Инд. авторы:	Pavlova G.G., Borovikov A.A.
Заглавие:	Silver-antimony deposits of Central Asia: Physico-chemical model of formation and sources of mineralisation
Библ. ссылка:	Pavlova G.G., Borovikov A.A. Silver-antimony deposits of Central Asia: Physico-chemical model of formation and sources of mineralisation // Australian Journal of Earth Sciences. - 2010. - Vol.57. - Iss. 6. - P.755-775. - ISSN 0812-0099. - EISSN 1440-0952.
Внешние системы:	DOI: 10.1080/08120091003736540; РИНЦ: 15319414; SCOPUS: 2-s2.0-77955640550;
Реферат:	eng: Questions on the origin of Ag-Sb deposits are considered for several large economic ore districts in Central Asia: southeast Pamir (Tajikistan), Talas in northern Tien Shan (Kyrgyzstan), southeast Altai and northwest Mongolia, and Verkhoyansk province (Yakutia). The Ag-Sb mineralisation of Central Asia is spatially and temporally associated with alkaline mafic magmatism, and occasionally with coeval granitoid magmatism. Ag-Sb deposits have close spatial and temporal relationships with granitoid and alkaline mafic magmatism. The Ag-Sb deposits were formed in the temperature range 50-280°C, from Ag-specific reduced two-phase hydrothermal fluids containing a highly concentrated chloride solution (NaCl > FeCl2 > CaCl2 > KCl > MnCl2) and a high-density CO2 + CH4 ± N2 gaseous phase. Fluid salinities range widely from 40 to 0.1 wt% NaCl equiv. Geochemical specialisation of Ag-Sb ore is caused by chemical features of chloride brines enriched in Ag, Sb, Pb and Cu, with a relatively low Au content (≤10-6 mol/kg) within a pH of 3.5-4. The highest temperatures, concentrations of solutions and ore elements in the ore fluids were found in early quartz of siderite-tetrahedrite veins from below-ore level of the ore-forming system. Vertical zonation of the Ag-Sb mineralisation is caused by precipitation of different mineral associations from the same solution with temperatures decreasing towards the upper parts of the system. Sufficient vertical range of mineralisation (600-800 m) and relatively low Ag contents in the ore (300-600 ppm) result from the temperature decrease and absence of geochemical barriers. Higher temperature gradient and dilution of magmatogenic fluid with meteoric water was a geochemical barrier for the Ag-rich ore formation in a narrow (about 400 m) main ore deposition zone. Lateral zonation of Ag-Sb mineralisation is related to a staged development of the ore-forming process and deposition of different stage mineral associations at the beginning and end of the hydrothermal process. The Ag-Sb deposits are polygenic in terms of sources of ore elements and ore-forming fluids. Ore elements may have been inherited from magmatic and terrigenous host-rocks of different ages. Temporal correlation of the Ag-Sb mineralisation with alkaline mafic magmatism, He isotope composition and Hg contents in the ores confirm participation of a mantle source in the formation of the Ag-Sb deposits. © 2010 Geological Society of Australia.
Ключевые слова:	Tien Shan; Sakha; Russian Federation; Pamirs; Altai Mountains; temperature gradient; silver; ore-forming fluid; mineralization; mineral deposit; mantle source; Verkhoyansk; mafic rock; hydrothermal fluid; host rock; granitoid; antimony; alkaline rock; Silverantimony deposits; Mafic magmatism; Hydrothermal fluids; Granitoid magmatism; Central asia; magmatism;
Издано:	2010
Физ. характеристика:	с.755-775