Silicate, Fe-Oxide, and Au–Cu–Ag Microspherules in Ores and Pyroclastic Rocks of the Kostenga Iron Deposit, in the Far East of Russia
Н. В. Бердников, В. Г. Невструев, Pavel Kepezhinskas, В. О. Крутикова, N. S. Konovalova, И. А. Астапов
Abstract
Numerous silicate, Fe-oxide, and Cu–Au–Ag microspherules are found in Fe ores and pyroclastic rocks of the Kostenga deposit, Lesser Khingan (Far East of Russia). The silicate spherules contain immiscible Fe and Si glasses, vapor voids, and mineral inclusions. The Fe-oxide spherules host magnetite with a small amount of ilmenite and Fe-rich silicate glass. The Cu–Au–Ag spherules contain inclusions with dominant CuO in their composition. These microspherules are considered to form due to rapid uplift and degassing of liquation-differentiated ore-silicate melts. The possible volcanic formation of ores and precious metal mineralization is discussed for these types of the deposits.