FEATURES OF GRAVITY FIELD TRANSFORMATION AND INVERSION USING VARIANCE AND REGRESSION ANALYSES

Abstract

The Purpose of the paper is to study the possibilities of regression and variance analyses under quantitative interpretation of gravitational anomalies. Methods. On example of the Ulanbaatar and Nalaikh intermountain depressions (Mongolia) the application possibilities of the principal component method and the pseudo-inverse algorithm under the transformation and inversion of gravitational fields are considered. Results. The quantitative characteristics of the thickness of loose deposits of the structures under investigation are obtained through regression and variance analyses. The maximum thickness of the deposits of the Ulanbaatar depression is 100-200 m whereas the Nalaikh depression is 600 m. The obtained estimates are confirmed by the results of investigated depression gravitational field inversion by other methods. Conclusions. The transformation and inversion results of the gravitational field of sedimentary deposits of low thickness (100-200 m) when replacing infinite length rectangular prisms by the parallelepipeds limited along the strike vary insignificantly and remain within the initial limits (while maintaining the magnitude of the lack of density). The depression filled with the sediments of great thickness features a significant increase in this characteristic (from 600 m to 900 m) while maintaining the lack of sediment density. Such variations in the sedimentary thickness of the studied objects can be explained by the magnitude of the visibility angle of individual geometric bodies approximating precipitation lenses. It is found that the application of the method of principal components of the variance analysis in the identification of the regional and local (residual) components of the gravitational field and the inversion of the anomalous gravity field using a pseudo-inverse algorithm of the regression research method are quite possible and effective.