Morphology, internal structure and mechanics of small longitudinal (seif) dunes in an aeolian horizon of the Proterozoic Dhandraul Quartzite, India
Article first published online: 14 JUN 2006
Volume 40, Issue 1, pages 79–85, February 1993
How to Cite
CHAKRABORTY, C. (1993), Morphology, internal structure and mechanics of small longitudinal (seif) dunes in an aeolian horizon of the Proterozoic Dhandraul Quartzite, India. Sedimentology, 40: 79–85. doi: 10.1111/j.1365-3091.1993.tb01092.x
- Issue published online: 14 JUN 2006
- Article first published online: 14 JUN 2006
- (Manuscript received 3 June 1992; revision received 25 September 1992)
The excellently preserved metre-scale, linear bedforms in an aeolian horizon of the Proterozoic Dhandraul Quartzite, India, show oppositely dipping strata arranged in a zigzag pattern. The strata are dominantly of translatent type, deposited by along-crest migrating ripples preserved on the flanks of dunes. The bedforms thus may be interpreted in a morphodynamic sense as longitudinal (seif) dunes.
In order to determine the regional palaeoflow pattern, the migration directions of ripples preserved at the top of sheet sandstones that are associated with the dune cross-strata and internally show subhorizontal translatent strata were measured. A directionally varying flow with a mean direction nearly parallel to the mean axial trend of the dunes is indicated. The kinematics of the dunes were thus largely the result of alternate operation of two oblique flow components, each of which was deflected at a dune crest into an along-crest flow on the downwind flank of the dune. The deflected flow formed along-crest migrating ripples, which in turn deposited climbing ripple strata. Alternate deposition on the two opposite flanks resulted in near vertical accretion of the dunes, as is indicated by the zigzag pattern of stratal arrangement.