The Causes and Factors in the Genesis of Bonanza Ore Bodies in the Bakhmut Zone of the Pioneer Stockwork Gold Deposit (Amur Region).

When studying an ore shoot in the Bakhmut ore zone of the Pioneer mesothermal stockwork gold deposit (Amur Region, Russia) of vein-disseminated gold-quartz ores at its different levels, discrete anomalously gold-rich areas (bonanzas) were identified. The objective of the research was to investigate the causes and conditions for bonanza formation and the favored factors. Along with the analysis of the general distribution of gold in ore bodies, a detailed macro-and microscopic study of features on the distribution of native gold in ore samples and the nature of native gold was carried out. Gold particles are found to be hypogene in origin, including those at the surface. In the zones of brecciated rocks, a distinct spatial displacement of native gold accumulations upwards relative to a dense network of quartz veinlets and pockets and their almost complete absence in the quartz bodies indicate telescoping of high-grade gold accumulations formed at a single productive gold-quartz stage. At the same time, spatial proximity was established between fields of gold particle accumulation and quartz-filled fracture cavities that show dominance in size and zones where bulges of quartz-filled fractures tend to thin and pinch out. Our findings and laboratory experiments provided the data to develop the model of natural gas flotation of native gold nanoparticles as part of the "Aucr + gas," which associates with the formation of bonanzas under the above favorable conditions at higher levels of the deposit in the presence of different low permeability screens. [ABSTRACT FROM AUTHOR]