Parameterizing parasequences: Importance of shelf gradient, shoreline trajectory, sediment supply, and autoretreat

Ainsworth, R. Bruce; McArthur, Jamie B.; Lang, Simon; Vonk, Adam J.

doi:10.1306/04241918149

Cited by 13 publications

(18 citation statements)

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“…Values of parasequence ‘sand fraction’ (cf. Ainsworth et al ., , ) are computed based on the ratio between the maximum observed thickness of the parasequence shallow‐water sand belt and the maximum observed thickness of the parasequence (Fig. A).…”

Section: Methodsmentioning

confidence: 99%

“…Values of parasequence ‘thickness to sand‐fraction’ ratios (cf. T/SF ratio of Ainsworth et al ., , ) are also computed accordingly, meaning that these metrics differ substantially from the T/SF ratios of Ainsworth et al . (, ), in two ways: (i) the downdip variability in volumetric sand fractions within individual parasequences is not characterized: estimations of sand fractions are less accurate than they would be if it was (as done by Ainsworth et al ., , ); (ii) the maximum, rather than the mean, parasequence thickness is considered.…”

Section: Methodsmentioning

confidence: 99%

“…Further investigation of controls on parasequence architectures is therefore warranted, and quantitative assessments undertaken on large datasets and with consideration of the origin and geological context of parasequences can improve understanding of the significance of controlling factors (cf. Ainsworth et al ., , ; Colombera & Mountney, ).…”

Section: Introductionmentioning

confidence: 99%

“…B). At a fundamental level, the water‐depth and gradient of the shelf or ramp into which a shoreline builds out determine the (decompacted) thickness of a parasequence and influence the rate and amount of shoreline progradation it records (Heward, ; Jervey, ; Emery & Myers, ; Reynolds, ; Ainsworth et al ., , ). The seabed bathymetry is itself a function of the rate at which accommodation is generated and of spatial variations thereof, and is also influenced by the rate of sediment supply and by type and energy of the process regime operating therein (Swift & Thorne, ).…”

Section: Introductionmentioning

confidence: 99%

“…Accordingly, the magnitude of A/S, by regulating the relative amount of nearshore aggradation and shoreline progradation, should be reflected in the regressive shoreline trajectory of a parasequence (Helland‐Hansen & Martinsen, ; Hampson, ; Løseth et al ., ; Helland‐Hansen & Hampson, ). It is also postulated that rates of sediment supply might control the fraction of sand or sandstone of a parasequence, and that, therefore, the ratio between parasequence thickness and sand fraction (T/SF ratio) should represent a proxy of A/S (Ainsworth et al ., , ). Moreover, the A/S ratio determines the preservation potential of normal‐regressive units (Cattaneo & Steel, ; Zecchin et al ., ), and is also thought to control the proportions and vertical trends of lithofacies and facies associations in parasequences, by affecting the relative degree of preservation of different facies belts (Swift et al ., ; Cant, ; Helland‐Hansen & Hampson, ).…”

Section: Introductionmentioning

confidence: 99%

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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: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Colombera

Mountney

2020

Sedimentology

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Sharp‐based shoreface successions reconsidered in three‐dimensions: A forward stratigraphic modelling perspective

Willis

Sun

Ainsworth

2022

The Depositional Record

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Sea-level fall is commonly inferred to generate a sharp-based shoreface succession that displays an abrupt vertical transition from heterolithic, lower shoreface to sandy, upper shoreface deposits across a marine erosion surface. Threedimensional, process physics-based, coupled hydrodynamic-morphodynamic models are constructed to compare bedding architecture and facies patterns of wave-dominated delta deposits preserved during normal (static sea level) and forced (falling sea level) regression and then transgression during subsequent sea-How to cite this article:

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Coal Accumulation Patterns and Paleoclimates in a Carboniferous–Permian Cratonic Basin, North China

Shao,

Fielding,

et al. 2024

Field Trip Guidebook on Chinese Sedimentary Geology

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Parameterizing parasequences: Importance of shelf gradient, shoreline trajectory, sediment supply, and autoretreat

Cited by 13 publications

References 50 publications

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

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

Sharp‐based shoreface successions reconsidered in three‐dimensions: A forward stratigraphic modelling perspective

Coal Accumulation Patterns and Paleoclimates in a Carboniferous–Permian Cratonic Basin, North China

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