Profil mikromagnetyczny przez Góry Świętokrzyskie

Abstract

Przedstawiono historię badań magnetycznych w Górach Świętokrzyskich. Omówiono zakres i metodykę pomiarów mikromagnetycznych, wykonanych w 1969 r. wzdłuż profilu ,przechodzącego w poprzek trzonu paleozoicznego Gór Świętokrzyskich i części jego mezozoicznego obrzeżenia, a także sposób opracowania uzyskanych wyników. Zestawiono i przeanalizowano wyniki badań ,własności magnetycznych utworów paleozoicznych Gór Świętokrzyskich. Zbadano charakter anomalii magnetycznych nad poszczególnymi jednostkami stratygraficzno-litologicznymi tego regionu. Stwierdzono, że badania mikromagnetyczne mogą być wykorzystane do kartowania niektórych granic tych jednostek i uskoków.

MICROMAGNETIC PROFILE ACROSS THE GÓRY ŚWIĘTOKRZYSKIE

In 1969 micromagnetic measurements were completed in the Góry Świętokrzyskie; they were performed on the commission of the Geological Institute by a Research team of the Geophysical Department Polish Academy of Sciences, supervised by Z. Mrukowski. The SW - NE micromagnetic profile ran across the entire Palaeozoic core and a part of its Mesozoic cover. The purpose of the measurements was to determine which geological boundaries could be traced by micromagnetic techniques. The PMP magnetometer constructed at the Geophysical Detpartment was used. Observations were carded out on 19 500 points along a 40 km profile line, the distance between the points was 2 m, and average accuracy ±1 gamma.

The . history of the magnetic surveys completed in the Góry Świętokrzyskie for geological purposes is presented in the paper.

The micromagnetic techniques and the methods of reduction and data Processing are discussed.

The results served to construct a graph of mean values of the magnetic field intensity anomalies calculated for 100 m portions of the profile and were plotted against the geological cross-section; in addition, graphs of selected local anomalies observed above the stratigraphic boundaries and faults were made.

The magnetic properties of Palaezoic rooks were compiled and analyzed.

The nature of the anomalies observed above different lithological-stratigitraphic units has been studied. The values of the periods and amplitudes of the magnetic anomalies resulting from different geological sources have been estimated. It has been found that without additional geological data the amplitude-frequency analysis of micromagnetic results hardly ever provides unambigous informations on the geological source of the anomalies.

Micromagnetic measurements completed in 1969 in the Góry Świętokrzyskie proved useful for the mapping of sediment sand for tracing certain lithological-stratigraphic boundaries, and faults in particular. These techniques can also be used to examine iron ore zones and igneous rocks of poor magnetic susceptibility. A reliable interpretation·of micromagnetic results must be based on all the available geological data combined with magnetic parameters of rocks.