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Cross‐strata and bedforms of probable transitional dune to upper‐stage plane‐bed origin from a Late Precambrian fluvial sandstone, northern Norway.

 

作者: SIGNE‐LINE RØE,  

 

期刊: Sedimentology  (WILEY Available online 1987)
卷期: Volume 34, issue 1  

页码: 89-101

 

ISSN:0037-0746

 

年代: 1987

 

DOI:10.1111/j.1365-3091.1987.tb00562.x

 

出版商: Blackwell Publishing Ltd

 

数据来源: WILEY

 

摘要:

ABSTRACTA Late Precambrian fluvial sandstone sequence in northern Norway is dominated by large‐scale cross‐sets that show eitherlenticularortabulargeometries in the streamwise sections. The lenticular sets interdigitate and in places show nearly symmetrical formsets. The tabular sets are in places solitary, but are mainly grouped in cosets. In both cross‐set types, the cross‐strata range fromconcave‐uptosigmoidalin shape, with the latter variety comprising subhorizontal to gently inclined topset strata (with parting lineation) that merge uninterruptedly downflow into the steeper (10–2°) foresets. Within the cross‐sets the geometry and dip azimuths of the foresets are conspicuously consistent, although the concave‐up and sigmoidal strata commonly alternate downcurrent.The cross‐strata characteristics suggest flood stage deposition from relatively high velocity steady currents heavily laden with suspended sand. Both cross‐set types are interpreted as representing bedforms generated by flow in the dune to upper‐stage plane‐bed transition. The lenticular cross‐sets probably represent periodic dunes, but it is far less clear whether the long bedforms represented by the tabular sets should be classified as dunes, or rather as solit

 

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