Hyolithus-sonens basale lag i Vest-Finnmark.

Abstract

The basal layers of the \"Hyolithus-zone\" in western Finnmark: The \"Hyolithus- zone\" is a term which has been attached to the autochtonous Cambrian substratum of the Caledonides which can be followed from Laksefjord in Finnmark southwards through Finland and northern Sweden. From Finnmark it has been described by O. Holtedahl (1918 and 1953). It is a characteristic formation, consisting of silty shales and sandstones. The geological age has been determined as lower Cambrian on the account of the sparse fossils found (platysolenites). The formation consists of the following members from below: 1. The basal quartzitic and\/or conglomeratic bed. Thickness to the east about 5 metres (Holtedahl), to the west less than 1 metre. 2. The lower shale, consisting of green and reddish (silty) shale, interbedded with thin sandstone layers. Thickness to the east 80 metres, to the west 20- 30 metres. 3. The sandstone beds, consisting of thick sandstone layers of pale greenish and reddish colours. Thickness to the east 17 metres, to the west 4 metres. 4. The upper shale, very similar to the lower shale. Thickness varable because of the different position of the thrust plane above. All these members are present in every section, with the possible exception of the basal bed locality 3 (see fig. 1).