Geophysical Journal | 2001 volume 23 3

A velocity model of the Earth's crust and upper mantle of the Korosten Pluton (Ukrainian Shield) and its geological interpretation (along the DSS profile Shepetovka-Chernigov)

© Ilchenko T.V., Bukharev V.P.

A detailed DSS surveying (with 100 m spacing of receivers and 10 - 30 Hz frequency range) along the SW - NE directed profile Shepetovka-Chernigov has provided a database for the P-wave velocity model of the Earth's crust and uppermost mantle of the Volhyn Block in the NW Ukrainian Shield, including the anorthosite - rapakivi Korosten Pluton, and the northern margin of the Ros-Tikich Block. The distinctive feature of the upper crust is an alternation of low- and high-velocity layers, with the highest values within the latter in the Korosten Pluton. The lower crust is characterized by a gradual vertical velocity growth. The Korosten Pluton is manifested there as a nearly homogeneous block with velocity of 7,0 km/s that is higher than within the adjacent blocks. However, this positive velocity anomaly reduces with depth, practically disappearing in the bottom of the crust. The obtained peculiarities of the velocity distribution suggest the crustal derivation of the geostructure. The supposition is confirmed by petrostructural, mineralogy-petrographical, and geochemical properties of its anorthosite formation rocks.

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