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Geoinformatika 2019; 4(72) : 59-64

УДК 550.8

THE PRACTICAL USE OF THE ANALYTICAL MODEL OF THE GRAVITATIONAL FIELD IN GEOLOGICAL INTERPRETATION

T.L. Mikheeva, E.P. Lapina, N.V. Panchenko

<S.I. Subbotin Institute of geophysics NAN of Ukraine, Kiev, Ukraine

Purpose.To conduct a qualitative interpretation of the initial gravimetric data, an automated system for interpreting potential fields was used. During the research, the following tasks were solved: a numerical model of the anomalous gravimetric field was constructed and a qualitative interpretation of the results was obtained, local anamaly-forming sources were modeled. The proposed algorithm allows to significantly reduce the number of required parameters and to bring the solution as close as possible to a real geological environment. The developed software and algorithmic software has been tested on model examples and real areal gravimetric data.

Design/methodology/approach.Methods based on solving the inverse problem by the selection method, an approximation design is used, which is determined by a set of three-dimensional rod bodies. The orientation of the rods is consistent with the coordinate axes. The center of symmetry of each body can move. When solving the problem, the
centers of symmetry of bodies can determine the positions of geometric centers of rather complex figures. Three-core approximation makes it possible to better describe the integral characteristics of the geological model, as evidenced by the numerous model calculations carried out by employees of the department of mathematical geophysics.To combat the effect of ravine, an algorithm was used to select model parameters by groups, depending on their contribution to the functional. The maximum discrepancy between the observed and theoretical fields was 0,1 mGal. As a result, we obtained a model, the use of which will allow us to approximate the initial field at given points of the relief with a certain accuracy.

Findings. Results an example of approximation of the initial gravity field by an analytical function is considered. The study site is located in the Carpathian and Pre-Carpathian regions in size. The given gravity field at the relief points was approximated by some analytical function. As a result, an a posteriori interpretation model of the distribution of density inhomogeneities is obtained that satisfies both the observed field and a priori geological information. The sequential exclusion of density inhomogeneities makes it possible to obtain an anomalous effect from the region including the anomalous deposit more accurately. If in the anomalous field this effect is a small part, then in the residual field it can have a predominant value.

The practical significance and conclusions. The considered formulation of the inverse problem can be used to solve the interpretation problems of ore geophysics. Based on gravity anomalies, it is impossible to study the section area in which the deposit is located, omitting the study of heterogeneities located at shallow depths. Therefore, the detail and accuracy of solving problems are directly dependent on the complexity of the geological section. Further studies of this area will be aimed at determining local effects and identifying the boundaries of the region for direct searches and research using other geophysical methods.

Keywords: quality interpretation, inverse problem, automated system, analytical approximation, the gravimetric field, geological object

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Received 5/11/2019