TY - JOUR

T1 - Alluvial-Placer Gold of Northwestern Salair

T2 - Composition, Types, and Mineral Microinclusions

AU - Nevolko, P. A.

AU - Kolpakov, V. V.

AU - Nesterenko, G.

AU - Fominykh, P. A.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - On the territory of the Egor’evsk district, 3500 results of probe microanalyses of surface gold particles taken from 17 placers, weathering crusts, and orebodies were processed and summarized. High-fineness and mercury-containing gold is predominantly found within mother lodes and placers, and medium- and low-fineness gold is distributed in subordinate and dramatically subordinate quantities, especially in the placers. A unique feature of the gold composition, rarely occurring in other districts, is the constant and commonly simultaneous presence of mercury and copper impurities. Analysis of Ag, Hg, and Cu content variations has enabled us to identify five main grades of gold. The mother lodes of the predominant gold grades are metasomatites with beresite and listwaenite compositions, which are developed primarily after lower Cambrian volcanoterrigenous-carbonate rocks and ore-bearing mafic dikes. Mercury-containing gold is characteristic of beresites, but copper-bearing gold is typical of listwaenites. The relationship between corresponding grades of surface and ore gold is confirmed by the presence of microinclusions in the gold grains. Nonconformity between the content of gold from mother loads, weathering crusts, and placers is explained by the losses of Hg and Ag impurities by endogenous gold under subsurface hypergene conditions. Identification of mineral-geochemical properties of surface gold is of exceptional practical importance in ore-grade gold mineralization prediction.

AB - On the territory of the Egor’evsk district, 3500 results of probe microanalyses of surface gold particles taken from 17 placers, weathering crusts, and orebodies were processed and summarized. High-fineness and mercury-containing gold is predominantly found within mother lodes and placers, and medium- and low-fineness gold is distributed in subordinate and dramatically subordinate quantities, especially in the placers. A unique feature of the gold composition, rarely occurring in other districts, is the constant and commonly simultaneous presence of mercury and copper impurities. Analysis of Ag, Hg, and Cu content variations has enabled us to identify five main grades of gold. The mother lodes of the predominant gold grades are metasomatites with beresite and listwaenite compositions, which are developed primarily after lower Cambrian volcanoterrigenous-carbonate rocks and ore-bearing mafic dikes. Mercury-containing gold is characteristic of beresites, but copper-bearing gold is typical of listwaenites. The relationship between corresponding grades of surface and ore gold is confirmed by the presence of microinclusions in the gold grains. Nonconformity between the content of gold from mother loads, weathering crusts, and placers is explained by the losses of Hg and Ag impurities by endogenous gold under subsurface hypergene conditions. Identification of mineral-geochemical properties of surface gold is of exceptional practical importance in ore-grade gold mineralization prediction.

KW - alluvial placers

KW - gold

KW - mother lodes

KW - gold fineness

KW - impurity elements

KW - grades/types of gold

KW - DEPOSITS

KW - DISTRICT

KW - CANADA

KW - GRAINS

KW - LODE

KW - Grades/types of gold

KW - Gold

KW - Gold fineness

KW - Alluvial placers

KW - Impurity elements

KW - Mother lodes

UR - http://www.scopus.com/inward/record.url?scp=85079478489&partnerID=8YFLogxK

U2 - 10.15372/RGG2019005

DO - 10.15372/RGG2019005

M3 - Article

VL - 60

SP - 67

EP - 85

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 1

ER -