Processes and Products of Large, Late Precambrian Sandy Rivers in Northern Norway

  1. M. Marzo and
  2. C. Puigdefábregas
  1. S.-L. Røe1 and
  2. M. Hermansen2

Published Online: 14 APR 2009

DOI: 10.1002/9781444303995.ch12

Alluvial Sedimentation

Alluvial Sedimentation

How to Cite

Røe, S.-L. and Hermansen, M. (1993) Processes and Products of Large, Late Precambrian Sandy Rivers in Northern Norway, in Alluvial Sedimentation (eds M. Marzo and C. Puigdefábregas), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303995.ch12

Editor Information

  1. Barcelona, Spain

Author Information

  1. 1

    Geological Institute, Dept A, University of Bergen, 5007 Bergen, Norway

  2. 2

    Norsk Hydro A/S, PO Box 200, 1321 Stabekk, Norway

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 16 SEP 1993

ISBN Information

Print ISBN: 9780632035458

Online ISBN: 9781444303995

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Keywords:

  • unidirectional palaeocurrents;
  • absence of cyclicity, vertical sedimentation time-trends;
  • dominance of fine-grained sandstone;
  • dominance of medium- and large-scale cross-sets;
  • In-traformational conglomerates occur locally;
  • sandstone bodies between channel erosion surfaces

Summary

Late Precambrian fluvial sandstones of the Fugleberget Formation and Hestman Member, northern Norway are dominated by sheet-like sandstone bodies (0.7–6 m thick, with exposed length of up to 200 m). The sandstone bodies, of mainly bar origin, consist of fine-grained sandstone and are subdivided into three types. Type A sandstone bodies (simple bars) comprise either solitary sets of large-scale, concave-up and sigmoidal-shaped cross-strata, or low-angle inclined to horizontal planarstrata, or they show a combination of the cross- and planar-stratified facies. Type B sandstone bodies (mainly compound bars) are composed of superimposed or downward-climbing cross-sets. Type C sandstone bodies (composite bars) show an upstream or downstream transition from large, solitary cross- or planar-stratified sets to cosets of medium-scale cross-sets.

The simple to composite bars of the sheet-sandstone bodies are interpreted to represent short-term depositional events, possibly within one flood cycle. Over a longer time span (one to several flood cycles) they probably grew or amalgamated into macroforms several times larger in downflow and lateral dimensions than the component bars. High discharge variability (absence of vegetated source terrains), high sediment load and transport rates (current velocities much higher than critical erosion velocity) and easily erodible banks contributed to the formation of very wide, unstable, low-sinuosity rivers with a mainly braided pattern during intermediate- and low-flow stages.