Prognostyczne szacowanie ilościowe złóż Zn-Pb w Polsce z zastosowaniem procedury Harffa-Davisa-Olea

Abstract

PROGNOSTIC QUANTITATIVE ESTIMATION OF ZN-PB DEPOSITS IN POLAND USING THE HARFF-DAVIS-OLEA PROCEDURE Summary The main goal of quantitative methods in the deposit evaluation is pointing the most perspective regions within the area being recognised through boreholes. Since many years the authors (Kotlarczyk et aI., 1988; Kotlarczyk & Mastej, 1993, 1995, Kotlarczyk, Mastej & Blaschke, 1994) present the results achieved by selected pattern recognition methods (Kora-3, potential function, K-nearest neighbours). Harff, Davis and Olea (1992) have presented the method of oil and gas deposits assessment by using the Mahalanobis' distance. The present paper is a trial of using the method for Polish Zn-Pb deposits. The testing ground was, as before, the exhausted part of deposit Pomorzany. Pomorzany mine is situated within Cracovian- Silesian region of Zn-Pb ore deposits. The deposits are of Mississippi Valey type. Within ore bodies occur irregular barren fields. The experiments were carried out for the data collected from 140 boreholes drilled in the first stage of prospection. The ore patterns of the predictor class 1 were selected from boreholes with a high content of metals while the pattern of predictor class 2 - from those completely free of metals and very low in them. At the same time the information on the ore and non-ore zones, shown by exploitation was ignored. In that way, the first stages of the geological prospection of the deposit were recovered. Among 23 features expressed in ratio scale, by Kullback method, there were 15 informative features selected. The resultant map (fig. 4) is highly consistent with the information achieved during the exploitation. Practically, the probability less than 0.3 indicates actual barren fields. Because of the tests conducted in the area of the exhausted part of the mine, the Harff-Davis-Olea procedure was positively verified.