The method to construct the 3D density model included the reduction of the deep boundaries’ effect on the observed gravityl field and the calculation of the 3D effective density distribution from the residual field. The deep surfaces were built on the seismic data of DSS and CCP profiles available for the area under study. These surfaces formed the basis of the geometry of the 3D five-layer density model with a constant density on the top of the layer and gradient density changing with the depth. For the reduced field the inverse gravity problem has been solved and the distribution of the effective density in the earth’s crust has been obtained. A number of equivalent 3D distributions of effective density depending on the chosen inversion parameters have been constructed. The choice of a specific composition was based on the comparison of the obtained density distribution with seismic models on the DSS profiles. The resulting 3D density model has been obtained as a sum of the 3D gradient model from the deep boundaries and the 3D model of the effective density distribution.
The analysis of the obtained 3D density model has allowed to make a number of conclusions on the deep crustal and upper mantle structure of the southeastern part of the Fennoscandian shield.

Pimanova Nadezhda Nikolaevna, Ph.D. Leading Researcher. department of “Geoinformatics” “VNIIgeosystem” FGBU “VNIGNI”. 117105, Moscow, Varshavskoye sh., 8. E-mail: nadja@geosys.ru.

Spiridonov Viktor A., candidate of technical Sciences, head. sector «software Development» branch “Geoinformatics” “Vniigeosistem” FGBU “VNIGNI”. 117105, Moscow, Warsawskoe sh. 8. E-mail: victor@geosys.ru.

Sharov Nikolay Vladimirovich, doctor of geological-mineralogical Sciences, head of laboratory of Geophysics, Institute of Geology, KarRC RAS. 185910, Petrozavodsk, Pushkinskaya str., 11, KarRC RAS.E-mail: sharov@krc.karelia.ru.

Mitsyn Sergey Valerievitch, research scientist Division of geoinformatics «VNIIGeosystem», FGBU «VNIGNI». E-mail: smitsyn@yandex.ru.

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