Asymmetry in Holocene river deltas: Patterns, controls, and stratigraphic effects

Korus, Jesse T.; Fielding, Christopher R.

doi:10.1016/j.earscirev.2015.07.013

Cited by 52 publications

(23 citation statements)

References 137 publications

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“…Protrusion reworking can also include the formation of flanking spits on both active deltas (Anthony, 2015) and abandoned lobes (Nienhuis et al, 2013). Protrusion flattening and the attendant shoreline straightening may involve increasing asymmetry of the delta as part of the trajectory of delta destruction (Figure 3), although asymmetry may be an intrinsic attribute of many prograding deltas, expressed by a more or less skewed delta planshape that expresses an uneven distribution of sediment on either side of the central axis of the delta (Bhattacharya and Giosan, 2003;Li et al, 2011;Korus and Fielding, 2015). Anthony (2015) showed that many Mediterranean deltas presently exhibit a symmetrical or near-symmetrical plan shape that represents mutual adaptation between river flux, delta morphology, and wave approach.…”

Section: Research Articlementioning

confidence: 99%

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

Besset

Anthony

Sabatier

2017

Elementa: Science of the Anthropocene

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The Mediterranean basin (including the Black Sea) is characterized by a plethora of deltas that have developed in a wave-influenced setting. Many of these deltas are sourced in sediments by river catchments that have been variably dammed. The vulnerability status of a selection of ten deltas subject to different levels of reduction in fluvial sediment supply following damming was analysed by quantifying changes in delta protrusion area and protrusion angle over the last 30 years. The rationale for choosing these two metrics, which do not require tricky calculations of longshore bedload transport volumes and river ‘influence’, is that as sediment supply wanes, increasing relative efficiency of waves leads to longshore redistribution of reworked sediments and progressive ‘flattening’ of the delta protrusion. The results show that eight of the ten deltas (Nile, Rhône, Ebro, Ceyhan, Arno, Ombrone, Moulouya, Medjerda) are in erosion, whereas two (Danube, Po) show stability, but the statistical relationship between change in delta protrusion area and sediment flux reduction is poor, thus suggesting that the role of dams in causing delta shoreline erosion may have been over-estimated. But this poor relationship could also be due to a long temporal lag between dam construction and bedload removal and transport to the coast downstream of dams, and, where the delta protrusion is being eroded, to bedload trapping by shoreline engineering structures and by elongating delta-flank spits. Other potential influential factors in shoreline change include subsidence, sea-level rise, storminess, exceptional river floods, and managed sediment releases downstream of dams. A longer observation period and high-resolution sediment-budget studies will be necessary to determine more definitively to which extent continued trapping of sediment behind dams will impact overall delta stability in the Mediterranean and Black Seas. Mitigation of delta erosion is likely to become costlier under continued sediment starvation and sea-level rise.

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Section: Research Articlementioning

confidence: 99%

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

Besset

Anthony

Sabatier

2017

Elementa: Science of the Anthropocene

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“…Also, there is no process‐oriented justification for considering the sand fraction indicative of the rate of sediment supply (Ainsworth, ; Ainsworth et al ., , ), since the sand‐belt thickness depends on the calibre of sediment being supplied, on its fractionation through subenvironments (cf. Anthony, ; Korus & Fielding, ; van der Vegt et al ., ), and on the sand–mud transition depth (Dunbar & Barrett, ; George & Hill, ), that is, it depends on the process regime that operates in marine environments. From this perspective, it is also necessary to consider how parasequence thickness and sand fraction could covary because of relationships that exist between shelf depth and sand‐dispersal mechanisms, for example in relation to the fact that typically the coasts of shallower shelves are exposed to less energetic waves but experience larger storm surges (Resio & Westerink, ; Immenhauser, ).…”

Section: Discussionmentioning

confidence: 99%

Accommodation and sediment‐supply controls on clastic parasequences: A meta‐analysis

