Book reviews

Berg, Jan H. van den; Gelder, Andr Van; Mastbergen, Dick R.

doi:10.1046/j.1365-3091.2002.00433.x

Cited by 63 publications

(71 citation statements)

References 33 publications

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“…Angles below the angle of repose are therefore not a useful indicator of the bedform type, however, lee side angle have been found to be steeper than the angle of repose. Such steep lee sides are only possible if the lee side is either eroded in cohesive material or if erosion is being limited by permeability (breaching ; Van den Berg et al, 2002). Erosion at the lee side of the bed form is a strong indicator for cyclic steps or antidunes, because dunes are only eroding on their stoss sides.…”

Section: Discussionmentioning

confidence: 99%

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A comparative study of sediment waves and cyclic steps based on geometries, internal structures and numerical modeling

et al. 2011

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a b s t r a c tAlthough sediment waves cover many levees and canyon floors of submarine fan systems, their relation to the turbidity currents that formed them is still poorly understood. Over the recent years some large erosional sediment waves have been interpreted as cyclic steps. Cyclic steps are a series of slowly upslope migrating bedforms (steps), where each downward step (the lee side of the bedform) is manifested by a steeply dropping flow passing through a hydraulic jump before re-accelerating on the flat stoss side. Here, a general comparison is made between sediment waves and cyclic steps. First, the analogies between their geometries and internal structures are explored. Secondly, a basic numerical model is used to construct stability fields for the formation of cyclic steps. These stability fields are compared with large, existing datasets of both fine-and coarse-grained sediment waves. The numerical results enable an explanation of geometrical trends found over series of sediment waves in the upper part of the Monterey Canyon, on the middle Amazon Fan and on a leveed channel in the Makassar Strait in terms of changes in flow properties of the overriding turbidity current. Based on sedimentological arguments and numerical analysis it is concluded that cyclic steps form a potential alternative for the existing interpretations on the origin of upslope migrating sediment waves.

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Section: Discussionmentioning

confidence: 99%

“…Van den Berg et al (2002) referred to this work to infer the presence of cyclic steps formed by turbidity current initiated by slope instability. The mining created slope instability triggering a mixture of suspended Marine Geology 280 (2011) 40-56 sand and water that developed into a turbidity current forming cyclic steps.…”

Section: Introductionmentioning

confidence: 99%

A comparative study of sediment waves and cyclic steps based on geometries, internal structures and numerical modeling

et al. 2011

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“…5A) show an example of a bedform that was buried rapidly by a faintly-laminated deposit generated by a breach failure composed of fine sand. Rapid burial by such a mass-movement process relies on the presence of an unstable channel bank (Van den Berg et al, 2002) to locally and temporally increase the sediment load settling from suspension, and does not necessarily require the dunes to be inactive at the time of burial. In addition to such rapid burial, alluvial bedforms are also known to be buried slowly under fine-grained sediment with low settling velocities, such as may occur following their abandonment in oxbow-lakes, bar troughs, levees and on floodplains (Figs.…”

Section: Abandoned and Buried Dune Form-setsmentioning

confidence: 99%

Extremes in dune preservation: Controls on the completeness of fluvial deposits

Reesink

Berg

Parsons

et al. 2015

Earth-Science Reviews

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Understanding sedimentary preservation underpins our ability to interpret the ancient sedimentary record and reconstruct paleoenvironments and paleoclimates. Dune sets are ubiquitous in preserved river deposits and are typically interpreted based on a model that describes the recurrence of erosion in a vertical sequence, but without considering spatial variability. However, spatial variability in flow and sediment transport will change the recurrence of erosion, and therefore dune preservation. In order to better understand the limits of these interpretations and outline the causes of potential variability in preservation potential, this paper reviews existing work and presents new observations of an extreme end-member of dune preservation: 'form-sets', formed by dunes in which both stoss-and lee-slopes are preserved intact. These form-sets do not conform to models that are based on the recurrence of erosion, since erosion does not recur in their case, and can therefore be used to evaluate the assumptions that underpin sedimentary preservation. New Ground Penetrating Radar data from the Río Paraná, Argentina, show dune fields that are buried intact within larger scale barforms. These trains of form-sets are up to 300 m in length, are restricted to unit-bar troughs in the upper 5 m of the channel deposits, occur in N 5% of the mid-channel bar deposits, show reactivation surfaces, occur in multiple levels, and match the size of average-flow dunes. A review of published accounts of form-sets highlights a diversity of processes that can be envisaged for their formation: i) abandonment after extreme floods, ii) slow burial of abandoned dune forms by cohesive clay in sheltered bar troughs and meander-neck cut-offs, iii) fast burial by mass-movement processes, and iv) climbing of dune sets due to local dominance of deposition over dune migration. Analysis of these new and published accounts of form-sets and their burial processes highlights that form-sets need not be indicative of extreme floods. Instead, form-sets are closely associated with surrounding geomorphology such as river banks, meander-neck cut-offs, and bars because this larger-scale context controls the local sediment budget and the nature of recurrence of erosion. Locally enhanced preservation by the 'extreme' dominance of deposition is further promoted by finer grain sizes and prolonged changes in flow stage. Such conditions are characteristic, although not exclusive, of large lowland rivers such as the Río Paraná. The spatial control on dune preservation is critical: although at-a-point models adequately describe near-horizontal sets of freely migrating dunes in uniform flows, they are unsuitable for inclined dune co-sets and other cases where multiple scales of bedforms interact. Spatial and temporal variations in flow and sediment transport between the thalweg and different positions on larger bar-forms can change the preservation potential of dunes within river channels. Therefore, dune set thickness distributions are likely grouped in larger-scale un...

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“…hyperpycnal flows; Mulder & Syvitski, 1995); and (3) grain-by-grain retrogressive failure of very steep walls cut into pre-existing sand-rich deposits (Van den Berg, Van Gelder, & Mastbergen, 2002). In case 3 the dilative behavior of a sand-rich deposit precludes development of a disintegrative failure, allowing sediment to directly pass into a turbidity current without temporarily residing in a slide, slump or debris-flow phase (Hampton et al, 1996;Van den Berg et al, 2002).…”

Section: Introductionmentioning

confidence: 99%