Forecast-exploration model of gold deposits of the Toupugol-Khanmeishor ore cluster as a basis for identification of promising areas for geological exploration within the Malyi Ural volcano-plutonic belt in the Polar Urals

A forecast-exploration model of gold deposits of the Toupugol-Khanmeishor ore cluster was developed, which made it possible to recommend geological exploration within other promising areas of the Malyi Ural volcano-plutonic belt (VPB) in the Polar Urals. The studies have demonstrated that the Manyukuyu and Kokpela potential ore clusters of the Tan’yu-Lagorta complex ore district in the southern Malyi Ural VPB represent the most promising targets for the further prospecting for lode gold mineralization assigned to various structural-compositional subtypes of the gold-sulfide-quartz mineral type.

Au-Ag-Te–RICH MELT INCLUSIONS IN HYDROTHERMAL GOLD-QUARTZ VEINS, XIAOQINLING LODE GOLD DISTRICT, CENTRAL CHINA

We present petrographic and microthermometric evidence for precipitation of Au-Ag-Te–rich melt directly from hydrothermal fluids and subsequent entrapment as primary melt inclusions within pyrite from quartz veins of the Xiaoqinling lode gold district, southern margin of the North China craton. We propose the formation of Au-Ag-Te–rich melt through adsorption-reduction mechanisms on pyrite and subsequent growth of the melt nuclei via direct scavenging of metals from fluids. Because neither initial formation nor later growth of the melt require saturation of the ore fluid with respect to the constituent metals, this mechanism offers a new understanding of the enrichment of low-abundance ore components, such as gold. Our model may thus partly explain the discrepancy between the high gold solubilities reported from experimental studies and the much lower gold concentrations usually measured in natural fluids. This study also implies that Au-Ag-Te–rich melt has probably gone unrecognized in other lode gold deposits in which Au-Ag tellurides are present.

The Lode Gold Occurrence in the «Territory» of Oleg Kuvaev (North of the Chukotka Upland)

A sample of a gold-bearing quartz vein from the Upper-Ichuveem ore occurrence, discovered in the Triassic terrigenous complex in the north of the Chukotka Upland, the Oleg Kuvaev's “Territory”, had been comprehensively studied. The gross gold grade was estimated at 3–4 g / t. The vein includes quartz, native gold, sulfide-goldsilver solid solutions, alumoseladonite, aluminium-sulfate-phosphates Fe-Pb-Mg-Ca compound, apatite, pyrite, iron-titanium oxides, litharge, native phases composed of Fe (Ni), Ag-Pb-Bi, Fe-Al-PS-As, multicomponent ocher of hypergene origin. Native gold ranges from medium to fine. The vein contains particles of non-crystalline organic matter, which is close in composition of organic groups to polysaccharides. It is possible that the carbon particles found in the gold-quartz vein are of an abiogenic nature and can be compared with abiogenic condensed organelles in the products of modern volcanism. The data obtained make it possible to attribute the Upper- Ichuveem gold ore occurrence to a low-sulfide gold-quartz formation, but with additional signs of gold-silver and polymetallic formations, which can be regarded as a favorable prerequisite for prospecting and exploration in Oleg Kuvaev's «Territory» not only of gold-placer deposits, but also of lode gold deposits.