Suspended sediment transport and deposition of cyclically interlaminated sediment in a temperate glacial fjord, Alaska, U.S.A.

Cowan, Ellen A.; Powell, Ross D.

doi:10.1144/gsl.sp.1990.053.01.04

Cited by 74 publications

(79 citation statements)

References 24 publications

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“…The considerable thickness of this unit in valleys of the shield necessarily result from an abundant and rapid glaciomarine sedimentation, considering the short period of only 300-400 yr for the ice to retreat and the rapid emergence rate at deglaciation time. Such silty clay deposits are one of the most distinctive constituent of meltwater derived sediments in temperate and subpolar glaciomarine environments (Cowan and Powell, 1990). De2 deposits, exposed in S1a, S20 and S45, are in some cases deformed, showing wavy parallel and chaotic bedding and normal faults.…”

Section: Raised Late Quaternary Depositsmentioning

confidence: 99%

“…They correspond to annual organic varves probably formed during a time-lag between the important spring diatom bloom and clastic summer sedimentation (Elverhøi et al, 1980). Textural and structural characteristics indicate that De2 sediments were transported by turbid meltwater plumes emanating from the glacial margin (hypopycnal flow) and were deposited by suspension-settling (Elverhøi et al, 1980(Elverhøi et al, , 1983Powell, 1981;Görlich, 1986;Cowan and Powell, 1990). The presence of thin sand layers within silty clay beds may be associated with turbulence caused by shifting of the meltwater jet (McCabe et al, 1993) or by submarine gravity flows.…”

Section: Raised Late Quaternary Depositsmentioning

confidence: 99%

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Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

Lajeunesse

Allard

2005

gpq

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This study presents a paleoenvironmental reconstruction of deglaciation dynamics and chronology, glaciomarine and postglacial sedimentation, as well as glacioisostatic recovery in the Rivière Nastapoka area, eastern Hudson Bay. Results indicate that the retreat of Québec-Labrador ice was mainly controlled by topography and was marked by four phases. Radiocarbon dates indicate that deglaciation began about 8.3 ka cal. BP and was characterized by a stillstand of the ice margin in the Nastapoka Hills that lead to the deposition of a drift belt in a high relative sea-level (Phase 1). After this stabilisation, the ice margin retreated rapidly eastward in a region of low relief and deposited a drape of silty clay in a falling relative sea-level (Phase 2). A second phase of stabilization of the ice margin lasted until at least 7.2 ka cal.BP on the higher shield peneplaine east of the limit of the Tyrrell Sea (Phase 3). This lead to the deposition of a belt of glaciofluvial deltas in a lower relative sea-level. Following this stillstand, the eastward retreat and subsequent ablation of the ice in central Québec-Labrador generated meltwater that transported large volumes of glacial sediments by fluvial processes and downcutting of fluvial terraces in previously deposited glaciofluvial and marine sediments (Phase 4). Glacioisostatic rebound reached 0.07 m/yr during the early phase of deglaciation and decreased to 0.04 m/yr between 6 and 5 ka cal. BP and 0.016 m/yr in the last 1000 years.Dans la région de la rivière Nastapoka, le retrait de l’inlandsis du Québec-Labrador sous l’influence de la topographie s’est déroulé en quatre phases. Les datations au radiocarbone montrent que la déglaciation a débuté vers 8,3 ka étal. BP et qu’elle a été caractérisée par une stabilisation du front glaciaire dans les collines Nastapoka ayant mené à la mise en place d’une ceinture de complexes sédimentaires alors que le niveau marin relatif était élevé (phase 1). Par la suite, le front glaciaire a rapidement reculé vers l’est dans une zone au relief peu accidenté en déposant un épais couvert de silt argileux dans les dépressions rocheuses ; le niveau marin relatif était encore élevé (phase 2). Le front glaciaire s’est ensuite de nouveau stabilisé jusqu’à au moins 7.2 ka étal. BP dans une région au relief plus accidenté sur le plateau précambrien, au-delà de la limite orientale de l’invasion de la Mer de Tyrrell (phase 3). Cette pause a mené à la mise en place d’une ceinture de deltas fluvio-glaciaires alors que le niveau marin relatif était plus bas. Puis, avec le retrait complet du front glaciaire de la région et l’ablation de l’inlandsis au centre du Québec-Labrador, les eaux de fonte ont transporté d’importantes quantités de sédiments glaciaires selon des processus fluviaux et l’incision en terrasses des dépôts fluvio-glaciaires et marins déposés antérieurement (phase 4). Le relèvement glacio-isostatique de la région a atteint des taux de 0,07 m/an au début de la déglaciation, puis a diminué pour atteindre 0,04 m/an entre 6 et 5 ka étal....

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Section: Raised Late Quaternary Depositsmentioning

confidence: 99%

Section: Raised Late Quaternary Depositsmentioning

confidence: 99%

Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

Lajeunesse

Allard

2005

gpq

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“…Under sufficiently large discharge, Syvitski (1989) argued that horizontal inertia could push the trajectory of a meltwater plume away from the glacier, and the plume would surface some distance away from the terminus. In the case of lower discharge, the buoyancy force was thought to dominate the inertia, and the meltwater plume is expected to rise along the ice face (Powell 1990;Cowan and Powell 1990).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Meltwater Plumes on the Melting of a Vertical Glacier Face

Kimura

Holland

Jenkins

et al. 2014

Journal of Physical Oceanography

107

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Freshwater produced by the surface melting of ice sheets is commonly discharged into ocean fjords from the bottom of deep fjord-terminating glaciers. The discharge of the freshwater forms upwelling plumes in front of the glacier calving face. This study simulates the meltwater plumes emanated into an unstratified environment using a nonhydrostatic ocean model with an unstructured mesh and subgrid-scale mixing calibrated by comparison to established plume theory. The presence of an ice face reduces the entrainment of seawater into the meltwater plumes, so the plumes remain attached to the ice front, in contrast to previous simple models. Ice melting increases with height above the discharge, also in contrast to some simple models, and the authors speculate that this ''overcutting'' may contribute to the tendency of icebergs to topple inwards toward the ice face upon calving. The overall melt rate is found to increase with discharge flux only up to a critical value, which depends on the channel size. The melt rate is not a simple function of the subglacial discharge flux, as assumed by many previous studies. For a given discharge flux, the geometry of the plume source also significantly affects the melting, with higher melt rates obtained for a thinner, wider source. In a wider channel, two plumes are emanated near the source and these plumes eventually coalesce. Such merged meltwater plumes ascend faster and increase the maximum melt rate near the center of the channel. The melt rate per unit discharge decreases as the subglacial system becomes more channelized.

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“…8B) are interpreted as paired ebb tide slack-water deposits (Visser, 1980;Fenies et al, 1999). Cowan et al (1997Cowan et al ( , 1998 noted annual couplets in glacimarine settings, and Cowan and Powell (1990) described two couplets produced each day by semidiurnal tides where sediment supply from meltwater plumes was tidally controlled, though the AND-2A couplets are thinner and generally finer-grained than both these examples. Bundles of ~2-14 laminae in AND-2A can be interpreted as diurnal, weekly, and perhaps semi-lunar cycles.…”

Section: Interpretation Of Cs2mentioning

confidence: 99%

A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica

et al. 2018

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Suspended sediment transport and deposition of cyclically interlaminated sediment in a temperate glacial fjord, Alaska, U.S.A.

Cited by 74 publications

References 24 publications

Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

The Effect of Meltwater Plumes on the Melting of a Vertical Glacier Face

A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica

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