GEOCHEMISTRY OF URANIUM IN VENDIAN-CAMBRI AN PHOSPHORITES

Control analyses were performed to check the data, both published and unpublished before, on low uranium content in ancient (Vendian-Cambria n) phosphorites of four largest basins - Khubsugul in Mongolia, Karata u in Kazakhstan, Yangtze in China and Volta syneclise in the West Afri ca. The uranium content was confirmed to be about 10 ppm. The low uran ium content was not caused by any postsedimentational processes, hyper - or hypogeneous, but evidences for primary uranium concentration. It might be explained by the peculiar ''in situ'' character of the ancien t phosphorites. It means that accumulation f uranium in the apatite la ttice due to the Altschuler's of ''the regenerative capture'' can be i mplied only for pelletal phosphorites formed after repeated transporta tion and redeposition of phosphate pelles but not for structurelles be dded ''in situ'' phosphorites.