Paleogeothermal and paleotectonic reconstructions based on vitrinite thermometry data (on the example of the upper paleozoic deposits of the Dnieper-Donets depression and adjacent areas of Donbass)

The article is devoted to paleogeothermal and paleotectonic reconstructions based on the results of processing the vitrinite reflectance data array of coal organic matter of the Upper Paleozoic sediments from the Don-Dnieper Downwarp (within the Dnieper-Donets Depression and adjacent areas of Donbass). It was found that paleogeothermal parameters changed under the influence of geotectonic, magmatic and lithofacies formation conditions of the Upper Paleozoic deposits. Analysis of changes and regularities distribution of paleogeothermal characteristics made it possible to assess the evolution of the thermal field, changes in the tectonic movements character, to identify the role of volcanism, deep faults geodynamics, lithosphere thickness in the thermal history of the region under study. It is shown that with the help of paleostructural analysis, based on data on the thermal maturity degree of coal organic matter, it is possible to judge the activity changes of tectonic structures in time, the formation sequence, to establish the amplitudes of their mutual displacement and rank according to oil and gas potential. Based on the results of the work, maps of the paleogeothermal gradients distribution and the amplitudes of rock masses vertical displacements were constructed. The presented maps should be considered as a universal information material that can be used to determine the features of the regional distribution of the above parameters, as well as become an important tool in the study of tectonic and thermal history, identification changes trends and distribution patterns of paleo­geothermal characteristics.

Paleomagnetism of the Kola Peninsula's dykes, NE Fennoscandia: the review

<p>In this work we present the overview of comprehensive research on paleomagnetism and rock magnetism of more than 120 Paleoproterozoic and Neoarchean dykes from the Kola Peninsula, NE Fennoscandia. We discuss our results in a context of Precambrian paleotectonic reconstructions of Fennoscandia and Murmansk craton in particular for the time intervals corresponding to the dyke magmatism. We also show our progress in dating of the remanent magnetization components using some approaches of isotope geochronology, such as U-Pb dating of baddeleyite and Ar/Ar dating of mica, feldspar and amphibole. In total, we have been able to calculate virtual geomagnetic poles for the selected dykes and to make some conclusions about paleotectonics of the Murmansk craton at the corresponding time. New paleointensity data for some 2.50 and 2.68 Ga dykes will be also presented and commented. The study is supported by the grant of RSF #16-17-10260.</p>

Geodynamics of carbonatites from the paleoreconstraction

Carbonatite are of a great economic importance because this rocks contain valuable rare metals. At present tree models of geodynamic regime of carbonatites formation are actively develop. 1- the generation of carbonatite melts within the lithospheric mantle, 2- the close connection of carbonatites with the zones of orogenesis, 3- a large group of carbonatites links to deepseated mantle plumes. For the first time using the modern model of “absolute” paleotectonic reconstructions and large database was showed the general connection of Phanerozoic carbonatites to the large areas of low velocities of S‑waves located in the lower mantle — zones of the generation of deep mantle plumes.

Pop-up structures of Petrodonetska anticline and adjacent territories

Presents the results concerning a comparative analysis of paleotectonic reconstructions of the tectonic conditions dynamics for the formation of local plicative deformations and faulting in the study of the macrostructure and its local separation using the example of the Almazno-Marievskyi region. The formation conditions characteristics of the Petrodonetska anticline and adjacent territories were obtained. In the plan, they are located en echelon-like, which is associated with a shift. The structure of the latter indicates a thrusting of the sedimentary stratum layers from the center of the Donetsk trough to its northern periphery. The analysis of reconstruction results regarding the formation of the Lysychanska anticline on the border with the Severodonetskyi thrust and sections in experimental research of pop-up structures, reveals their similarity in structure and formation. With oblique convergence of blocks from the shear zone, a series of overlapping thrusts are extruded. A central graben arises within the transpressive shear zone, along its axis due to the divergent reverse faults in the arched uplift. A system of parallel thrust faults forms a ramp. The necessity of using the system modeling method (the finite element method), which improves the methods for predicting gas-containing tectonic elements in the pop-up structures, is justified.