Seismological characteristics of the earth's crust of southeastern part of the Phennoscandinavian shield (Russia)

Шаров, Н. В.; Куликов, В. С.; Куликова, В. В.; Isanina, E.V.; Krupnova, N. A.

doi:10.24028/gzh.0203-3100.v32i3.2010.117526

Cited by 2 publications

(1 citation statement)

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“…Reflection seismic studies suggest that the Belomorian Province comprises a stack of eastward dipping subhorizontal nappes and thrusts, being separated from the underlying Karelia Province by a major detachment zone. These structures have been interpreted to represent collisional thickening during the Paleoproterozoic [24][25][26].…”

Section: Fennoscandiamentioning

confidence: 99%

Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield

et al. 2020

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The Tuntsa Suite is a polymetamorphic Archean complex mainly consisting of metasedimentary gneisses. At least two strong metamorphic events can be distinguished in the area. The first took place at high temperatures in the Neoarchean at around 2.70–2.64 Ga, indicated by migmatisation and U-Pb ages of metamorphic zircon. During the Paleoproterozoic, metasedimentary gneisses were penetratively deformed and recrystallized under medium pressures producing staurolite, kyanite and garnet-bearing mineral assemblages. The suggested Paleoproterozoic PT path was clockwise where the temperature and pressure first increased to 540–550 °C and 6 kbar, crystallizing high Ca/low Mg garnet cores. The mineral compositions show that commonly garnet core was not in chemical equilibrium with staurolite but crystallized earlier, although garnet-staurolite-kyanite assemblages are common. The temperature and pressure increased to c. 650 °C and 8 kbars where staurolite and kyanite coexist. This was followed by decompression down to c. 550–600 °C and 3–4 kbars, shown by andalusite crystallization and cordierite formed in the breakdown of staurolite and biotite + kyanite. The observed garnet zoning where Mg increases and Ca decreases from the core to the rim was developed with both increasing and decreasing pressure, depending on the effective bulk composition. The U-Pb and Sm-Nd age determinations for monazite and garnet show that the Paleoproterozoic metamorphic cycle took place at 1.84–1.79 Ga, related with thrusting of the Lapland granulites onto the adjacent terranes and subsequent exhumation.

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Section: Fennoscandiamentioning

confidence: 99%

Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield

et al. 2020

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Seismic model of the Earth's crust and upper mantle beneath the Fennoscandian Shield

Lebedev

Шаров

2023

E3S Web Conf.

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Well-founded concepts of the crust and upper mantle structure of the Fennoscandian Shield were developed. Quantitative evidence for horizontal and vertical lithospheric heterogeneities was obtained. Highly detailed integrated geological and geophysical investigations, supported by superdeep drilling, have been conducted in the eastern part of the shield in recent years. Seismogeological crustal models of individual geotectonic provinces were constructed, which indicate that the structure of the crystalline crust displays a pattern of blocks, arranged hierarchically, with no persistent seismic boundaries across the entire shield. Both low- and high-velocity zones, correlatable with geological bodies, occur locally. The structural plans of contours and the velocities of various deep sections were shown to be inconsistent. We conclude that the upper mantle is laterally complex and heterogeneous, and that there is no asthenosphere in the classical sense of the word.

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Seismological characteristics of the earth's crust of southeastern part of the Phennoscandinavian shield (Russia)

Cited by 2 publications

References 1 publication

Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield

Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield

Seismic model of the Earth's crust and upper mantle beneath the Fennoscandian Shield

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