Noble Metals in Rocks of the Sarma Group: Phase Composition and Element Associations

The paper presents data on noble-metal mineralization in carbon-bearing rocks of the Sarma Group in the southern flank of the Baikal inlier of the Siberian craton basement. The phase composition of the accessory ore minerals (pyrite, arsenopyrite, microinclusions of native Ni, Sn, Zn, Cu, Fe–Ni and Ni–Fe–Ti composite compounds, Cu and Pb sulfides, rutile, monazite, zircon, and barite) were determined by X-ray microanalysis. Gold, silver, and all elements of the platinum group were determined by scintillation arc atomic emission spectrometry in rock samples from the Ilikta and Hulurtui formations. These elements occur as particles of native noble metals, their intermetallic compounds, sulfides, arsenides, selenides, and sulfosalts. Noble-metal mineralization in the Hulurtui and Ilikta formations of the Sarma Group is proved to be genetically related to tectono-metasomatic processes that affected the primary metasedimentary rocks.