| UDC 553.411’48(571.65) |
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Mineralogy and Conditions of Gold-Bearing Cobalt Ore Formation at the Obkhod Deposit (North-East of Russia) |
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| © 2015 E. E. Kolova, M. A. Malinovskiy |
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| North-East Interdisciplinary Scientific Research Institute n. a. N. A. Shilo, FEB RAS, Magadan |
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| E-mail: ;
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| Mineralogical, geochemical, and termobarogeochemical research of cobalt ores at the Obkhod Deposit,
localized in Jurassic sediments in the exocontact of the Early Cretaceous amphibole-biotite
granitoid massif, have been carried out. The main ore minerals are described. Specifi c geochemistry
of the ores – presence of gold, higher concentrations of Cu, Ni, Bi, Te in the ores. The mineralization
is shown to have formed in the presence of CO2 in the temperature range of 436 through 202°C
from medium-concentrated (22,0–0,53 wt.% Eq. NaCl) hydrothermal solutions with densities varying
from 0.7 to 1.0 g/cm3 and the predominant ions of Na, Fe, Mg, Cl (Tevt. = -34 ... -22°C). On
the basis of mineral paragenesis, the mineral formation staging has been schematized. The Raman
spectroscopy of fl uid inclusion subsidiary phases identifi ed ferropirosmalite. The combination of
these signs permitted to brought about the question of referring the Obkhod Deposit to the Co-Cu-
Au-type deposits localized in metasedimentary rocks. |
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| Keywords: Left-Seymkan granitoid massif, Co-Cu-Au type, cobaltite, thermobarogeochemistry. |
| Full text [In Russian] |
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