Triangular-shaped landforms reveal subglacial drainage routes in SW Finland

Mäkinen, Joni; Kajuutti, Kari; Palmu, Jukka‐Pekka; Ojala, Antti E. K.; Ahokangas, Elina

doi:10.1016/j.quascirev.2017.03.024

Cited by 42 publications

(76 citation statements)

References 50 publications

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“…Finally, hummocks may be a combination of erosion and deposition. This is not dissimilar to the interpretation of triangular shaped landforms ('murtoos') which are thought to form from subglacial till transported by 650 creep which is then eroded and shaped by subglacial meltwater, and represents high pressure distributed drainage within a 'weakly connected' zone upstream of channelised drainage (Mäkinen et al, 2017;Ojala et al, 2019).…”

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confidence: 66%

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Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

Lewington

Livingstone

Clark

et al. 2020

Preprint

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Abstract. We identify and map traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada from ArcticDEM data. Meltwater tracks, tunnel valleys and esker splays exhibit several key similarities, including width, spacing, their association with eskers and transitions to and from different types, which together suggest they form part of an integrated drainage signature. We collectively term these features &apos;meltwater corridors&apos; and propose a new model for their formation, based on observations from contemporary ice masses, of pressure fluctuations surrounding a central conduit. We suggest that eskers record the imprint of a central conduit and meltwater corridors the interaction with the surrounding distributed drainage system. The widespread aerial coverage of meltwater corridors (5–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations and variations in spatial distribution and evolution of the subglacial drainage system, which will modulate the ice dynamic response.

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confidence: 66%

“…Meltwater landforms are typically mapped and interpreted individually (e.g. Clark and Walder, 1994;Brennand, 2000;Storrar et al 2013;Burke et al, 2015;Livingstone and Clark, 2016;Mäkinen et al, 2017) rather than as a holistic drainage signature (c.f. 155 Storrar and Livingstone, 2017).…”

mentioning

confidence: 99%

Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

Lewington

Livingstone

Clark

et al. 2020

Preprint

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“…We also identify hummocks with a V‐shaped appearance with apices pointing in the general ice‐flow direction and gentle up‐ice slopes (Peterson et al ., ). Similar V‐shaped hummocks have recently been identified in Finland (Mäkinen et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Hummock corridors in the south‐central sector of the Fennoscandian ice sheet, morphometry and pattern

Peterson

Johnson

2017

Earth Surf Processes Landf

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Subglacial conditions strongly influence the flow of ice‐sheets, in part due to the availability of melt water. Contemporary ice sheets are retreating and are affected by increased melting as climate warms. The south Swedish uplands (SSU) were deglaciated during the relatively warm Bølling‐Allerød interval, and by studying the glacial landforms there it is possible to increase the understanding of the subglacial environment during this period of warming. Across the study area, vast tracts of hummocks have long been recognized. However, recent mapping shows a pattern of elongated zones of hummocks radially oriented, hereafter referred to as ‘hummock corridors’. Morphometric parameters were measured on the hummock corridors using a 2 m horizontal resolution digital elevation model. Corridor width varies between 0.2 and 4.9 km and their length between 1.5 and 11.8 km. A majority of hummock corridors are incised in drumlinised till surfaces. The pattern of hummock corridors shows a clear relation to the overall ice‐flow. Further, hummock corridors do not follow topographic gradients, and in at least one place an esker overlies hummocks on the corridor floor. The lateral spacing of hummock corridors and corridor morphology are similar to tunnel valleys, eskers and glaciofluvial corridors reported elsewhere. Such relationships support a subglacial genesis of the corridors in the SSU by water driven by the subglacial hydraulic gradient and that hummock corridors are forms that can be identified as tunnel valleys and glaciofluvial corridors (GFC). Ages were assigned to hummock‐corridor cross‐sections from a deglacial reconstruction of the Fennoscandian Ice Sheet. By comparing the frequency of corridors per age interval with climate variations from a Greenland ice core, we hypothesize that an increase in the number of corridors is related to the Bølling‐Allerød warming, indicating a higher rate of delivery of surface melt water to the bed at this time. Copyright © 2017 John Wiley & Sons, Ltd.

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“…3; see also Electronic Appendices C:8, C:9, E:32 and E:34). Understanding of these transverse moraine forms is not yet complete and awaits further subsurface data as to their composition; existing data identifies coarse-grained often bouldery cores indicative of limited distances of glacial transport (e.g., Mäkinen et al, 2017). Large areas of hummocky moraine record supraglacial deposition of diamicts as well as sorted glaciofluvial or glaciolacustrine sediment over stagnant ice.…”

Section: Landform and Deposit Classesmentioning

confidence: 99%

“…For example, topographically-irregular bodies of sediment that have been dissected by numerous poorly-integrated channels appear to have accumulated at the lateral margins of under fast flowing ice (Electronic Appendix E:34 and Mäkinen et al, 2017). These may represent poorly integrated subglacial drainage systems.…”

Section: Ice Stream Lobes In Finland and Deglaciation Dynamicsmentioning

confidence: 99%

High-resolution LiDAR mapping of glacial landforms and ice stream lobes in Finland

Putkinen¹,

Eyles²,

Putkinen³

et al. 2017

Bull Geol Soc Finland

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Newly available high resolution airborne LiDAR (Light Detection And Ranging) technology is generating unprecedented next-generation imagery of Earth surface features. LiDAR datasets are being employed by the Geological Survey of Finland (GTK) as part of a new national geological initiative (Glacier Dynamic database: GDdatabase) to rapidly and cost-effectively map glacial landforms and sediments left by the last (Late Weichselian) Fennoscandian Ice Sheet (FIS). There is a high demand for such data in hydrogeological, geoengineering and mineral exploration projects and also for the identification of glacial landforms that provide key information regarding ice sheet rheology, growth and decay. An important step forward with this new technique is the recognition of paleoice stream corridors with fast flowing ice (> 3 km yr -1 based on modern ice sheets), surrounded by stagnant or sluggish-flowing ice. Precise geomorphic criteria are now available for recognition of paleo-ice streams, based on the elongation of subglacial streamlined bedforms and the presence of megascale glacial lineations. Flow sets of drumlins and megascale glacial lineations can now be mapped in high resolution using LiDAR and are now seen as genetically related forms in a continuum that records increasing ice flow velocity and the creation of a low friction bed. This paper briefly outlines the nature of the GDdatabase and the methodology behind its construction and provides examples of principal bedform types that record the dynamic interplay of paleo-ice stream lobes in the Finnish sector of the last FIS.

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Triangular-shaped landforms reveal subglacial drainage routes in SW Finland

Cited by 42 publications

References 50 publications

Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

Hummock corridors in the south‐central sector of the Fennoscandian ice sheet, morphometry and pattern

High-resolution LiDAR mapping of glacial landforms and ice stream lobes in Finland

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