GEOCHEMISTRY OF QUARTZITES AND QUARTZITOS CHISTS OF THE OLKHON REGION(WESTERN BAIKAL AREA)

The fourth in a succession of papers on the geochemistry of metamorphi c Olkon sequence deals with quartzitic rocks. Their layers intercalati ng with marbles and basic schists hold a regular position in thes esti ons of the Olkhon and Anga sequences. The characteristic feature of th e Olkhon quartzitic rocks is high content of Cr and V, Cr-V spinels, t ourmalines, micas, oxides have been found there. A new mineral - olkho nskite (Cr-schreyerite) was found amond them. Besides, they are enrich ed in C, S, Mo, Ag, Sr and, which ale typical of black shales, The qua rtzites of Anga suite are rich in Mn up to the gondite formation appea rance, as well as P, F and Ba - the characteristic elements of mangane se concretions. The geochemical distinctions that were mentioned previ ously for other metasediments and metavolcanites testify that the form atin of the Olkhon sequence' protolith was in reduced conditions in a marginal sea, while that of Anga suite - in oxidized environment on th e slopes of a mature island ars. Analyses of rocks and minerals are gi ven.