Deep Structure and Geodynamics of the Sarmatia–Fennoscandia Transition Zone

• Дата: 2026
• Автори: Gintov, Oleg, Mychak, Sergii, Babynin, Oleksii
• Формат: Стаття
• Мова: Англійська
• Опубліковано: S. Subbotin Institute of Geophysics of the NAS of Ukraine 2026
• Теми: Sarmatia; Fennoscandia; Svecofennian orogen; Ukrainian Shield; transition zone; mantle; subduction
• Онлайн доступ: https://journals.uran.ua/geofizicheskiy/article/view/344412
• Назва журналу: Geofizicheskiy Zhurnal

The geological structure of the crust and mantle within the transition zone between the Sarmatia and Fennoscandia miniplates, which encompasses the central and southern parts of the Svecofennian orogen and the northwestern segment of the Ukrainian Shield was examined. The transition zone is extended south-eastward to include several northeast-striking fault zones of the Ukrainian Shield (from the Horyn to the Teteriv fault zones, inclusive). Crustal interpretations rely on recent publications by Swedish, Polish, Estonian, Lithuanian, Belarusian, and Ukrainian researchers [Bogdanova et al., 2015; Mężyk et al., 2021; Garetsky & Karataev, 2011; Shumlyanskyy et al., 2018]. The mantle down to 850–2500 km depth is investigated using a 3D velocity model for Eurasia developed at the S. I. Subbotin Institute of Geophysics National Academy of Sciences of Ukraine based on seismic tomography with a Taylor approximation to the eikonal and wave equations [Geyko, 2004]. It is showed that the Sarmatia–Fennoscandia transition formed in the Paleoproterozoic (2.1–1.75 Ga) through complex geodynamic processes evidenced by multiple subducted mantle slabs. A key process was the subduction of Fennoscandia beneath Sarmatia, recorded by a south-dipping slab from the Keitele microcontinent beneath the Bergslagen microcontinent and the Mid-Baltic Belt, and by an east- to southeast-dipping slab beneath Sarmatia from the Belarus–Podlasie Granulite Belt beneath the Osnitsk–Mikashevichy Igneous Belt and the area of the present-day Korosten Pluton. Subduction occurred with interruptions, one of which (ca. 1.89–1.84 Ga) coincided with formation of the Baltic part of the Svecofennian orogen via additional subduction of opposite polarity (north and northeast), as confirmed by slabs from the Amberland microcontinent beneath the Bergslagen microcontinent and from the Central Finland Arc Complex beneath the Karelian craton. Thus, reconciling upper-mantle seismotomographic observations with geological–geophysical constraints on crustal evolution provides compelling evidence for a plate-tectonic origin of the processes that led to the formation of the East European Craton.