Morphology and sedimentology of a giant supraglacial, ice-walled, jökulhlaup channel, Skeiðarárjökull, Iceland: implications for esker genesis

Russell, A. J.; Knudsen, Óskar; Fay, H.; Marren, Philip M.; Heinz, J.; Tronicke, Jens

doi:10.1016/s0921-8181(00)00073-4

Cited by 60 publications

(40 citation statements)

References 30 publications

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“…These large-scale polymodal cross-strata are similar in scale and texture to those found in high-energy fluvial settings (O'Connor, 1993;Carling, 1996) and on delta/subaqueous outwash fans (Martini, 1990;Nemec, 1990;Nemec et al, 1999). Largescale, polymodal, graded, cross-strata could represent the simultaneous deposition of traction and suspended load Knudsen, 1999a,b, 2002;Russell et al, 2001;Benvenuti and Martini, 2002;Carling et al, 2002), but may also suggest debris-flow activity generated on delta foresets (Allen, 1984;Nemec, 1990;Nemec et al, 1999). Massive cross-strata grade vertically into silty sands, which represent lower energy deposition and a reduction in sedimentation rate ( Fig.…”

Section: Sections 1-3: Interpretationmentioning

confidence: 69%

“…Sedimentary evidence within sections 1-3 suggests repeated, very high-energy subaerial depositional events (jökulhlaups) flowing directly into the Lundy from the north. These deposits are wholly incompatible with deposition from low-magnitude meltwater flows and fulfill all criteria for jökulhlaup deposition (Maizels and Russell, 1992;Maizels, 1993Maizels, , 1997Russell, 1994;Knudsen, 1999a,b, 2002;Russell and Marren, 1999;Russell et al, 2001;Marren, 2002). The present topography of the Lundy-Cour area requires meltwater associated with jökulhlaup deposition in the upper pit to drain in a westerly direction through the Lundy Channel (Fig.…”

Section: Discussionmentioning

confidence: 88%

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High‐energy sedimentation, Creag Aoil, Spean Bridge, Scotland: implications for meltwater movement and storage during Loch Lomond Stadial (Younger Dryas) ice retreat

Russell¹,

Tweed²,

Harris³

2003

J Quaternary Science

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This paper examines the origin and significance of Loch Lomond Stadial (Younger Dryas) gravel deposits at Creag Aoil, Spean Bridge, Scotland. Sedimentation into ice-dammed lakes in Glen Roy and Glen Spean associated with shorelines at 260 m, 325 m and 350 m is well-documented, yet little is known about later, lower level lakes near Spean Bridge. Excavations on the northern flanks of the Lundy Channel revealed exposures into a 35-40 m thickness of sand and gravel. These sediments reflect deposition in a subaqueous environment experiencing repeated short-lived periods of high-energy subaerial deposition. Deformation structures within subaqueous deposits are associated with at least two ice-push events. This study presents new evidence for the existence of ice-dammed lakes at elevations between 260 m and 113 m and for periodic jökulhlaups draining southwest via the Lundy Channel. Active glacier ice associated with the deposits flowed northwest to southeast, driving meltwater across the Great Glen to the Lundy Channel. Glacier retreat was punctuated by periodic minor readvances. Progressive ice retreat was accompanied by ice thinning, and changes in ice-flow direction and subglacial meltwater routing. These findings add to knowledge of Loch Lomond Stadial deglaciation around Spean Bridge and have implications for our understanding of lacustrine glacier margins during deglaciation.

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Section: Sections 1-3: Interpretationmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 88%

High‐energy sedimentation, Creag Aoil, Spean Bridge, Scotland: implications for meltwater movement and storage during Loch Lomond Stadial (Younger Dryas) ice retreat

Russell¹,

Tweed²,

Harris³

2003

J Quaternary Science

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“…Existing models of jökulhlaup sedimentation are only applicable to proglacial settings (e.g. Maizels, 1993aMaizels, ,b, 1997, whereas recent research recognizes that a range of sub-, en-and supraglacial depositional environments can potentially exist during jökulhlaups (Russell, 1994;Tweed and Russell, 1999;van der Meer et al, 1999;Roberts et al, 2000a, b;Russell et al, 2001). These recent findings call for a greater recognition and understanding of glaciofluvial processes operating within glaciers during jökulhlaups.…”

Section: J Roberts Et Almentioning

confidence: 99%

“…The rhythmic nature of sand and gravel couplets signifies major flow pulsations, as observed elsewhere within high-energy slackwater locations during the November 1996 jökulhlaup (cf. Russell and Knudsen, 1999b;Russell et al, 2001). The fact that crude bedding within the pipe itself could be traced upwards into a mushroom-shaped unit consisting of a transition from vertical to horizontal beds, demonstrates that deposition within the pipe occurred simultaneously with overlying sediments.…”

