Geophysical processes and biosphere: article

Аnnotation: For the last 150 years within the framework of geosynclinal and then plate-tectonic concepts, the formation of fold-thrust dislocations of layered rocks in the Earth's crust is considered as a consequence of lateral compression of such rocks by converging platforms or lithospheric plates. Such convergences were reliably confirmed by modern geodetic measurements. At the same time there are less popular notions, according to which these dislocations are formed as a result of certain local, autonomous processes. The essence of the problem is that the unambiguously established overwhelming prevalence of ordered horizontal compression over the vertical lithostatic pressure in the Earth’s crust, both according to the focal mechanisms of earthquake and stress measurements in situ in mine workings, makes it necessary to give preference to the global mechanism of compression in the form of convergence of horizontally moving lithospheric plates. This convergence is reliably established on a global scale by modern high-precision geodetic GPS measurements. However, similar GPS measurements, but not on global, yet on regional or local networks in number of cases gave the opposite result. They did not reveal a decrease, but an increase in the width of representative parts of the mountain belts. A detailed study of the geological structure of such areas has shown that the main role in its formation is played by scaly thrusts, sometimes turning into small tectonic covers, and associated with these dislocations, subordinate to them linear folds and groups of such folds. The formation of such a cover-thrust tectonic structure continues at the present time. For a number of years, the authors have developed a hypothesis according to which these fold-thrust dislocations in the Earth's crust are formed as a result of an increase in the volume of layered rocks. They are expressed as stresses of volume expansion, «outward pressure», similar to the stresses of external compression. One of the results of this volume expansion should be an increase in the area occupied by these stratified rocks. They cease to fit in the territory that they occupied before. As a result, layered rocks are crushed into folds, dissected by thrusts, and tend to overcover adjacent territories. It is assumed that the outward pressure, increase in the volume, width and area of layered rocks are the result of the introduction of additional mineral material into them by ascending streams of deep mineralized fluids. The increase in the volume and the width of the mountain structure during the formation of its tectonic structure is indirectly confirmed in a number of regions by the near-vertical formations in the Earth's crust observed by geophysical methods. These formations have different velocity characteristics compared to the enclosing environment. They can be interpreted as channels of permeability for the entry of deep fluids. All this gives us reason to believe that the process of autonomous folding and thrusting in the crust actually exists at the regional level, first of all within the mobile belts, along with the global playtectonic mechanism.