COMMENTS ON «THE OPEN LETTER TO THE MEMBERS OF THE BUREAU OF THE NATIONAL STRATIGRAPHIC COMMITTEE OF UKRAINE AND FELLOW PRECAMBRIAN GEOLOGISTS» V.P. KYRYLYUK

• Дата: 2017
• Автор: Stepanjuk, L.M.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: Institute of Geological Sciences, NAS of Ukraine 2017
• Теми: Ukrainian Shield; stratigraphic scheme; geological time scale; Archean; Proterozoic; granulitic association; Украинский щит; стратиграфческая схема; шкала геологического времени; архей; протерозой; гранулитовая ассоциация; Український щит; стратиграфічна схема; шкала геологічного часу; грану- літова асоціація; 551.7.03/74(477)
• Онлайн доступ: http://geojournal.igs-nas.org.ua/article/view/122812
• Назва журналу: Geological journal

V.P. Kyrylyuk proposals as to stratigraphic subdivision of early Precambrian formations of Ukrainian Shield as a whole and rock association of Dniester-Bug megablock in particular are analysed. On an example of supercrustal formations of Dniester-Bug megablock it is shown, that among rocks of granulitic association, in addition to that stratogenic formations (primarily sedimentary, volcanogenic, chemogenic, and others) there are more late (intrusive-magmatic, metasomatic) rocks which formation is caused by the superimposed endogenic activity. The morphology of these units, their relations with other supercrustal rocks and occurrence modes are formed as a the result of the same superimposed endogenic activity. Simple assumption of these formations to be the treated as suites will lead only to increase in volumes of these stratigraphic units and the interpreation of contacts of their vein (intrusive magmatic and metasomatic) varieties as primary stratification can cause wrong interpretation of tectonic structure of the territory. Plutonic (metamorphosed dikes of diabases) and metasomatic (biotite, a garnet-biotite gneisses, granulites and eulysite) formations are also found in rhythmical-layered alumina-basic formations. If these rocks be excluded from geological section, remained petroparagenesis will include hyperstene, bi-pyroxene plagiogneisses and crystalloshists, that is typical of Tyvrivka strata (enderbite-gneiss formation). Leucocratic biotite and garnet-biotite gneisses that comprize about 80 % of high-alumina-quartzitic formation volume (Kosharo-Oleksandrivka suite) are also metasomatic in origin.