Search-oriented technique of the numerical forecasting of the gold placers: evidence from the Vagran placer district

As a result of field research, as well as analysis of data from stock reports, two types of placer gold were identified within the Vagran placer cluster of the Northern Urals, which are indicators of primary mineralization of gold-sulfide-quartz and hypogene-hypergene types, which were used as benchmarks for developing a digital system for predicting parameters and localizing primary sources of placer gold. In the present work the typomorphic characteristics of placer gold (size, roundness, sorting and fineness, as well as the content of impurity elements) are formalized (in the form of a quantitative assessment). These data were processed using the methods of multiplicative indicators, linear regression method and a regression tree method using a random forest algorithm, which make it possible to forecast the composition and localization of the primary mineralization with greater confidence and stability than ordinary parameters separately. The data required for such an assessment do not require additional field and highly qualified laboratory studies, they are contained in standard reports on the heavy minerals testing. The study of the correlation matrix allowed to identify characteristic indicators for the primary mineralization of gold-sulfide-quartz and hypoge- nic-hypergenic types, and to give recommendations for conducting prospecting and exploration in order to identify the primary gold content of the cluster. All three methods used gave consistent results that make it possible to predict the parameters of primary gold content, while the method of calculating multiplicative coefficients gives a more contrasting, pronounced result, seems to be the simplest and most generalized, suitable for any set of consistent data, while other methods require a more in-depth analysis incoming parameters. The proposed method of creating forecast estimates allows to increase efficiency and partially automate the process of determining the prospects for primary mineralization of territories.

placers, strategic metals, gold, multiplicative indicators, forecast model