A Unique Ore-Placer Cluster with High-Hg Gold Mineralization in the Amur Region (Russia)

摘要

This work presents the geological structure and a description of gold-ore manifestations and gold placers in the Un'ya-Bom ore-placer cluster of the Amur gold-bearing province. The host rocks are Late Paleozoic and Mesozoic black-shale formations. Intrusive formations are rare. The sublatitudinal Un'ya thrust fault, along which Paleozoic sandstones overlap Mesozoic flyschoid deposits, is regarded as an orecontrolling structure. Gold-quartz and low-sulfide ores are confined to quartz-vein zones. Ore minerals are arsenopyrite, scheelite, ferberite, galena, and native gold. Gold-ore manifestations and placers contain highHg native gold. The high Hg content in native gold is explained by the occurrence of the eroded frontal part of the gold-ore pipe in the ore cluster, a source of native gold.