European tectonic features observed by Magsat

Abstract

Regional three-dimensional magnetic models have been developed to characterize the principal European long-wavelength magnetic anomalies represented on the improved Magsat magnetic anomaly map of Europe. The magnetic models were constrained by regional variations in geology and geophysical parameters (e.g., geologic boundaries, crustal thickness, heat flow). Because only limited measurements of magnetization are available on lower crustal and uppermost mantle rock samples, our results are useful in constraining and understanding the overall magnetization of these regions. Illustrations of these include: (1) geologic provinces across the Tornquist-Teisseyre tectonic zone; (2) regions of thin crust and high mantle heat flow in south-central Europe; (3) the Kursk-Voronezh magnetic anomaly; and (4) the Ladoga-Gulf of Bothnia zone. The region of the Tornquist-Teisseyre tectonic zone, that marks the boundary between the Fennoscandian-Baltic Shield and metastable Europe, is a major magnetic discontinuity. In south-central Europe, the regional magnetic variations appear to be directly related to variations in the lower crustal thickness and possibly also to heat flow. In addition, the famous Kursk (Ukraine) iron-ore deposit produces a prominent bullseye anomaly at satellite altitude. The Kiruna Magsat anomaly is modelled as having a large, deep body as its source. The high P-wave velocity, basal crustal layers encountered in rift (e.g., the Tornquist-Teisseyre tectonic zone itself) and continental arc (e.g., the Ladoga-Gulf of Bothnia zone) settings of Europe appear to be nearly non-magnetic.