EXPERIENCE OF MULTIFACTOR LOCAL FORECASTING ON EXAMPLE OF THE GOLUBINSKO-OLLAMINSKOE NEPHRITE FIELD (REPUBLIC OF BURYATIA)

The traditional formation and geotectonic method of forecasting is ineffective when carrying out prospect evaluation survey and exploration development works as these works are carried out on small-sized objects located within the same geotectonic region on the development area of one formation. Under these conditions, it is necessary to attract indirect prospecting factors that reflect the probabilistic nature of the relationship between the mineragenesis processes and geological complexes of various types. This is especially true for nephrite deposits, which generally belong to small and ultra-small objects with a very limited amount of reserves. This paper presents the experience of local multifactorial forecasting of the Golyubinsko-Ollaminskoe nephrite field. The low efficiency of traditional forecasting methods using mineragenic factors of the first kind is shown. It is proposed to carry out local forecasting of nephrite using the mineragenic factors of the second kind and indirect prospecting factors, which are not reflected on the source maps but are informative on the probability of the presence or absence of nephrite deposits. Their potential nephrite content is evaluated using the methods of mathematical statistics. Mineragenic zoning of the area is performed by compiling a multifactor forecast map with the specification of areas with varying degrees of prospects. The following phasing of local forecasting is implemented: the geological structure of the area is analyzed and nephrite-controlling structural and material complexes are classified as mineragenic factors of the second kind; indirect search features are identified; assessment is given to the informative content of various controlling factors and total informativeness of the sections of the combination of features of each category of factors. Single-factor forecast maps and a multi-factor forecast search map of the Golyubinsko-Ollominskoe field nephrite content is compiled. The proposed forecasting methods even on a limited amount of initial geological data allows area zoning according to the degree of prospects and identification of sites for nephrite search.

nephrite, local multifactorial forecasting, informativeness of geological features, Golyubinsko-Ollaminskoe field

1. Kochnev A.P., Krasnov D.A. Nephrite-bearing factors of GolyubinskoeOllaminskoe nephrite-bearing field (Buryat Republic). Izvestiya Sibirskogo otdeleniya Sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya, razvedka i razrabotka mestorozhdenii poleznykh iskopaemykh [Proceedings of the Siberian Department of the Section of Earth Sciences of the Russian Academy of Natural Sciences. Geology, Exploration and Development of Mineral Deposits], 2017, vol. 40, no. 1, рр. 52–65. (In Russian).

2. Burtseva M.V., Ripp G.S., Posokhov V.F., Murzintseva A.E. Nephritis of East Siberia: geochemical features and problems of genesis. Geologiya i geofizika [Russian Geology and Geophysics], 2015, vol. 56, no. 3, рр. 516–527. (In Russian).

3. Zamaletdinov R.S. Methods of nephrite deposit prospecting and exploration. Razvedka i okhrana nedr [Prospect and Protection of Mineral Resources], 1975, no. 7, рр. 18–24. (In Russian).

4. Suturin A.N., Zamaletdinov R.S., Sekerina N.V. Mestorozhdeniya nefritov [Nephrite deposits]. Irkutsk: Irkutsk State University Publ., 2015, 377 р. (In Russian).

5. Shere R.L. Geology of the Sagecreek nephrite deposit. Wyoming: Contributions to Geology (University of Wyoming), 1972, vol. 11, no. 2, рр. 83–86.

6. Harlow G.E., Sorensen S.S. Jade: Occurrence and metasomatic origin. Extended abstract from International Geological Congress 2000, 2001, рр. 7–10.

7. Harlow G.E., Sorensen S.S. Jade (nephrite and jadeitite) and serpentinite: metasomatic connections. International Geology Review, 2005, vol. 47, рр. 113–146.

8. Cooper A.F. Nephrite and metagabbro in the Haast Schist at Muddy Creek, Northwest Otago, New Zealand. New Zealand Journal of Geology and Geophysics, 1995, vol. 38, рр. 325–332.

9. Kochnev A.P. Features of solid minerals local prediction. Izvestiya Sibirskogo otdeleniya sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya, poiski i razvedka rudnykh mestorozhdenii [Proceedings of the Siberian Department of the Section of Earth Sciences, Russian Academy of Natural Sciences. Geology, Prospecting and Exploration of Ore Deposits], 2016, no. 1 (54), рр. 33–44. (In Russian).

10. Kochnev A.P., Yurenkov E.G. Fundamentals of forecasting and prospecting models typification. Izvestiya Sibirskogo otdeleniya sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya,

11. poiski i razvedka rudnykh mestorozhdenii [Proceedings of the Siberian Department of the Section of Earth Sciences, Russian Academy of Natural Sciences. Geology, Prospecting and Exploration of Ore Deposits], 2014, no. 1 (44), рр. 74–80. (In Russian).

12. Bugaets A.N., Dudenko L.N. Matematicheskie metody pri prognozirovanii mestorozhdenii poleznykh iskopaemykh [Mathematical methods under prediction of mineral deposits]. Leningrad: Nedra Publ., 1976, 270 р. (In Russian).

13. Vysokoostrovskaya E.B., Zelenetskii D.S. On quantitative assessment of the area prospects when searching for mineral deposits. Sovetskaya geologiya [Soviet Geology], 1968, no. 8, рр. 58–71. (In Russian).