FLUVIATILE SEDIMENTARY STRUCTURES IN THE WOOD BAY SERIES (DEVONIAN) OF SPITSBERGEN

Abstract

SUMMARYA noteworthy feature of parts of the Series is the development of cyclothems which consist of: scoured surface, coarse member, fine member, scoured surface. General environments, suggested by this and fossil evidence, are: erosion in river bed, deposition in river bed, deposition in overbank area, erosion in river bed. Structures within the sets of strata include: no lamination, flat bedding, small and large‐scale cross‐lamination, parting lineation. The significance of each is discussed. Sole structures, occurring on the scoured surfaces, are described. They include: groove casts, crescents, flute casts, a variety of long welts, and unoriented structures. These are mainly scour structures but some may be subaerial marks, and there is also evidence for post‐depositional flowage. The value of these structures as indicators of palaeocurrent and ultimately palaeoslope directions is discussed with examples. Measurements of sole structures, parting lineations and ripples have been more profitable than large‐scale cross‐stratification or contorted lamination.