Jerzy Jankowski

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

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 geoelectrical strike of N60 degrees 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 midcrustal depths. The upper mantle of the Precambrian East European Craton is more resistive than, adjacent to the West, the younger Paleozoic Platform.

Anomalous induction in the Carpathians

РезюмеОnuсывaюmся резульmamы uзученuя вaрuaчuŭеомaнumноо nоля зaреuсmрuровaнных о¶rt;новременно нa 9 nолевых сmaнцuях в¶rt;оль nрофuля ГСЗ No V, nересекaющео Кaрnamы. Деmaльно uзучaеmся зонa aномaльноŭ uн¶rt;укцuu нaрaнuце меж¶rt;у внещнuмu u ценmрaльнымu Кaрnamaмu. Посmроены векmоры uн¶rt;укцuu u aнaлuзuровaнa чaсmоmнaя хaрaкmерuсmuкa aномaльноо эффекma. По ¶rt;aнным нa оm¶rt;ельных сmaнцuях о¶rt;новременно зaреuсmрuровaнных возмущенuŭ осущесmвляеmся рaз¶rt;еленuе nоля нa внуmреннюю u внешнюю сосmaвляющuе. Оценuвaеmсялубuнa зaлеaнuя сосре¶rt;оmоченноо лuнеŭноо элекmрuческоо mокa, коmорыŭ являеmся о¶rt;нuм uз возможных uсmочнuков внуmреннео nоля. Элекmромaнumные хaрaкmерuсmuкu nоля соnосmaвлены с mеореmuческuмu aномaлuямu рaсчumaннымu ¶rt;ля некоmорых ¶rt;ву-мерно нео¶rt;норо¶rt;ныхеоэлекmрuческuх сmрукmур в¶rt;оль nрофuля чuсленным меmо¶rt;ом конечных рaзносmеŭ.

Probing electrical conductivity of the Trans-European Suture Zone

The Trans-European Suture Zone (TESZ) is the largest tectonic boundary in Europe, crossing northwest-southeast through central Europe from the North Sea to the Black Sea. More than 2000 kilometers long, it constitutes a complex transition between the thick and cold East European Craton (EEQ/Baltic Shield, created more than 650 million years ago (Ma) during the Precambrian, and the warmer, younger Paleozoic (650 to 250 Ma) central European mobile belts.

Electromagnetic Induction Profile (PREPAN95) from the East European Platform (EEP) to the Pannonian Basin

Complex electromagnetic measurements along a profile crossing different great tectonic units in East-Central Europe (East European Platform, Paleozoic Europe and Carpatho-Pannonian region) were carried out by Hungarian, Polish, Slovak and Ukrainian institutes. Beside recent MT sounding curves, geomagnetic induction vectors, polar diagrams, apparent resistivity and phase pseudosections, a short description of earlier magnetotelluric (MT) and magnetovariational (MV) experiments is also given. For interpretation of these data 1D and 2D inversions were used after separation of the quasi E and B polarized curves. The Carpathian conductor clearly appears in the magnetovariational profile. MT soundings indicate that the mantle conductive basement — presumabely the asthenosphere — steeply deepens from the Neogene Pannonian Basin characterized by high heat flow towards the much colder EEP through the Paleozoic area.

Induction vector estimates in the Polish-Czechoslovak part of the Carpathians

РезюмеПрuво¶rt;umс я сво¶rt;нaя maб лuцa векmоров uн¶rt;укцuu nолученных в резульmamе обрaбоmкu nо левых мaнumо вaрuaцuонных ¶rt;aнных нa nо льско-чехословaцко м учaсmке Кaрnam.

Natural Variations of the Geomagnetic Field: Observations and Application to Study of the Earth’s Interior and Ionosphere

The magnetic investigations carried out incessantly from the very moment the Institute of Geophysics was established in 1953 are outlined. Since that time, continuous observations of the natural magnetic field of the Earth, also called “magnetic service”, have been carried out. The research methods are discussed, which cover a wide scope of problems relating to the use of natural electromagnetic field variations, including the recognition of the Earth’s crust and upper mantle, search for electromagnetic earthquake precursors, and the ionosphere state monitoring via surface-based observations of the magnetic field. The reported investigations are of methodological nature, relating to recording and processing of data, as well as geophysical and geological modeling and interpretation. The major results obtained during 60-year activity, referring to the structure of the Earth’s crust and mantle in central Europe, are summarized.