Kompleksowa interpretacja wyników badań geofizycznych dla strefy Gopło-Pabianice ze szczególnym uwzględnieniem utworów cechsztynu i podłoża

Abstract

A COMPLEX INTERPRETATION OF THE RESULTS OF GEOPHYSICAL ANALYSES IN THE GOPŁO – PABIANICE AREA WITH SPECIAL EMPHASIS ON ZECHSTEIN DEPOSITS AND THEIR BASEMENT

Summary

A complex interpretation of the results of geophysical investigations in the Gopło – Pabianice area was made in order to obtain more information about the deep geological structure of this region, characterized by intensive salt tectonics, and to examine the possibilities of interpreting different geophysical methods.

Special emphasis was laid on a fuller investigation of salt deposits of the Zechstein as well as of the sub-Zechstein and consolidated basement. The main methods used in the present investigations were the seismic reflection and refraction methods and the gravity method. The results of seismic reflection method provided a general picture of the geological structure of the area concerned and of the local structures, but the characteristic of Zechstein deposits thus obtained was not complete. The results of regional refraction method were the reinterpreted, and on this basis a tentative picture of the morphology of the consolidated basement was formed. The results of gravity measurements were also available but their interpretation encountered considerable difficulties.

Analyses of the measurements of density provided the basis for creating the general density model. Geological structures in this area present a compensated picture on gravity maps and this leads to difficulties in the interpretation of gravity measurements. The same conclusions were reached when the picture of geological structure, based on seismic materials, was correlated quantitatively with the picture of gravimetric anomalies.

In order to obtain quantitative data the authors made a detailed interpretation of thirteen two-dimensional seismic-geologic-density models.

All the data obtained were compiled and correlated and thus the following conclusions were reached:

1. Salt deposits occur in the cores of almost all the Mesozoic anticlines recorded in the area. The authors were able to trace the continuity or the joining of these anticlines.

2. The correlations established here indicate a genetic relationship between salt structures and dislocations in the sub-salt horizon.

3. Arelationship has been established between the old, regional dislocation zone (which faulted down the consolidated basement about2000 m, and which runs along the Gopło – Poddębice – Pabianice line), the thick sub-Zechstein sediments, and the most intensive development of salt tectonics.

The most important methodical conclusion, reached in the present study is the great effectiveness of a complex interpretation of the results of gravity measurements and seismic reflexive data. The use of data concerning gravity only is not very effective and does not lead to explicit conclusions.