Geological and biological aspects of a find of natural alloy (Au-Cu-Ag) nanoparticles in Cenozoic zeolitized tuff of the Vanchinskaya basin (Primor’e Area)

Abstract

Zeolites first described by Swedish researcher Kro� nshted more than 250 years ago still attract special attention today. These minerals are effectively applied in industry, agriculture, medicine, and for conserva� tion of surroundings with gradually spreading areas of their application. This is explained by unique adsorp� tive, ionexchange, and catalytic properties typical for this group of minerals, as well as by their thermal, chemical, and radiation stability. Artificial zeolites with constant composition and a strictly definite set of physicochemical properties are claimed in industry. Natural zeolites represented by polymineral zeolitized rocks (zeolitites) of various geneses are applied in agri� culture and medicine. In spite of their old origin, the mechanism of biological activity of these natural min� eral systems still is not sufficiently studied. The discov� ery of natural Au-Cu-Ag alloy microparticles in nat� ural zeolitites discussed in this paper is a rare mineral� ogical fact deserving special attention. The Vanchinskaya basin, one of the Cenozoic rift� ogene basins within the Eastern SikhoteAlin' volca� nic belt, has a relatively small size of 4 × 15 km. How� ever, the presence of coal and zeolites volcanogenic- sedimentary deposits filling it, high registered concen� trations of REE in coals (1), and its location on the southeastern flange of the Soyuznoe gold-silver deposit (2) are responsible for the unremitting scien� tific and practical interest in it over many years. Structurally this basin is a oneside riftogenic gra� ben of northwestern strike. Its southwestern side is separated by the Milogradovskii fault (thrust) clearly reflected in relief. The northeastern flange occurring along the fault as well is gentle. The western part of the basin is filled by pyroclastic (tephrogenic) and tuffo� gene-sedimentary coalbearing deposits of Pale� ocene-Early Eocene age. In the eastern part they are replaced and intruded by Middle Eocene volcanic rocks (tuffs, lavas, explosive breccias, and extrusive rhyolite and trachyandesite bodies). Zeolite mineralization within the basin has a strat� iform character. All zeolitite occurrences on the right side of the Vanchina-Ugol'nyi Brook including the Berezovoe manifestation studied in detail are of the same type by geological characteristics. They are rep� resented by outcrops (fragments) of the undercoal band of tuffaceous sandstone and tuffite in the compo� sition of tuffogene-sedimentary lake deposits and characterized by a significant admixture of mineral� ized plant detritus. According to the data of Xray structural analysis, the mineral composition of zeoli� tites of the Berezovoe manifestation comprises zeolites of the clinoptilolite-heulandite group (50-60%) and clay minerals of the smectite group (20-30%) with an admixture of quartz and feldspars. The visible thick� ness of the zeolitebearing band is ~20 m. Clearly reflected signs of active eating of rocks by wild ungulates as lick niches, as well as eaten away caves and individual nibbles on outcrops with typical tooth prints are observed in the coldfree period of the year on all natural outcrops of the zeolitized band within the Vanchinskaya basin. Traces of Manchurian deer are the most frequently observed among the traces left by animals in the places where they eat rocks and soils. As we mentioned before, most of the soils eaten by animals within the SikhoteAlin' are formed from zeolitized and argillized tuffogene-sedimentary rocks with clear signs of the presence of buried organic rem� nants (3). The hypothesis on the significance of organic materials in zeolitites as accumulators of bio� logically active chemical elements appeared long ago,