EVALUATION OF STRESS-STRAIN STATE OF LITHOSPHERE IN RECTANGULAR AND CYLINDRICAL MODELS ALONG THE CRATON PROFILE

The problem of an inhomogeneous distribution influence of properties and geometry on the stress-strain state of a 500 km thick block model under the influence of gravity within the framework of the medium behavior of an elastic-plastic model is considered. The calculations were carried out in a 2D formulation of a plain strain state for a rectangular and cylindrical profile, taking into account the curvature of the Earth’s surface. It is shown that anomalies of the stress-strain state and zones of irreversible deformation development are determined primarily by the heterogeneous nature of the structure, the presence of density and rheological anomalies. The geometry of the models significantly affects primarily the stress state in the crust, taking into account the curvature of the lithosphere where the greatest shear strength determines the development of irreversible deformation depending on the heterogeneity of the environment. In this work, numerical modeling was carried out to assess the influence of the geometric factor on the stress-strain state of the lithosphere. The initial geometry of the medium was constructed on the basis of a seismic model along the Craton profile in rectangular and cylindrical coordinates with a length of 3600 km and a depth of 500 km. A comparison of the obtained solutions was carried out. The change in the stress-strain state during the lifting and immersion of a medium block in a cylindrical problem formulation is considered. It is shown that vertical displacements in such a formulation have a noticeable effect on horizontal stresses and can lead to the development of irreversible deformation. It has been established that the deviation of shear stresses from horizontal ones at the daytime surface is negligible in the case of a cylindrical formulation of the problem with successive layer-by-layer build-up of the crust. The maximum deviation is achieved in the middle part of the deformed layer.