Recent and paleo-stresses at the northern margin of the Black Sea and the Crimea Mountain in Meso-Cenozoic—Quarter (according to mechanisms of earthquakes foci and field tectonophysical data)

Abstract

Recent stress fields at the northern margin of the Black Sea have been characterized on the base of 32 mechanisms of the earthquakes foci. Orientations of compression axes in the foci give evidence that present-day tectonic process takes place under conditions of compression and transpression. For 13 mechanisms located within the band between the southern cost of the Crimea and the base of the continental slope regional stress field has been estimated, which reflects deformational regime of horizontal stress in northwest—southeast direction. The results of specification of paleostresses fields and deformation regimes have been presented according to field tectonophysical observations in 105 sites. Interpretation has been fulfilled within the limits of two generalized stages: extension in the Early Cretaceous and compression in the Cenozoic—Quarter. Stress fields of inverse, nappe and strike-slip types have been attributed to the stage of Cenozoic compression. Generalized paths of compression have been plotted, which form fan-like pattern within the arc-like sector of the South Coast of the Crimea from cape Meganom to cape Ayu-Dag and change their direction from north—east to west—east. Averaged stress fields have been calculated, which are of inverse type in Sudak-Feodosian zone and are represented by strike-slip types for the central and western parts of the Mountain Crimea (MC). The southwestern part of the MC is characterized by strike-slip-type stress field with northwest—northeast direction of the compression axis. The stage of Cretaceous extension is characterized by stress fields of normal type. The southwestern part of MC is characterized by north-north-east—north-north-west trend of extension and for the central part of MC the north-east—south-west direction of extension has been obtained.