| Lidiya A. Sim | Ph.D., deputy general director for development | IFZ RAN, Moscow sim@ifz.ru |
| Ilnur A. Sabirov | assistant of the department of lithology | Gubkin University, Moscow Sabirov.i@gubkin.ru |
| Nikita A. Gordeev | Ph.D. student | IFZ RAN, Moscow gord@ifz.ru |
The purpose of the research in this paper was to draw up a newest geodynamic scheme for the Western part of the Turan plate based on the recovery of neotectonic stresses and to determine local stretching areas at the intersection of multidirectional shifts. Tectonic stresses are caused by the influence of the Kopet-Dag and Caucasus orogeny. The compression axis is oriented submeridionally, and the extension axis is sub-latitude. This ensured the maximum activity of the diagonal strike-slip faults along which tectonic stresses were restored. At the intersection of oppositely directed strike-slip faults, local stretching areas are distinguished, which are characterized by higher permeability. The concentration of hydrocarbon deposits is calculated over a grid of 20x20 km2; it turned out to be increased in the stretching sectors. High permeability of rocks in the stretching sectors is of fundamental importance for the prediction of areas of hydrocarbon concentration.
Materials and methods
The neotectonic faults are recognized using topographic maps and space images of Mangyshlak. Most of them is confirmed by published gravity data. Along the faults, the orientation of the compression and extension axes was restored by the author’s structural-geomorphological method for the reconstruction of shear tectonic stresses and the directions of strike-slip faults was determined. In the areas of intersection of oppositely directed strike-slip faults, local stretching areas are highlighted. According to the tectonic scheme of South Mangyshlak with hydrocarbon deposits, the density of deposits was calculated.
Results
A scheme of the geodynamics of Mangyshlak is drawn up, which shows the kinematic types of the neotectonic faults, the areas of local compression and tension at the intersection of oppositely directed strike-slip faults are determined.The increased number of deposits in the stretching sectors proves the prospect of geodynamic studies in oil and gas bearing areas.
Conclusions
For the first time, a scheme of the latest geodynamics of the west of the Turan plate was compiled. She showed that the deformation of the study area takes place in a shear stress field with a meridional orientation of the compression axis and a latitudinal axis of tension. This orientation of the axes of the main normal stresses is due to the development of the alpine structures of the Caucasus and the Kopet-Dag.
In the stretching sectors at the intersection of oppositely directed strike-slip faults an increased number of hydrocarbon deposits was recorded.
The allocated sectors of stretching under other equal geological conditions provide increased permeability of rocks due to the situation of stretching, so they can be informative:
1. When planning additional exploration work on the underlying horizons in the territory of Mangyshlak.
2. The local stretching sector must be taken into account when solving hydrogeological and ecological problems in order to account for areas with increased water cut and karst formation.
3. The scheme of the latest geodynamics can be used in engineering geological surveys for the initial assessment of the most dangerous faults.
