Electromagnetic images of the deep structure of the Trans‐European Suture Zone beneath Polish Pomerania

Abstract

A large‐scale international electromagnetic experiment has been carried out in northwest Poland and northeast Germany. The main goal was to study the deep conductivity structure across the Trans‐European Suture Zone, which is the most prominent tectonic structure of Phanerozoic age in Europe. Electromagnetic measurements were carried out mainly along seismic profiles P2, LT‐7, and LT‐2 crossing the suture zone and running in the northeastern direction. Strike and dimensionality analyses indicate that a geo‐electrical strike of N60°W common to both profiles LT‐7 and P2 can be estimated. This strike direction was used to project and rotate all transfer functions and both profiles were subjected to 2D inversion using three different approaches. The results show the presence of highly conductive Cenozoic‐Mesozoic sedimentary cover reaching depths up to 3 km. A significant conductivity anomaly beneath the central part of the TESZ, called the Central Polish Anticlinorium, has been well resolved at mid‐crustal depths. The upper mantle of the Precambrian East European Craton is more resistive than, adjacent to the West, the younger Paleozoic Platform.

Seismic basement in Poland

“…The area of the Pomeranian part of TESZ is characterized by relatively low velocities of the uppermost basement (Vp ~ 5.85 km/s), and correlates well with the location of pronounced sub-horizontal conductor found by the electromagnetic studies (Ernst et al 2008;Jóźwiak 2013). The conductor has a resistivity as low as 2 Ωm, and is interpreted as Silurian-Cambrian metasediments.…”

“…The conductor has a resistivity as low as 2 Ωm, and is interpreted as Silurian-Cambrian metasediments. Its enhanced conductivity may be caused either by electronic conductors (graphite, alum shale) within Caledonian formations initially rich in coal facies, or by saline fluids (crustal brines) located most likely in the vicinity of deep fault systems (Ernst et al 2008).…”

Effect of a huge crustal conductivity anomaly on the H-component of geomagnetic variations recorded in central South America

“…This can be compared to the results of magnetovariational studies in other important suture areas. For example, in the Trans-European Suture Zone (TESZ), a major tectonic boundary in central-eastern Europe, the main conducting body lies at depths of the order of 10 km and with highly conductive sediments at the surface (Ernst et al 2008). In this case, the maximum response of the horizontal magnetic field is observed in periods of the order of 1000 s with amplitudes up to 1.8 (Habibian et al 2010).…”

Contrasting sources of Late Paleozoic rhyolite magma in the Polish Lowlands: evidence from U–Pb ages and Hf and O isotope composition in zircon

“…Refraction seismic data reveal that within this segment the crust has three layers: an upper layer of consolidated crust from 11 to 20 km, a middle layer at depths between 20 and 26 km, and a lower layer at depths of 26-36 km (Dadlez 2006). The nature of the upper-most part of the crust is also constrained by electromagnetic data, which indicate that it is dominated by Paleozoic metasediments (Ernst et al 2008;Jóźwiak 2013). This upper crust was penetrated by several boreholes and the deepest deposits were a clay to mudstone sequence of Ordovician age as well as Silurian shales and siltstones.…”