The dissertation for а doctor of Geological science degree in speciality 04.00.01 «General and regional geology». – M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of NAS of Ukraine, Institute of Geological Sciences of the National Academy of Sciences of Ukraine, Kiev, 2020.
It was established that in all megabloks and suture zones of Ukrainian Shield (USh), tectonic rearrangements were manifested similarly: in several stages of structural-material transformations of a crystalline base when the direction of the paleo-strain was changed and mainly by a regressive change in the pressure-temperature conditions of these alterations. Namely, in all megablocks of the USh there is a change in the structural plans from the north-eastern strike, through the meridional, north-west to the repeated submeridional and north-eastern. The dislocation transformations for the first three structural plans corresponded to the P-T conditions from granulite to amphibolite of metamorphic facies; they were formed by geological bodies with age > 3.2, 3.2 and 2.8 billion years. Dislocation transformations in the formation of repeated submeridional and north-eastern structural plans corresponded to the conditions from amphibolite to green-schist facies of metamorphism; they are formed by geological bodies with age of 2.0 and 1.8 billion years. Younger tectonic deformations occurred in cold conditions and did not significantly change the structure of the USh formed in the Paleoproterozoic.
A similar manifestation of structural plans changes for all megablocks USh shows that at the appropriate stages of tectonic reorganization all megablocks had common conditions tectogenesis and the formation of structural patterns in them occurred under the influence of general, probably global, tectonic stresses.
Each of the above-mentioned tectonic impulses provoked the formation of new rock bodies, the interaction of which a cross (hybrid) structural pattern of the USh created. The structural and material transformations of the fourth of the selected stages (~ 2.0 billion years ago) were revealed most total, with the formation of essentially shear dislocation systems. This is the Priazov dislocation system (Priazovsky megablock of USh and OPsZ), Prydnipro (Middle-Prydniprovsky megablock and adjacent suture zones), Ingulska (Ingul megablock and adjoining suture zones), and others. These systems are formed by geological bodies of several higher levels and generations. At each of the levels (from the macro-to-micro level of the object's organization), these bodies reproduce synshear structural patterns.
The edges of the megablocks (relatively central), as a result of essentially shearing transformations, are more intensively structurally and materially are transformed and, together with the suture zones, are classified as linear components of the shear systems. The central parts of the megablocks USh are relatively weakly altered fragments of the foundation, which were, to varying degrees, survived from early Proterozoic linearizations and were formed due to the separation under the action of shear stresses, accompanied by the scroll of their individual segments. They have features of the median and vortex massifs and are classified as sub-ring (ovaloid) constituent of shear systems (the axial part of the Ingul megablock, the central part of the West-Priazov block, and others).
It is substantiated that characterized U- or U-Th- perspective objects are self-similar, highly ordered dislocation structures and take on the fixed structural positions in the Paleoproterozoic structural pattern of the USh. In addition, it has been shown that U, Th-ore and host body have similar morphologies, elements of occurrence, the number of mineral generations and small structural forms; also – the number of useful components (in particular, U, Th) of ore bodies is regularly increasing from the Paleoarchaean to the Paleoproterozoic, while the opposite is the case in the containing rocks.
All this indicates that U, Th-ore bodies were formed due to the same multi-stages structural and material transformations as contained geological bodies. In this case, the structural-material transformations were not superimposed on the existing fold form, but they occurred simultaneously in several stages throughout the volume of the foundation with the formation of fold-like ore-perspective objects. Therefore, ore-promising bodies are occupied fixed structural cells in the Paleoproterozoic structural pattern, which mark the different-rank shadow pressure. These are T, S, Ө and δ are structural positions. Such an concrete locate is defined as the leading search criterion. The forecast of the location of new similar objects is given.
Key words: dislocation system, shear, generation of structures, ore bodies, structural positions.
