Columnar stromatolites of the terminal Precambrian Porsanger Dolomite and Grasdal Formation of Finnmark, north Norway

Nine horizons of algal stromatolites have been recognized in the Porsanger Dolomite: one new group, Gaaradakia, and five new forms, Linella akkaniella, Eleonora laponica, Gaaradakia jacutophytonica, Linella trollina and Inzeria sinopivarra are described. In the Grasdal Formation, lithostratigraphic
correlative of the Porsanger Dolomite, three horizons of algal stromatolites are recognized and one new form described, Minjaria tana. The stromatolite assemblage of both formations is in general suggestive of a late Upper Riphean/Vendian age. However, the Porsanger Dolomite and Grasdal Formation have no stromatolite forms in common and it is tentatively concluded that the Grasdal Formation is slightly younger than the Porsanger Dolomite. The Porsanger Dolomite contains some stromatolite forms similar to those of the Eleonore Bay Group of East Greenland and the upper Middle Hecla Hoek of Spitsbergen. Affinities with Late Precambrian stromatolite assemblages of the USSR are limited.