Innerelv member: late Precambrian marine shelf deposit, East Finnmark.

Abstract

The Innerelv Member forms part of the succession between the late Precambrian tillites and the Lower Cambrian rocks in eastern Finnmark and it has a considerable lateral extent. It is about 300 m thick in the Tanafjord area but thins to 70 m to the west, at the head of Laksefjord. It can probably be correlated with Member II of the Dividal Group at Halkkavarre 60 km to the southwest (Føyn 1967). Apart from a complex basal zone the Member can be divided into six facies, the first five of which form a gradiation series from mudstones with siltstone laminae through thinly bedded, parallel sided siltstones and very fine sandstones to lenses of intercalated sandstone, siltstone, and mudstone. These five facies represent a series of environments of gradually increasing energy and it is suggested that this energy was related to depth and proximity to a shoreline. The siltstones and sandstones were possibly deposited by currents generated by the backflow of storm surges from an otherwise low energy coastline.