NEOTECTONICS OF THE VORONTSOVSKAYAZONE AND THE PROBLEM OF YOUNG THRUSTS IN THE WESTERN CAUCASUSS

A. Nesmeyanov¹, O. A. Voeykova^1,*

¹Sergeev Institute of Environmental Geoscience RAS (IEG RAS) Ulansky per. 13, bld. 2, Moscow, 101000
*E-mail: vvoa49@mail.ru

On the southern slope of the Greater Caucasus, the youngest thrusts are usually distinguished within the Vorontsovskaya zone. Here, the Cretaceous and Eocene deposits of the thrust allochtons overlap the Oligocene molasses of the Adler Basin. Traditionally, Alpine (Meso-Cenozoic) structures were singled out as the youngestones. Structural adjustment at the beginning of thenewest stage and before its late orogenic stage was not taken into account. Detailed neotectonic studies using the orotectonic method allowed us to distinguish between thestructures of different age. The Late Orogenic Vorontsovskayazone was revealed, including its frontal visor thrusts, axial horst and rear graben. This set of structures is typical for suture-block zones. Such zones are known in epiplatform and island arc orogens (Tien Shan, Sakhalin). Their formation usually includes four stages of development. These stages are highlighted and dated in the Vorontsovskayazone. Gentle thrusts with displacement amplitudes of tens of kilometers were formed in it at the pre-neotectonic and early-orogenic stages. At the late-orogenic stage, a change in the tectodynamic situation led to the intensification of visor thrusts with displacement amplitudes of the first kilometers and the formation of the Vorontsov suture-block zone. This zone is located on the southern side of the neotectonic megavault of the Western Caucasus. It localizes the main part of the young (Pliocene-Quaternary) thrusts.

Key words: Greater Caucasus, fault, thrusts, horst, graben, neotectonics, depression, deflection, Vorontsoskaya suture-block zone, orotectonic method

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