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Russian Geology and Geophysics

2014 year, number 10

RELATIONSHIP OF ANTIMONY WITH GOLD MINERALIZATION IN THE ORE DISTRICTS OF EASTERN KAZAKHSTAN

K.R. Kovalev1, Yu.A. Kalinin2, E.A. Naumov2, M.K. Myagkaya1
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Sb mineralization, disseminated gold-sulfide ores, carbonaceous rocks, Eastern Kazakhstan

Abstract

In Eastern Kazakhstan, Sb mineralization is the most widespread in the Irtysh and Bakyrchik ore districts of the West Kalba gold-bearing belt. It is spatially related to disseminated gold-sulfide ores at some deposits and is structurally and spatially isolated at others. The disseminated gold-sulfide mineralization is localized in Carboniferous carbonaceous-terrigenous carbonate rocks. It is marked off by zones of dynamic metamorphism and foliation and is characterized by the ribbon-like-lenticular morphology of ore deposits. Later Sb (predominantly, quartz-antimonite) mineralization is formed in the extension setting as brecciated/veined ores. In combination with gold-sulfide ores, Sb mineralization is more diverse. For example, microparageneses with berthierite, native Sb, aurostibite, ullmannite, jamesonite, and tetrahedrite coexist with pocket-vein quartz-carbonate-antimonite mineralization in the gold-sulfide ores of the Suzdal’skoe deposit. Also, Sb-containing minerals such as arsenopyrite and pyrite are observed. Two temperature regimes of mineralization are established here: 418–300 °C for gold-polysulfide mineralization and 280200 C for later Sb mineralization. The isotopic composition of antimonite sulfur at the Suzdalskoe, Zherek, Zhanan, Bakyrchik, and Dalnii 1 deposits shows close values within the interval δ34S of 3.8 to +2.5 ‰, suggesting its great-depth origin. No visible gold is found in the antimonite of the quartz-antimonite veins, but atomic-absorption analysis reveals few ppm or more gold. Point X-ray analysis indicates possible presence of the so-called “invisible” gold. Microstructural observations, temporal relationships of the parageneses, and studies of gas-liquid inclusions at the Suzdalskoe deposit permit assigning Sb mineralization to the second productive gold-polysulfide stage of the ore deposition. The late antimonite stage of mineralization is separated from the gold-polysulfide stage by 7 Myr long intramineralization tectonic shifts. Gold-polysulfide mineralization (248.3 ± 3.4 Ma) was synchronous with Triassic tectonomagmatic activity.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.09.003