On the geological significance of clastic parasequences

Colombera, Luca; Mountney, Nigel P.

doi:10.1016/j.earscirev.2019.103062

Cited by 21 publications

(22 citation statements)

References 134 publications

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“…The SMAKS includes data on sequence stratigraphic units and surfaces, among other entities (Colombera et al ., ). As of November 2019, SMAKS contained data on tens of thousands of sedimentary units, including over 2000 sequence‐stratigraphic units, of which 1163 were parasequences that had originally been detailed in 64 case studies (Colombera & Mountney, ). Data on 957 parasequences from 62 case studies (Table ) are used in this work.…”

Section: Methodsmentioning

confidence: 99%

“…In SMAKS, parasequences are characterized employing several attributes, including genetic classifications of their deposits (Colombera & Mountney, ); interpretations by the original authors are relied upon. The interpreted depositional environment of parasequences is classified as ‘deltaic’, ‘shoreface’ sensu lato (i.e.…”

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%

“…Uncertainty on whether a sedimentary unit represents a true parasequence is also caused by criteria for identifying forced regression, such as downstepping stratal geometries, since these may be difficult to recognize in outcrop and across wells, and below the resolution of seismic datasets. Other issues with the definition and diagnostic criteria of parasequences, discussed in detail elsewhere (Swift et al ., ; Posamentier & James, ; Arnott, ; Christie‐Blick & Driscoll, ; Kamola & Van Wagoner, ; Zecchin, , ; Embry & Johannessen, ; Catuneanu, ,b; Colombera & Mountney, ), make the recognition of parasequences partly subjective: resulting inconsistencies in their application must be acknowledged when adopting these units as the basis for interpreting controls on the stratigraphic record. An issue that is of particular significance to the analyses presented below is the fact that parasequences can be defined for stratal patterns that develop at different scales, in sedimentary units that can be nested hierarchically, even in the same succession (cf.…”

Section: Introductionmentioning

confidence: 99%

“…Herein, the focus is particularly on the role of accommodation and sediment supply as controls on parasequence architectures. A synthesis of many examples of parasequences aiming to offer some insight into their geological significance is presented in a companion paper (Colombera & Mountney, ).…”

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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Deltas: New paradigms

Zavala,

Arcuri,

Zorzano

et al. 2024

The Depositional Record

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Deltas are deposits directly accumulated by land‐generated gravity flows in a standing body of water. The paradigm of deltaic sedimentation has dramatically changed during recent years, from the popular very simplified ternary models of marine littoral deltas towards more realistic and comprehensive models, considering the importance of sediment‐laden river discharges. Ternary delta models were designed for clean rivers, where a stream flow drags the sediments. Depending on the basin dynamics, these littoral deposits can be modified, forming tidal‐dominated, wave‐dominated or fluvial‐dominated littoral deltas. In recent years, a new classification of delta systems was proposed, based on contrasting the salinity of the receiving water body with the bulk density of the incoming fluvial discharge. Rivers are highly dynamic systems, and their discharges can be very variable in terms of flow duration and sediment concentration. Additionally, the salinity of the receiving water body can exhibit significant variability, especially in closed lakes and epicontinental seas, ranging from freshwater to brines. This scenario allows the distinction of three major delta categories (hypopycnal, homopycnal and hyperpycnal deltas) which can be in turn subdivided, defining seven delta types. Hypopycnal deltas form when the bulk density of the incoming flow is lower than the density of the water in the basin, allowing the definition of three delta types, corresponding to hypersaline littoral deltas, marine littoral deltas and brackish littoral deltas. Homopycnal deltas form when the bulk density of the incoming flow is similar to the density of the water in the basin, defining a delta type termed homopycnal littoral deltas. Hyperpycnal deltas form when the bulk density of the incoming flow is higher than the density of the water in the basin, allowing the definition of three categories termed hyperpycnal littoral deltas, hyperpycnal subaqueous deltas and hyperpycnal fan deltas.

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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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On the geological significance of clastic parasequences

Cited by 21 publications

References 134 publications

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

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

Deltas: New paradigms

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

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