Chemical Features of Rare-Earths Accessory Minerals in the Lower–Middle Cambrian Terrigenous Rocks from the Argun Series of the Northwestern Part of the Argun Superterrane as Indicators of the Sources

The paper presents the results of the chemical study of rare-earth accessory minerals of the Lower–Middle Cambrian terrigenous rocks of the Bystraya Formation and the Ernichny Unit of the Argun Series of the Argun Superterrane. The chemical analysis of monazite, xenotime and rhabdophane was performed using analytical JSM-6390LV JEOL and SIGMA electron microscopes (SEM). The siltstone of the Bystraya Formation contains monazite-(Ce) and rhabdophane, while the sandstone of the Ernichny Unit contains monazite-(Ce) and monazite-(Nd), xenotime and rhabdophane. The chemical composition of rare-earth minerals in terrigenous rocks from the Argun Series suggests that the felsic igneous and metamorphic rocks in a source area. These data, together with the results of previously performed geochemical and isotopic (Sm-Nd, U-Pb (LA-ICP-MS)) studies, the main sources of light and heavy rare earth element phosphates were the Neoproterozoic granitoids of the Urtui and Urulyungui complexes of the Argun Superterrane.