Geophysical Journal | 2010 volume 32 5

Seismological cross-section of the Earth's crust along the profile DSS-CMP "Land-Sea" Kalevala-Kem'-the White Sea neck

© N.V. Sharov, A.I. Slabunov, E.A. Isanina, N.A. Krupnova, Yu.V. Roslov, N.I. Shchiptsova

The main goal of the studies was to develop a seismogeological model of the earth crust structure in the eastern Fennoscandinavian Shield by integrated analysis of geological data, vibroseismic CMP observation, using DSS on land, integrated sea seismic DSS and reflection survey-CMP monitoring. CMP and DSS and seismotomographic sections along 4B profiles; the southern portion of geotraverse 3-AR (Kalevala-Kem'-White Sea neck) have made it possible for the first time to study in detail the earth crust under the White Sea within the limits of the eastern part of Phennoscandinavian shield. Tectonic dislocation zones, extending to M-discontinuity, were delineated and traced downwards. The profile Kalevala-Kem'-White Sea extends across the Karelian, Belomorian, the southern part of the Kola province of the shield (including their joint zone) and Onega-Kandalaksha paleorift of the White Sea. In the upper part of the section on land portion of the profile within the joint zone of Belomorian and Karelian provinces the Shombozero structure of 70 km long with high velocity VP=6,1÷6,2 km/s which has a positive velocity gradient and within the joint zone of Belomorian and Kola provinces - Umbinsko-Kolvitskiy tectonic ensemble. The upper parts of the Earth's crust sections of the Belomorian and Karelian provinces have decreased velocity values of 5,7÷5,9 km/s. In the lower crust of the Belomorian and Kola provinces the increase of velocities VP=7,5÷8,9 km/s is noticed. The thickness of the Earth's crust of the region varies from 35 to 46 km.

<<back |