Recognition and importance of amalgamated sandy meander belts in the continental rock record

Hartley, Adrian J.; Owen, Amanda; Swan, Alistair; Weissmann, Gary S.; Holzweber, Barbara I.; Howell, John; Nichols, Gary; Scuderi, L. A.

doi:10.1130/g36743.1

Cited by 68 publications

(48 citation statements)

References 20 publications

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“…In places, the repeated interbedding of facies F3a and F3b may record multi-storey stacking of bars, consistent with deposition on rapidly migrating bars, possibly in braided rivers M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT (Miall, 1996;Hartley et al, 2016). The intervals of homogenous mudstones with sharp tops and bases which are interbedded with sandstones of this FA are interpreted to have been deposited in low-energy abandoned channels, because facies F3c occurs exclusively in the upper part of this upward fining facies succession (i.e.…”

Section: Discussionmentioning

confidence: 99%

Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway

Cappelle

Ravnås

Hampson

et al. 2017

Marine and Petroleum Geology

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Hightlights:• Core-based sedimentology of Jurassic deltaic strata from offshore Norway• Facies analysis of tide-influenced deltaic and estuarine petroleum reservoirs represented by an overall upward decrease in grain size, decrease in fluvial influence and increase in tidal influence. This evolution is attributed to an allogenic increase in the rate of accommodation space generation relative to sediment supply due to tectonic activity of the rift basin. In addition, during progradation, there was also an autogenic increase in sediment storage on the coastal plain, resulting in a gradual autoretreat of the depositional system. This is manifested in the subsequent aggradation of the system, when coarse-grained sandstones were trapped in proximal locations, while only finer grained sediment reached the coastline, where it was readily reworked by tidal and wave processes.

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Section: Discussionmentioning

confidence: 99%

Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway

Cappelle

Ravnås

Hampson

et al. 2017

Marine and Petroleum Geology

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“…Specific scopes of this research are: (i) to document different modes of bar accretion; (ii) to evaluate the effects of waning‐flood stages on the development and shaping of fluvial bars; and (iii) to outline the internal geometry and depositional relief of pre‐vegetation fluvial bars. The results of this study provide the basis for a critical comparison between Proterozoic and modern fluvial‐bar morphodynamics, and underscore the importance of detailed sedimentological work to support morphodynamic reconstructions based on bar morphology (Hartley et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Precambrian snapshots: Morphodynamics of Torridonian fluvial braid bars revealed by three‐dimensional photogrammetry and outcrop sedimentology

Ghinassi

Ielpi

2017

Sedimentology

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Pre‐vegetation fluvial channels have long been considered predominantly sheet‐like in geometry, owing to hydraulic sections that rapidly widened rather than incise during floods. This motif has been paralleled to that of modern dryland rivers subject to sharp discharge fluctuations during ephemeral floods. However, a number of Precambrian fluvial successions have been recently appraised as the product of deep‐channelled systems characterized by relatively stable – probably perennial – discharge regimes. One such example is the ca 1·0 Ga Applecross Formation, part of the well‐studied Torridon Group of Scotland. To contribute to this debate and to provide refined morphodynamic models for the Applecross Formation, this article presents an integration of three‐dimensional photogrammetry and outcrop sedimentology applied to key exposures at Stoer Peninsula, north‐western Scottish Highlands. Analysis of selected sandbodies reveals that high‐relief fluvial sand bars, both mid‐channel and bank‐attached, evolved within deep, braided‐channel belts. These bars grew through complex mechanisms of accretion and reactivation related to different flood stages: upstream and downstream accretion probably occurred during waning‐flood stages characterized by high hydrograph levels and abundant sediment availability; lateral accretion took place during later waning‐flood stages, and it was associated in some cases with helical recirculation and increase in bend sinuosity. Overall, the depicted morphodynamics are consistent with prolonged flood events that cannot be reconciled with sharply fluctuating discharge regimes. Critical comparisons between the internal geometry of the studied bars and modern counterparts corroborate the findings herein. Thus, this study recommends stricter comparisons between the products of modern braided channels and Precambrian fluvial rock records featuring thick and well‐developed bar forms.

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“…) clearly shows the difference in nature between the Beartooth and the Absaroka systems, as the Beartooth channel bodies are dominated by coarse‐grained more amalgamated channel‐body types indicative of ephemeral alluvial fan deposits (DeCelles et al ., ) (Fig. A), whereas the Absaroka channel‐bodies are more characteristic of more perennial amalgamated meander belt deposits (Hartley et al ., ) (Fig. B and C).…”

Section: Discussionmentioning

confidence: 97%

Basin‐scale predictive models of alluvial architecture: Constraints from the Palaeocene–Eocene, Bighorn Basin, Wyoming, USA

et al. 2018

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Basin‐scale models are required to interpret ancient continental sedimentary successions, and reduce uncertainty in assessing geological resources in basins. Recently, modern studies show distributive fluvial systems to comprise a substantial proportion of modern sedimentary basins, but their role in ancient basin fills has yet to be quantitatively documented at the basin scale. This study analysed key fluvial characteristics to construct a detailed basin‐wide model of the Palaeogene Fort Union and Willwood formations (Bighorn Basin, Wyoming), using observations from modern studies, and ancient system scale studies of distributive fluvial systems, to guide interpretations. Mapping showed these formations to be highly heterogeneous with channel‐body proportion (from 12 to 81%) and geometry types (large amalgamated bodies to isolated channels), grain size (silt to conglomerate), average channel‐body thickness (4 to 20 m) and average storey thickness (3 to 10 m) varying significantly across the basin. Distributive fluvial systems in the form of alluvial and fluvial fans in transverse configurations were recognized as well as a wide axial system, with heterogeneity in the formations being closely aligned to these interpretations. Furthermore, numerous individual depositional systems were identified within the formations (Beartooth Absaroka, Washakie, Owl Creek and axial). Predicted downstream distributive fluvial system trends (i.e. downstream decrease in channel proportion, size and grain size) were identified in the Beartooth, Absaroka and Owl Creek systems. However, predicted trends were not identified in the Washakie system where intrabasinal thrusting disturbed the sequence. Importantly, a wide axial fluvial system was identified, where reverse downstream distributive fluvial system trends were present, interpreted to be the result of the input of transverse systems of variable size. This study provides a new level of detail in the application of basin‐scale models, demonstrating their usefulness in trying to understand and predict alluvial architecture distribution and heterogeneity, with important implications for economic resources and palaeogeographic reconstructions.

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Recognition and importance of amalgamated sandy meander belts in the continental rock record

Cited by 68 publications

References 20 publications

Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway

Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway

Precambrian snapshots: Morphodynamics of Torridonian fluvial braid bars revealed by three‐dimensional photogrammetry and outcrop sedimentology

Basin‐scale predictive models of alluvial architecture: Constraints from the Palaeocene–Eocene, Bighorn Basin, Wyoming, USA

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