Late Precambrian and Cambro-Ordovician sedimentation in East Finnmark.

• Main Authors: Hobday, D.A., Reading, H.G., Banks, N. L., Edwards, M.B., Geddes, W.P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1971
• Subjects: GLASIALGEOLOGI; PETROGRAFI; STRATIGRAFI; SEDIMENTOLOGI; FACIES; Porsanger; Vadsø; Vestertana; Lebesby; Langfjorden; Finnmark; Tana; Varangerfjord; Varangerfjord*
• Online Access: https://hdl.handle.net/11250/2674937

The presence of two closely spaced tillite formations within the Precambrian and Cambro-Ordovician sediments of eastern Finnmark permits subdivision into pre-glacial and post-glacial regimes. On the northern side of Varangerfjord the preglacial \"Older Sandstone Series\" of Precambrian age consists of six lithological members, which collectively represent transgressive-regressive cycles. Within each cycle shallow marine siltstones are overlain by coarser sediments of intertidal, estuarine and fluvial origin. Two distinct sedimentary sources are suggested by palaeocurrent and petrographic evidence. Influx from a westerly direction tended to dominate over a volumetrically less significant source of immature detritus from the east or southeast. The \"Older Sandstone Series\" is overlain with slight angular unconformity by the glacially dominated sediments of the lower part of the Vestertana Group. The two tillite formations consists of both continental and marine glacial deposits, with marine influence increasing northward. The interglacial Nyborg Formation consists largely of turbidite sandstones, with a transgressive sequence at the base and a regressive sequence at the top. All of the sediments of glacially dominated regime appear to have been derived from the south. 35121