Colombera

Mountney

2020

Sedimentology

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This study combines data from many published case studies to undertake a quantitative characterization of clastic parasequences, with the aim to determine how accommodation, sediment supply and autogenic sediment-storage dynamics are recorded in their sedimentary architecture and stacking patterns. Results of this study are used to critically evaluate the validity of paradigms and models that are routinely used to explain and predict trends in the anatomy and arrangement of parasequences. Data on 957 parasequences from 62 case studies of clastic, shallow-water successions were coded in a relational database, which includes outcrop and subsurface datasets of ancient and Quaternary examples. These units cover the preserved records of both river-dominated deltas and wave-dominated coasts, representing shoreline transits over a breadth of timescales, likely of both local and regional extent. The role of extant accommodation, rates of creation of accommodation and rates of sediment supply in determining parasequence architecture is assessed through analysis of relationships between: (i) proxies of these variables at different scales (rates of aggradation and progradation, facies-belt shoreline trajectories, systems-tract type, parasequence-set stacking patterns, parasequence progradation angle and stratigraphic rise, size of feeder rivers); and (ii) parameters that describe the geometry and stacking style of parasequences, and associated shallow-water sand bodies. Statistical analyses of database outputs indicate which proxies of accommodation, sediment supply and accommodation/sediment-supply ratio are significant as predictors of parasequence architecture, and allow for interpretations of the importance of allogenic and autogenic factors. The principal results of this study reveal the following: (i) parasequence thickness varies as a function of water depth, accommodation generation and erosional truncation, and these variations are also reflected across types of systems tracts and parasequence sets; (ii) the dip length of parasequence sand bodies demonstrates scaling with measures of accommodation/sedimentsupply ratio at multiple scales, partly in relation to the possible effect of sediment supply on progradation rates; (iii) in systems tracts, stratigraphic trends in parasequence stacking due to autogenic mechanisms or to acceleration or deceleration in relative sea-level fluctuations are not revealed quantitatively; (iv) some association is seen between the abundance of deltaic or river-dominated parasequences and progradational stacking; (v) positive but modest correlation is observed between measures of river-system size and the dip length of shallow-marine parasequence sand bodies. The resulting insights can be applied to guide sequence stratigraphic interpretations of the rock record and the characterization of sub-seismic stratigraphic architectures of subsurface successions. 1667

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Section: Clinoforms and Clinothems: An Introductionmentioning

confidence: 99%

“…Seaward of major deltas worldwide, modern continental margins exhibit extensive intra‐shelf muddy clinothems, up to several tens of metres thick (Korus & Fielding, 2015). These clinothems typically have sediment accumulation rates exceeding 1.5 cm/yr and have been building since the mid Holocene, when sea level approached its present position (Korus & Fielding, 2015; Stanley & Warne, 1994). Furthermore, such modern deltaic systems are characterized by compound clinoforms (Swenson, Paola, Pratson, Voller, & Murray, 2005) where progradation mainly takes place in two distinct areas forming subaerial and subaqueous deltas (Figure 1).…”

Section: Clinoforms and Clinothems: An Introductionmentioning

confidence: 99%

Clinoforms and clinothems: Fundamental elements of basin infill

et al. 2020

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This special issue dealing with the recent advances on modern and ancient clinoform‐stratified sedimentary successions arises from a European Geoscience Union (EGU) session “Clinoform drivers and stratigraphic products in siliciclastic and carbonate successions”, Vienna, April 2018. Clinoforms and clinothems represent a dominant architectural style of strata in many sedimentary environments, including deltaic and nondeltaic shorelines in both marine and lacustrine settings, and are one of the key building blocks of the sedimentary record. This Special Issue in Basin Research aspires to represent a step forward in understanding formation and preservation of these fundamental stratigraphic elements. As this Special Issue documents, a comprehensive understanding of clinoformal strata requires a multidisciplinary and multi‐scale approach. Sixteen papers present case studies from a variety of tectonic settings worldwide, investigated with an array of methods, including seismo‐stratigraphy, well logs, cores, high‐resolution biostratigraphy, outcrop studies and modern bathymetric data. While observations document sedimentary processes and products in sedimentary basins, numerical models are necessary to provide a quantitative basis for the extrapolation of these processes and strata at different temporal and spatial scales. The papers highlight at least five main research avenues that we briefly introduce and discuss below: (a) clinoforms and clinothems as sedimentary archives; (b) the nested nature of clinoformal strata and implications for the trajectory of the rollover point(s); (c) quantitative clinoform parameters and dynamic indices; (d) architecture, growth and sequence stratigraphy of marine versus lacustrine clinoformal strata; and (e) clinoforms and geological time. This introduction also contains brief descriptions of each paper of the Special Issue.

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Asymmetry in Holocene river deltas: Patterns, controls, and stratigraphic effects

Cited by 52 publications

References 137 publications

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

Accommodation and sediment‐supply controls on clastic parasequences: A meta‐analysis

Clinoforms and clinothems: Fundamental elements of basin infill

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