Native Gold of the Chochimbal Ore-Placer Cluster (West Verkhoyansk)

Abstract

Chochimbal ore-placer cluster is a part of the West Verkhoyansk metallogenic zone, which is characterized by large stratified silver and vein-type gold-silver deposits and ore occurrences. The goal of this work was to study mineralogic-geochemical features of placer gold from the Chochimbal Creek basin in order to identify, as a result of what sources, endogenetic mineralization or hypergenesis zones, placer gold content of the studied area was formed. Alluvial gold with total weight of 11,8 g from eluvial-talus and alluvial deposits of the Chochimbla Creek and its tributaries is studied. Wide range of known mineralogic-geochemical methods of analyses was used in studies of typomorphic features of placer gold. Results of analysis of placer gold on granulometry, morphology (shape, surface, degree of roundness), chemical composition, internal structure and microinclusions are shown in the article. Obtained results of studies of placer gold mineralogy and its comparison with available data on placer gold of the Chochimbal ore-placer cluster allowed us to conclude that, auriferous placers of the Cochimbal Creek basin were formed due to destruction of neighboring ore sources, confined to arched portion of the Imtandzhin anticlinal, where maximum depth of erosional truncation of ore bodies is observed. Placer and ore gold of the ore-placer cluster have similar mineralogic features. Identified typomorphic features of placer gold allows us to judge that, placers were formed mainly due to ore occurrences of gold-quartz formation, and in a less degree due to gold-sulfide and gold-silver formations.