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METHODS OF SMOOTHING AND FILTERING GEOLOGICAL AND GEOPHYSICAL DATA

Laurențiu Asimopolos

Abstract

In this paper we presented the calculation algorithms and the software for the calculation of the moving average with various windows, for calculating the analytical expressions of the polynomial tendencies of various degrees and for the calculation of the correlation factor variation between two parameters. Trend analysis is part of the field of regression analysis that satisfies the smallest squares criterion. The difference between the calculated value of the trend surface at a certain point and the value observed at that point is the residual value. If moving averages or trending surfaces are considered to be the regional or large-scale component, then the residual value is the local or small-scale component. The removal of the regional trend has the effect of highlighting the local components represented by residual values. Principles of trend surface analysis are also applicable to hyper-surfaces in any dimensions. A surface occupying a three-dimensional space is a mathematical function with a dependent variable and two independent variables. We can operate mathematically with four or more variables, that are of major importance in applications where we want to investigate more geological or geophysical parameters. Viewing spatial relationships in a three-dimensional space is very difficult. The best method is to assign a constant value to an independent parameter and to represent the parameter that depends only on two independent parameters, as in the case of trending surfaces. This type of representation is the general trend of the parameter dependent on two independent parameters. Typically, the dependent parameter is a geological or geophysical parameter and the two independent parameters are latitude and longitude. Depending on the degrees of the calculated trend, we can get the effect of the filters on anomalies. The high pass filters are obtained by the difference between the initial values (measured) and the values calculated for the trending surface in the same nodes of the network. The band pass filters, are obtained by the difference between the calculated values for two levels of degrees for trend surfaces in the same nodes of the network. Low pass filters are represented by the values calculated from the surface analytical expressions of the network nodes used. In the paper we have exemplified these methods for a test area, copper mine Assarel Medet near Panagyurishte, in the project Real-Time Mineral X-Ray Analysis for Efficient and Sustainable Mining, acronym: X-MINE.

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DOI resolver: doi.org/10.5593/sgem2018/1.1/s01.031

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