The Khokhoy Deposit Is a New Carlin-Type Gold-Bearing Object (the Aldan Shield)
摘要
To the west of the unique gold-mining Central Aldan ore district at the Khokhoy deposit of the Verkhneamginsky district, gold mineralization has been identified for the first time in terms of regional position, structural, morphological, and mineralogical–geochemical parameters comparable to its global analogue, the Carlin type. The deposit is located on the northern margin of the Precambrian Aldan shield in the deep Amga fault zone at the junction of two large structural units: the Olekminskaya granite-greenstone area (Olekminsky craton) and the Aldanskaya granulite-gneiss area (mobile belt). The mineralization is represented by sandy loam-clay-clastic karst formations developed on the tectonized contact of Lower Cambrian carbonate and Lower Jurassic terrigenous sedimentary rocks. Ore-bearing sublongitudinal steeply falling discontinuous faults are accompanied by Cretaceous dikes of subalkaline rocks. The friable supergenic formations consist of quartz, muscovite, clay minerals (illite, clinochlore, Fe-clinochlore, kaolinite), lepidocrocite, carbonates, barite, fluorite, goethite, jarosite, and hematite. The primary ores were preserved in the form of fragments/relics of jasperoids—pyrite-adularia-quartz metasomatites formed as a result of silicic-potassic metasomatism of carbonate rocks. Jasperoids carry low-temperature mineralization, represented by fine-grained quartz, chalcedony, adularia, sericite, calcite, barite, fluorite, illite, hollandite, pyrite, minerals of thallium, antimony, arsenic, tellurium, and mercury. The geochemical association of elements is Au–As–Sb–Tl–Te–Hg. Finely dispersed native gold of primary ores with a size of no more than 0.005 mm is found in oxidized pyrite enriched with Sb, As, and Hg, as well as in association with minerals of thallium and mercury. In friable karst formations, the residual gold was released and enlarged to 0.1–0.5 mm. High-grade supergenic gold is characterized by a spongy structure and an admixture of Hg. A new mineral, thallium tellurate Tl2TeO6—amgaite—has been discovered in the ores. The substantiation of the highly productive Carlin type of gold mineralization of the Khokhoy deposit will serve as the basis for the revision and revaluation of the Kuranakh type in the area of the Aldan shield.