The paper presents results of research into the conditions of formation of ores in the poorly studied Algama ore cluster
(Bodorono deposit and Dyvok ore occurrence) located at the junction of the Aldan Shield and the Stanovoi area. We have established that
Bi and Se minerals (bismuthinite, lillianite, native bismuth, tellurobismuthite, tetradymite, hedleyite, pilsenite, and laitakarite) are present
in the ores of the Bodorono deposit. Two successive productive stages of mineral formation have been distinguished: Au–polymetallic and
Au–Bi–Te. The corresponding minerals are products of the evolution of a hydrothermal system, during which a gradual decrease in fluid
temperature (from 300 to 145 °C) and salinity (from 5 to 1.9 wt.% NaCl equiv.) took place. The fineness of native gold gradually increases
from early (~840‰) to late (~940‰) stages and changes in passing from simple sulfides to sulfosalts. The evolution of the ore system is
accompanied by a change in the composition of the vapor phase of fluid inclusions from CH4–CO2 to CO2 with an impurity of N2 and CH4.
The results of 40Ar/39Ar dating of pre-ore metasomatites point to ore-forming processes at the Bodorono deposit ca. 150 ± 1.8 Ma. Analysis
of the isotopic composition of lead in galena shows the leading role of the ancient crustal source of ore matter. The calculated isotopic
composition of oxygen (δ18OH2O) in ore-bearing quartz varies from 1.0 to 7.3‰, which corresponds to an aqueous fluid of a mixed source.
The Dyvok ore occurrence differs from the Bodorono deposit in the mineral composition of ores and the physicochemical parameters of
ore formation. Four mineral stages have been established within the ore occurrence: gold–arsenopyrite–pyrite–quartz, pyrite–chalcopyrite–
sphalerite, quartz–boulangerite, and telluride. The telluride stage is represented by hessite, altaite, volynskite, merenskyite, melonite, and
rucklidgeite. Gold-bearing mineralization formed from a fluid of medium salinity (0.9–9.2 wt.% NaCl equiv.) with a predominance of CO2
and an impurity of CH4 in the vapor phase at moderate temperatures (310–360 °C). The calculated values of δ34S and δ18O varied from 2.2
to 3.0‰ and from 0.6 to 12.0‰, respectively. The 40Ar/39Ar age of gold mineralization is 124.0 ± 1.5 Ma, which corresponds to the stage
of tectonomagmatic activity in the Aldan Shield.