Three-dimensional Earth’s crust density model of the central part of the Golovanevsk suture zone of the Ukrainian Shield

• Дата: 2018
• Автори: Starostenko, V. I., Kuprienko, P. Ya., Makarenko, I. B., Savchenko, A. S., Legostaeva, O. V.
• Формат: Стаття
• Мова: rus
• Опубліковано: Subbotin Institute of Geophysics of the NAS of Ukraine 2018
• Теми: the Golovanevsk suture zone; density; Earth’s crust; structures with an abnormally high density on the surface of the basement
• Онлайн доступ: https://journals.uran.ua/geofizicheskiy/article/view/137172
• Назва журналу: Geofizicheskiy Zhurnal

Three-dimensional Earth’s crust density model of the central part of the Golovanevsk suture zone of the Ukrainian Shield at the scale 1:50 000 has been given. Model calculations were carried out using automated complex GMT-Auto. The model takes into account the change in density both laterally in accordance with petrophysical data; and with depth in accordance with seismometry data. In this case; an abrupt change in the density in one direction or another; of the inversion zone and zone of constant density was taken into consideration. The density of rated bodies on the surface of the basement was defined based on the percentage ratio of the constituent rocks; in the depth — from the dependence of density on velocity. The block structure of the Earth’s crust upper part; which was previously revealed by seismometry in some areas of the zone; was confirmed. During the modeling it was found out that the structure of investigated territory in the density model from the surface to a depth of ³ 20 km is divided into the central; eastern and western parts. The central one; which corresponds to the most part of the Golovanevsk suture zone; is represented by rocks; whose density is much higher than in the western and especially in the eastern parts. The existence of essentially decompacted rocks in the eastern and northern parts of the zone to a depth of 10 km indicates the presence of granitization processes in the past. From the depth of 30 km and up to the Moho discontinuity two parts are distinguished: the western and the eastern. These parts are separated by a sharp submeridional stage in the Moho discontinuity from 46 to 55—65 km; which are traced along the center line of the Golovanevsk suture zone. The density of rocks is much higher in the western part both in area and with depth. The density distribution across the entire crustal section was obtained both in local structures with an abnormally high density on the surface of the basement (represented by gabbro amphibolites; ferruginous quartzites; crystal shales and gneiss garnet-biotite gneisses) and in the enclosing rocks. The performed calculations made it possible in the first approximation to determine the nature of the density variation with depth in the anomalous structures and to establish the depth of their propagation. According to preliminary data; these structures can be traced to a depth of 3—5 km.