Correlation of proterozoic sediments of western and Central Africa and South America based upon radiochronological and palaeontological data

Abstract

Abstract Nearly 70 new RbSr isochron ages and many KAr conventional ages have been determined between 1975 and 1980 on Proterozoic sedimentary or metasedimentary sequences in western and Central Africa and South America. Some stratigraphic results have been established: 1. (1) five formations have been dated of the Lower Proterozoic; 2. (2) a long sedimentation gap occurs, mainly in western African and in some regions of Central Africa and South America between nearly 1600 and 1100 Ma; 3. (3) the upper Riphean assemblages of stromatolites have been dated and compared to those of the Eurasian craton; 4. (4) two main glacial events have been dated, the first one placed at ca. 950 Ma, the second one during the Vendian, at ca. 650-620 Ma; 5. (5) it can be stated that, when applied to Precambrian sequences, all stratigraphic methods must be used together.