Sourceland of terrigenous material during the formation of aquatic deposits of the Keltmin burial canyon (based on the study of chromespinelides)

The typomorphic features and chemical composition of chromespinelides from the Quaternary aquatic sediments of the Keltmin Buried Canyon in the southeastern Komi Republic have been studied for the first time. It has been established that the chromespinelides are characterized by predominantly rounded and octahedral grain shapes with pronounced traces of mechanical surface wear and signs of corrosion. Chemically, the grain cores are composed predominantly of aluminochromites, chrompicotites, chromites, and subferrialuminochromites, while the outer rims are composed of more ferrous varieties (subferrichromites and subalumoferrichromites), indicating postmagmatic alteration of the chromespinelides. Microinclusions of chlorites, plagioclases, amphiboles, and pyroxenes have been detected. The study results indicate a connection between chromespinels and ultramafic rocks of the Alpine-type massifs of the Polar Urals. Their transport and redeposition in the aquatic formations of the Keltmin Trough are largely related to the exaration activity of the glacier. The obtained data are consistent with our previously published study of the composition of aquatic sediments of the buried canyon, which indicate the involvement of Ural igneous and metamorphic complexes in the formation of these sediments, as well as the possibility of the supply of detrital material to the Keltmin Trough from ophiolite association rocks of ultramafic massifs of the Polar and Subpolar Urals.