Section: Sectionmentioning

confidence: 99%

Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland

Roberts

Russell

Tweed

et al. 2001

Earth Surf Processes Landf

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This paper presents sedimentary evidence for rapid englacial debris entrainment during jökulhlaups. Previous studies of jökulhlaup sedimentology have focused predominantly on proglacial impact, rather than depositional processes within glaciers. However, observations of supraglacial floodwater outbursts suggest that englacial sediment emplacement is possible during jökulhlaups. The November 1996 jökulhlaup from Skeidarárjökull, Iceland presented one of the first opportunities to examine englacial flood deposits in relation to former supraglacial outlets. Using observations from Skeidarárjökull, this paper identifies and explains controls on the deposition of englacial flood sediments and presents a qualitative model for englacial jökulhlaup deposition. Englacial jökulhlaup deposits were contained within complex networks of upglacier-dipping fractures. Simultaneous englacial deposition of fines and boulder-sized sediment demonstrates that englacial fracture discharge had a high transport capacity. Fracture geometry was an important control on the architecture of englacial jökulhlaup deposits. The occurrence of pervasively frozen flood deposits within Skeidarárjökull is attributed to freeze-on by glaciohydraulic supercooling. Floodwater, flowing subglacially or through upglacier-dipping fractures, would have supercooled as it was raised to the surface faster than its pressure-melting point could increase as glaciostatic pressure decreased. Evidence for floodwater contact with the glacier bed is supported by the ubiquitous occurrence of sheared diamict rip-ups and intra-clasts of basal ice within jökulhlaup fractures, deposited englacially some 200-350 m above the bed of Skeidarárjökull. Evidence for fluidal supercooled sediment accretion is apparent within stratified sands, deposited englacially at exceptionally high angles of rest in the absence of post-depositional disturbance. Such primary sediment structures cannot be explained unless sediment is progressively accreted to opposing fracture walls. Ice retreat from areas of former supraglacial outbursts revealed distinct ridges characterized by localized upwellings of sediment-rich floodwater. These deposits are an important addition to current models of englacial sedimentation and demonstrate the potential for post-jökulhlaup landform development.

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“…Deposition of an esker happens within or in front of the tunnel mouth (Banerjee and McDonald 1975;Mäkinen 2003;Boulton et al 2009), within the subglacial (Syverson et al 1994;Warren and Ashley 1994;Brennand 2000;Campbell 2003;Boulton et al 2009) or englacial (Syverson et al 1994;Campbell 2003;Burke et al 2009) tunnels, or even in the supraglacial environment (Russell et al 2001). Eskers have long been known as a natural source of groundwater (De Geer 1968;Parsons 1970;Artimo et al 2003;Bolduc et al 2006;Okkonen et al 2010), and they are effective sites for MAR (e.g.…”

Section: Introductionmentioning

confidence: 99%

Time-lapse electrical resistivity tomography of a water infiltration test on Johannishus Esker, Sweden

2014

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Managed aquifer recharge (MAR) is an efficient way to remove organic matter from raw water and, at the same time, reduce temperature variation. Two MAR sites were constructed by Karlskrona municipality on Johannishus Esker in Sweden. One of these sites, Vång, was monitored for electrical conductivity and electrical resistivity (using electrical resistivity tomography -ERT) during a 9-week tracer infiltration test. The aim of the monitoring was to map the pathways of the infiltrated water, with the overall goal to increase the efficiency of the MAR. ERT proved useful in determining both the nature of the esker formation and the water migration pathways. In Vång, the esker ridge follows a tectonically controlled paleovalley. The fault/fracture zone in the bedrock along this paleo-valley was mapped. During the tracer test, the infiltrated water was detected in the area close to the infiltration ponds, whereas far-situated observation wells were less affected. For sequential infiltration and recharge periods in MAR, the timing of the well pumping is another important factor. Natural groundwater flow direction was a determinant in the infiltration process, as expected. ERT measurements provide supplementary data for site selection, for monitoring the functionality of the MAR sites, and for revealing the geological, hydrogeological and structural characteristics of the site.

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Morphology and sedimentology of a giant supraglacial, ice-walled, jökulhlaup channel, Skeiðarárjökull, Iceland: implications for esker genesis

Cited by 60 publications

References 30 publications

High‐energy sedimentation, Creag Aoil, Spean Bridge, Scotland: implications for meltwater movement and storage during Loch Lomond Stadial (Younger Dryas) ice retreat

High‐energy sedimentation, Creag Aoil, Spean Bridge, Scotland: implications for meltwater movement and storage during Loch Lomond Stadial (Younger Dryas) ice retreat

Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland

Time-lapse electrical resistivity tomography of a water infiltration test on Johannishus Esker, Sweden

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