L.S. Osmachko. STAGES OF FORMATION OF THE STRUCTURE OF ROS-TIKYCH MEGABLOCK OF UKRAINIAN SHIELD
STAGES OF FORMATION OF THE STRUCTURE OF ROS-TIKYCH MEGABLOCK OF UKRAINIAN SHIELD
L.S. Osmachko, https://orcid.org/0000-0003-1248-261X
SE "Institute of Environmental Geochemistry of the NAS of Ukraine"
34-a, Acad. Palladin Ave., Kyiv, Ukraine, 03142
Mineralogical journal 2019, 41 (3): 54-64
Abstract: The complex analysis of dislocation formations carried out within the Ros-Tikych megablock of Ukrainian Shield (USh) made it possible to establish that tectonic transformations in the western part of USh occurred in several stages. Such transformations took place against the background of rotation of paleostress directions and regressive changes in PT parameters of tectonic transformations. Namely, in the southwestern part of the Ros-Tikych megablock of USh are observed changes in the occurrences of the main components of the structural pattern - from the northeast strike through the meridional, northwest to repeated submeridional and submeridional with vergence to the northeast. Dislocation transformations for the first three structural plans corresponded to РТ conditions ranging from granulite to amphibolite facies of metamorphism; they are formed by geological bodies with the ages of Hf >3.2, 3.2 and 2.8 billion years. Dislocation transformations occurred during the formation of repeated submeridional and submeridional structural plans with vergence to the northeast correspondwith conditions ranging from amphibolite to greenschist facies of metamorphism. They are formed by geological bodies with the ages of 2.0 and 1.8 billion years. More younger tectonic deformations occurred in cold conditions and did not change significantly the structural pattern formed in the Paleoproterozoic. Based on the principle of self-similarity of dislocation structures at all levels of their petro-structural organization, the entire Ros-Tikych megablock is also interpreted as a hybrid dislocation macrostructure formed in the same way as its part studied in detail. Based on the data on the structure of the ore-prospective Volodarsk fold systematizised according to the principle of hierarchy and self-similarity of dislocation formations, it is shown that this object represents highly ordered syn-shear structure and occupies a regular structural position in the Paleoproterozoic structural pattern of this part of USh.
Keywords: Ros-Tikych megablock, generations of structures, syn-shear formations, formation stages.
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