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dc.contributor.authorJelby, Mads Engholm
dc.contributor.authorGrundvåg, Sten-Andreas
dc.contributor.authorHelland-Hansen, William
dc.contributor.authorOlaussen, Snorre
dc.contributor.authorStemmerik, Lars
dc.date.accessioned2020-06-09T21:26:01Z
dc.date.available2020-06-09T21:26:01Z
dc.date.issued2019-10-03
dc.description.abstractThe hydrodynamic mechanisms responsible for the genesis and facies variability of shallow‐marine sandstone storm deposits (tempestites) have been intensely debated, with particular focus on hummocky cross‐stratification. Despite being ubiquitously utilized as diagnostic elements of high‐energy storm events, the full formative process spectrum of tempestites and hummocky cross‐stratification is still to be determined. In this study, detailed sedimentological investigations of more than 950 discrete tempestites within the Lower Cretaceous Rurikfjellet Formation on Spitsbergen, Svalbard, shed new light on the formation and environmental significance of hummocky cross‐stratification, and provide a reference for evaluation of tempestite facies models. Three generic types of tempestites are recognized, representing deposition from: (i) relatively steady and (ii) highly unsteady storm‐wave‐generated oscillatory flows or oscillatory‐dominated combined‐flows; and (iii) various storm‐wave‐modified hyperpycnal flows (including waxing–waning flows) generated directly from plunging rivers. A low‐gradient ramp physiography enhanced both distally progressive deceleration of the hyperpycnal flows and the spatial extent and relative magnitude of wave‐added turbulence. Sandstone beds display a wide range of simple and complex configurations of hummocky cross‐stratification. Features include ripple cross‐lamination and ‘compound’ stratification, soft‐sediment deformation structures, local shifts to quasi‐planar lamination, double draping, metre‐scale channelized bed architectures, gravel‐rich intervals, ‘inverse to normal’ grading, and vertical alternation of sedimentary structures. A polygenetic model is presented to account for the various configurations of hummocky cross‐stratification that may commonly be produced during storms by wave oscillations, hyperpycnal flows and downwelling flows. Inherent storm‐wave unsteadiness probably facilitates the generation of a wide range of hummocky cross‐stratification configurations due to: (i) changes in near‐bed oscillatory shear stresses related to passing wave groups or tidal water‐level variations; (ii) multidirectional combined‐flows related to polymodal and time‐varying orientations of wave oscillations; and (iii) syndepositional liquefaction related to cyclic wave stress. Previous proximal–distal tempestite facies models may only be applicable to relatively high‐gradient shelves, and new models are necessary for low‐gradient settings.en_US
dc.descriptionThis is the peer reviewed version of the following article: Jelby, M.E., Grundvåg, S.‐A., Helland‐Hansen, W., Olaussen, S. & Stemmerik, L. (2020). Tempestite facies variability and storm‐depositional processes across a wide ramp: Towards a polygenetic model for hummocky cross‐stratification. <i>Sedimentology, 67</i>, 742-781, which has been published in final form at <a href=https://doi.org/10.1111/sed.12671>https://doi.org/10.1111/sed.12671</a>. This article may be used for non-commercial purposes in accordance with Wiley <a href=https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html>Terms and Conditions for Use of Self-Archived Versions</a>.en_US
dc.identifier.citationJelby, M.E., Grundvåg, S.‐A., Helland‐Hansen, W., Olaussen, S. & Stemmerik, L. (2020). Tempestite facies variability and storm‐depositional processes across a wide ramp: Towards a polygenetic model for hummocky cross‐stratification. <i>Sedimentology, 67</i>, 742-781. https://doi.org/10.1111/sed.12671en_US
dc.identifier.cristinIDFRIDAID 1744428
dc.identifier.doi10.1111/sed.12671
dc.identifier.issn0037-0746
dc.identifier.issn1365-3091
dc.identifier.urihttps://hdl.handle.net/10037/18502
dc.language.isoengen_US
dc.publisherWileyen_US
dc.relation.journalSedimentology
dc.rights.accessRightsopenAccessen_US
dc.rights.holder© 2019 The Authors. Sedimentology © 2019 International Association of Sedimentologistsen_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Sedimentology: 456en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Sedimentologi: 456en_US
dc.titleTempestite facies variability and storm‐depositional processes across a wide ramp: Towards a polygenetic model for hummocky cross‐stratificationen_US
dc.type.versionacceptedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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