Sedimentary architecture of a glaciolacustrine braidplain delta: proxy evidence of a pre‐Middle Wisconsinan glaciation (Grimshaw gravels, Interior Plains, Canada)

Slomka, Jessica M.; Hartman, G.M.D.

doi:10.1111/bor.12355

Cited by 3 publications

(2 citation statements)

References 94 publications

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“…4). They fall loosely downwards, producing characteristic layers with the coarsest grains and the greatest thickness in the lower parts of the foresets -the so-called toesets (Nemec, 1990;White, 1992;Slomka & Hartman, 2019). Under conditions of higher concentration of grains, transport takes place as a debris flow.…”

Section: Deltasmentioning

confidence: 99%

Lacustrine deltas and subaqueous fans: almost the same, but different – a review

Gruszka

Zieliński

2021

Geologos

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Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the hydraulic conditions for their formation, development and sedimentary records are different. The present review discusses the results of previously published studies of fan deltas (Gilbert-type deltas) and subaqueous fans of lacustrine and glaciolacustrine environments. The depositional mechanisms of deltas and subaqueous fans, textural and structural features of the lithofacies associations and their typical lithofacies are presented. The characteristics of subaqueous fans, which are still relatively poorly understood and are often overlooked in sedimentological interpretations of lacustrine sedimentary successions, receive particular attention. The palaeoenvironmental and lithological differences between deltas and sub-aqueous fans are highlighted.

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Section: Deltasmentioning

confidence: 99%

Lacustrine deltas and subaqueous fans: almost the same, but different – a review

Gruszka

Zieliński

2021

Geologos

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“…Steep glacifluvial systems commonly form small‐scale fan shaped sediment bodies, referred to as sandar (singular: sandur ), which may resemble alluvial fans. Gently sloping glacifluvial systems form larger‐scale braidplains, which may merge into ice‐marginal trunk rivers (Zielinski & van Loon, 2002, 2003; Blažauskas et al ., 2007) or feed into glacifluvial deltas (Slomka & Hartman, 2019).…”

Section: Upper‐flow‐regime Bedforms In Different Glacigenic Depositional Environmentsmentioning

confidence: 99%

Bedforms and sedimentary structures related to supercritical flows in glacigenic settings

et al. 2020

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Upper-flow-regime bedforms, including upper-stage-plane beds, antidunes, chutes-and-pools and cyclic steps, are ubiquitous in glacigenic depositional environments characterized by abundant meltwater discharge and sediment supply. In this study, the depositional record of Froude near-critical and supercritical flows in glacigenic settings is reviewed, and similarities and differences between different depositional environments are discussed. Upper-flow-regime bedforms may occur in subglacial, subaerial and subaqueous environments, recording deposition by free-surface flows and submerged density flows. Although individual bedform types are generally not indicative of any specific depositional environment, some observed trends are similar to those documented in non-glacigenic settings. Important parameters for bedform evolution that differ between depositional environments include flow confinement, bed slope, aggradation rate and grain size. Cyclic-step deposits are more common in confined settings, like channels or incised valleys, or steep slopes of coarse-grained deltas. Antidune deposits prevail in unconfined settings and on more gentle slopes, like glacifluvial fans, sandrich delta slopes or subaqueous (ice-contact) fans. At low aggradation rates, only the basal portions of bedforms are preserved, such as scour fills related to the hydraulic-jump zone of cyclic steps or antidune-wave breaking, which are common in glacifluvial systems and during glacial lake-outburst floods and (related) lake-level falls. Higher aggradation rates result in increased preservation potential, possibly leading to the preservation of complete bedforms. Such conditions are met in sediment-laden j€ okulhlaups and subaqueous proglacial environments characterized by expanding density flows. Coarser-grained sediment leads to steeper bedform profiles and highly scoured facies architectures, while finer-grained deposits display less steep bedform architectures. Such differences are in part related to stronger flows, faster settling of coarse clasts, and more rapid breaking of antidune waves or hydraulic-jump formation over hydraulically rough beds.

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The Empress Group in Alberta, Canada

Hartman,

Pawley,

Utting

et al. 2024

Can. J. Earth Sci.

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Basal gravel and sand mantling the bedrock floors of buried valleys throughout the Canadian Interior Plains, and conformably overlying proglacial lacustrine sediment, comprise the Empress Group. While previously conceptualized as stratigraphically equivalent deposits of preglacial rivers prior to the first and most extensive continental and montane glaciations, subsequent stratigraphic studies indicated that buried valley basal gravel must have been deposited between, or during, progressively more extensive continental glaciations and could not be stratigraphically equivalent throughout the buried valley network. However, in the general absence of formation-rank stratigraphic description of basal gravel units that might better inform the geologic history of the deposits, most workers simply consider Empress Group sediments time-transgressive. In this paper, we examine basal gravel at provincial and regional scales to understand its genesis and geologic history. At the provincial scale, we map basal gravel in three dimensions using a novel machine learning approach. At the regional scale, we formally define basal gravel formations at either end of the largest buried valley system in Alberta, which informs its glacial history and physiographic development and shows the importance of formation-rank stratigraphic description. Our results indicate that the buried valley network across Alberta is palimpsest in genesis and basal gravel units within it are chronostratigraphically intercalated between tills. We advocate that the Empress Group definition be extended across Alberta with modifications to improve its clarity and utility, and formally define the Old Fort, Unchaga, Ipiatik, and Winefred formations as part of the Empress Group.

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Sedimentary architecture of a glaciolacustrine braidplain delta: proxy evidence of a pre‐Middle Wisconsinan glaciation (Grimshaw gravels, Interior Plains, Canada)

Cited by 3 publications

References 94 publications

Lacustrine deltas and subaqueous fans: almost the same, but different – a review

Lacustrine deltas and subaqueous fans: almost the same, but different – a review

Bedforms and sedimentary structures related to supercritical flows in glacigenic settings

The Empress Group in Alberta, Canada

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