The noble metal distribution in the black shales of the Degdekan gold deposit in Northeast Russia |
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| Authors: | A I Khanchuk L P Plyusnina E M Nikitenko T V Kuzmina N N Barinov |
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| Institution: | 1.Far East Geological Institute, Far East Branch,Russian Academy of Sciences,Vladivostok,Russia;2.OAO Matrosov Mine,Magadan,Russia |
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| Abstract: | The mineral and chemical composition of the carbon-bearing rocks of the Late Permian Pionerskaya Formation containing the
Degdekan gold deposit has been studied. The bulk contents of Au, Ag, Pt, and Pd in the black shales and their light, sulfide,
and electromagnetic fractions were determined by electrothermal atomization. The mineral composition and the phase analysis
of the rocks were studied using a scanning electron microscope. Gold is present as fine xenomorphic grains of high fineness
with an Fe admixture of up to 4 at %, as well as intergrowths of kustelite and electrum. The Au and Pt contents in the black
shales and ores vary in a wide range (g/t): Au 0.01–13.12, Pt 0.001–1.34. The highest Au contents (up to 1748 g/t) were noted
in the sulfide fraction. The Pt-bearing phases were not found, whereas a Pt content of about 0.61 wt % was determined using
an electron microscope in a carbonaceous matrix. The initial rocks have a steady and low Pt content (less than 0.007 g/t).
A stable even Au distribution in the studied rocks was established within 1.14–2.46 g/t. The chemical analysis of the soluble
fraction of the carbonaceous matter extracted from the black shales showed the presence of Au 0.375, Ag 3.68, Pt 0.147, and
Pd 0.052 g/t. It has been concluded that the carbon-bearing rocks of the Pionerskaya Formation play a resource role in the
accumulation of noble metals, whereas economic concentrations of the latters are formed in the course of the superimposed
metamorphic-hydrothermal processes. |
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