Abstract

—We present data on the mineral and geochemical compositions of metasedimentary Mn-bearing rocks of the Itantsa Formation of the Ikat terrane. According to the mineral composition, the studied quartz–spessartine rocks of the formation are referred to as gondites. The main Mn-concentrating minerals are garnet, pyrophanite, and Mn-ilmenite, and the secondary ones are rhodonite and Mn-amphibole. Two Mn-bearing objects of the Itantsa Formation (Usutai deposit and Almarnatol occurrence) show differences in chemical and mineral compositions, related to different sources of their material, different distances from the mouth of a hydrothermal vent, and different degrees of postsedimentary alteration. The Mn-bearing deposits of the formation accumulated in a sedimentary basin in the immediate vicinity of continental provenance areas in the Late Neoproterozoic (Ediacaran), under synchronous volcanic activity.

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