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dc.creatorVan Yperen, Anna E.
dc.creatorPoyatos-Moré, Miquel
dc.creatorHolbrook, John M.
dc.creatorMidtkandal, Ivar
dc.date.accessioned2021-01-15T14:41:20Z
dc.date.available2021-01-15T14:41:20Z
dc.date.issued2020-01-06
dc.identifier.urihttps://doi.org/10.1002/dep2.100
dc.identifier.urihttps://repository.tcu.edu/handle/116099117/43065
dc.identifier.urihttps://onlinelibrary.wiley.com/doi/full/10.1002/dep2.100
dc.description.abstractMouth bars are the fundamental architectural elements of proximal deltaic successions. Understanding their internal architecture and complex interaction with coastal processes (fluvial, tide and wave-dominated) is paramount to the interpretation of ancient deltaic successions. This is particularly challenging in low-accommodation systems, because they are commonly characterized by thin, condensed and top-truncated sections. This study analyses the exhumed Cenomanian Mesa Rica Sandstone (Dakota Group, Western Interior Seaway, USA), a fluvio-deltaic system covering a ca 450 km depositional dip-parallel profile. The study targets the proximal deltaic expression of the system, using 22 sedimentary logs (total of 390 m) spatially correlated within a ca 25 km2 study area at the rim of the Tucumcari Basin. Analysis of facies distributions, depositional architecture and spatial extent of stratigraphic surfaces reveals a 6–10 m thick, sharp-based and sand-prone deltaic package, comprising several laterally extensive (>1.4 km width) mouth bars. Composite erosional surfaces infilled with multi-storey fluvial and marine-influenced channel deposits (12–20 m thick, 100–250 m wide) scour locally into the deltaic package. Based on differences in sedimentary structures, bed thicknesses, occurrence of interflood beds and bioturbation indexes, four different sub-environments within single mouth bars were distinguished. These range from mouth-bar axis, off-axis, fringe to distal-fringe deposits, which reflect waning depositional energy with increasing distance from the distributary channel mouth. The interpreted mouth-bar components also show internal variability in dominant process regime, with overall river dominance but local preservation of tide influence in the fringe and distal fringe components. Mouth-bar deposits amalgamate to form an extensive sand-rich sheet body throughout the study area, in which interflood mudstone to very-fine grained sandstone beds are nearly absent. These features reflect successive coalescence of mouth bars in a low accommodation/supply (A/S) setting. These conditions promoted recurrent channel avulsion/bifurcation and thus the potential reworking of previously deposited mouth-bar fringe and distal-fringe sediments, where time and background processes are better recorded. Results of this study evidence internal process-regime variability within mouth-bar components. They also caution against the possible loss of preservation of subordinate coastal processes (e.g. tidal indicators), and consequent underestimation of the true mixed influence in low-accommodation deltaic settings.en_US
dc.language.isoen_USen_US
dc.publisherWiley
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.sourceThe Depositional Record
dc.subjectCoastal processesen_US
dc.subjectDakota groupen_US
dc.subjectdeltaen_US
dc.subjectinterflood bedsen_US
dc.subjectlow accommodationen_US
dc.subjectmouth baren_US
dc.subjectpreservationen_US
dc.titleInternal mouth-bar variability and preservation of subordinate coastal processes in low-accommodation proximal deltaic settings (Cretaceous Dakota Group, New Mexico, USA)en_US
dc.typeArticleen_US
dc.rights.holder2020 van Yperen et al
dc.rights.licenseCC BY 4.0
local.collegeCollege of Science and Engineering
local.departmentGeological Sciences
local.personsHolbrook (GEOL)


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