Horizontally displaced of geomasses in the continental rift structures (on the example of the Dnipro-Donetsk paleorift). Part 1. Structural manifestations of tectonic flows in basement

Abstract

Introduction. At the inversion stages of continental geostructures evolution, the rocks of the basement acquire significant internal volumetric tectonic mobility due to structural and material transformations and deformations of the tectonic flow. The mechanism and scope of structural changes depend on the characteristics of their primary tectonic structure and geodynamics, the intensity of stress-metamorphic deformations of rocks, the nature and number of inversions of tectonic stress fields.

Review of previous publications and studies. Secondary dislocations are important for consideration in geotectonic studies of ancient intra-plate rifts, which include the Dnieper-Donets paleorift (DDP). Studying the systemic organization of its disjunctive tectonics, on the basis of a geometric, kinematic and genetic analysis of structural patterns of faults, it was shown that the rift fault-block structure of the Precambrian basement complicates different-age dislocations of the inversion evolutionary stages.

Purpose and objectives of research. The article is the first of a trilogy that continues research into the dynamic geotectonics of paleorift, highlighting the kinematic mechanisms and the geological consequences of the horizontal movements of geomass. It is devoted to the geotectonic study of structural complications of the collisional stages of tectogeneses in the architecture of the Precambrian foundation.

Materials and methods of research. The original comprehensive method of regional geotectonic studies is to integrate structural-paragenetic and structure-ne-kinematic methods of tectonophysical research of fault systems. On the cartographic material, with the use of the determinants of kinematic indicators and the principle model of coupled deformation parageneses of the tectonic flow, they were detected at the base of the surface with identification in the local anomalies of geophysical fields and amplitudes of the newest (Holocene) vertical tectonic movements.

Presentation of the main material. Territorial distribution and tectonic position of the secondary deformation structures of the tectonic flow of the sub-regional and zonal scales, ranging in the size from first to tens of kilometers complicated by its rift fault-block relief, is studied. They were the result of the deformation mechanism of volumetric tectonic flow of magmatic and metamorphic rocks.

Findings. The morphogenetic types, tectonic position and kinematic mechanisms of secondary deformational structures formation of the tectonic flow which complicates its rift’s fault-block pattern, have been studied. Their reflections in the local anomalies of the magnetic and gravitational potential geophysical fields and in the vertical amplitudes of the newest (Holocene) tectonic movements have been analyzed. Their structure-forming role at the collision stage of the continental crust of DDP evolution is shown.