Magnetic model for the earth's crust under the Ukrainian Shield

Abstract

A magnetic model for the crust under the Ukrainian Shield is proposed and the following aspects of its construction are discussed: (1) technique of separation of the regional component of the anomalous magnetic field; (2) estimation of rock magnetization and distribution of the sources of anomalies within the earth's crust; (3) Modelling of the crustal effect with the given distribution of magnetization; and (4) correlation of the regional component with crustal thickness and depth to Curie point isotherm of magnetite.Two ferromagnetic layers are established within the crust. Average magnetization of the upper crust ranges from 0.1 × 10−3 to 0.6 × 10−3 emu for different blocks. Magnetization maximum for the lower crust is 4 × 10−3 emu, the value being supported by different methods.Inhomogeneities with maximum magnetization of 6.5 × 10−3 emu are found within the lower crust.In the areas of regional highs the earth's crust is the thickest, the Moho discontinuity layered, and the distribution of magnetization anomalous for all depths.The stated correlation of regional component with crustal thickness may be of value in predicting the Moho topography.