The Porsanger Sandstone Formation and subjacent rocks in the Lakselv District, Finnmark, Northern Norway.

Abstract

The Porsanger Sandstone Formation forms an imbricated thrust mass lying between the Precambrian Basement Complex to the south-east and an allochthonous nappe of \"Caledonian\" metamorphic rocks to the north-west. The Porsanger Sandstone Formation is separeted form the basement by a thin sequence ofautochthonous \"Hyolithes Zone\" sediments. The feldspathic sandstones and shales of the \"Hyolithes Zone\" rest unconformably upon a weathered surface of Precambrian gneisses. The \"Hyolithes Zone\" lies in the north-west limb of a north-easterly striking anticline which developed during post-Lower Cambrian time, folding the basement Complex and the \"Hyolithes Zone\" a single unit. The Porsanger Sandstone Formation was thrust over this structure during the Caledonian orogeny. In addition, the Porsanger Sandstone Formation was folded asymmetrically about northerly axes and the sequence is repeated by a number of thrust faults which dip to the west at a low angle. The Porsanger Sandstone Formation is subdivided into four lithostratigraphical units: l. Skallenes Sandstone, 2. Bjørnnes Sandstone, 3. Valddak Sandstone, 4. Gorssavatn Shales. The age of the Porsanger Sandstone Formation is uncertain, but it is probably Precambrian. No fossils were found in the formation.