COCCOID MICROPHYTOFOSSIL FINDS FROM THE LOWER PROTEROZOIC METAMORPHOSED CHERTS OF THE USSR

Abstract

While studying the supracrustal Pechenga complex, we found Lower Proterozoic microfossils in our petrographic thin sections. The rocks containing these organic remains make up a two-meter unit of microquartzite, altered in the greenschist facies of regional metamorphism of primary cherty deposits, and occur within in lava metabasite of the middle of the Upper Kolasiok subsuite. Given new data on the isotope age of the under- and overlying rocks, the primary cherty rocks were deposited about 2.0 bln yrs ago. We found numerous groupings of small spheroidal cells in 18 thin sections from three rock samples. We found three varieties of colonies, differing in structure of the colonies and morphology of the cells. Our microfossils are chroococcic organisms.