Physicochemical Modeling of Hydrothermal Mineralization Processes at Ni–Co–As (±U–Ag), Co–S–As (±Au–W), and Cu–Co–As (±Sb–Ag) Deposits

Abstract

The paper reports generalized investigation data on the composition of metal-bearing fluids at hydrothermal cobalt deposits, which formed in different geodynamic settings during the development of alkali and alkali-basic intrusions and dikes. To determine the physicochemical parameters of ore deposition from fluid inclusions in minerals, both traditional and new instrumental thermobarogeochemical methods were used: thermometry, cryometry, and Raman spectroscopy; the concentrations of ore- and rock-forming elements in individual fluid inclusions were evaluated by LA-ICP-MS. The results served as the basis for a study focused on thermodynamic modeling of joint transport and deposition of Co, Ni, Cu, Fe, Mg, Ca, Ag, Au, Bi, U, Pt, and Pd; the number of equilibrium states of the hydrothermal system similar in composition to the natural ore-forming fluids was also calculated. The physicochemical factors of native Au, Ag, Pt, and Pd in the ores at such deposits were revealed. These data can be used to develop correct genetic models for the ore-forming systems of the cobalt deposits proper and to solve the problem of searching for them.