laramie folds, as well as a compensatory surrounding depression with an amplitude of 300 m. The sole of the Cenozoic in the compensatory depression is dipped by 40 - 80 m. The axes of subsidence in the Cenozoic and Mesozoic floors coincide. Halokinetic forms are deformed by Attic and Laramian thrusts.

Scientific novelty. On the basis of quantitative structural data for the Chervonooskil dome, it is shown that the cross-thrust folded structure of the northwestern outskirts of Donbass is complicated not only by the rise of the salt stock, but also by the formation of compensatory depressions. Compensatory depression is reflected in the structure of the Laramie folded complex with a larger amplitude than in the structure of the Attic complex.

Conclusions. The increase in the amplitude of depression in Mesozoic sediments relative to Cenozoic sediments indicates the inherited development of halokinesis throughout the Cenozoic and the accumulation of amplitudes of depression of different ages.