Geochemistry of highly aluminiferous Vendian-Cambrian sediments of the Tunka Bald Mountains, East Sayan

This paper presents comprehensive geochemical characteristics of highly aluminiferous schists discovered in the Tunka Bald Mountains and associated with the Vendian-Cambrian cover of the Tuva-Mongolian Microcontinent. The Al2O3 content varies within a wide range, the maximum being up to 36.11 wt. %. A specific feature of the geochemical composition of these rocks is the simultaneously high contents of Cr (up to 1400 ppm), V (up to 2700 ppm), and Zr (up to 800 ppm). The origin has been interpreted, and the conditions in which the highly aluminiferous rocks formed have been considered. Based on geochemical data, it is assumed that the main origin could be weathering crusts formed after ultramafic and mafic rocks, with a felsic source playing a secondary role.