Glacial geological studies of surge-type glaciers in Iceland — Research status and future challenges

Inǵólfsson, Ólafur; Benediktsson, Ívar Örn; Schomacker, Anders; Kjær, Kurt H.; Brynjólfsson, Skafti; Jónsson, Sverrir Aðalsteinn; Korsgaard, Niels J.; Johnson, Mark D.

doi:10.1016/j.earscirev.2015.11.008

Cited by 67 publications

(45 citation statements)

References 193 publications

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“…; Ingólfsson et al . ). In spite of improved knowledge of the Late Weichselian deglaciation history of Iceland in recent decades the records are still sporadic and often poorly constrained in time (Geirsdóttir et al .…”

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confidence: 97%

Refining the history of Younger Dryas and Early Holocene glacier oscillations in the Borgarfjörður region, western Iceland

Sigfúsdóttir

Benediktsson

2019

Boreas

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The lower Borgarfjörður region, western Iceland, has been central to the reconstructions of the dynamics and collapse of the Icelandic Ice Sheet during the deglaciation. Here, extensive stratigraphical sections and landforms provide a rare opportunity to study past glacier dynamics in this part of Iceland. Previous studies reveal that a large outlet glacier in Borgarfjörður advanced during the Late Weichselian resulting in large‐scale deformation of glaciomarine sediments and the formation of a series of ice‐marginal moraines. However, the events recorded by these sediments and landforms are poorly constrained in time. We present and discuss 22 new radiocarbon dates in the context of recent reconstructions of the regional glacier dynamics in order to constrain the timing of the glacier oscillations. The results show that a dynamic, marine‐terminating glacier advanced out of Borgarfjörður sometime after c. 13.0 cal. ka BP, resulting in the formation of an extensive moraine complex. The timing indicates that the advance occurred during climate cooling and widespread glacier expansions within the Younger Dryas. Followed by the first initial advance, the glacier exhibited at least five re‐advances punctuated by phases of retreat. Each re‐advance terminated proximal (within 5 km) to the outermost moraine complex although the extent of periodic retreat and the exact timing of these oscillations are unknown. All these phases of re‐advance occurred prior to the onset of the Holocene (around 11.7 cal. ka BP), during which marine fauna re‐colonized the area and the Borgarfjörður glacier retreated from the moraines. During the Early Holocene (sometime after c. 11.3 cal. ka BP), the Borgarfjörður glacier re‐advanced to a position within ~5 km of the YD ice limit. This is the first recorded Early Holocene large‐scale glacier advance in western Iceland and suggests that glacier expansion in this region coincided with widespread advances elsewhere in Iceland.

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confidence: 97%

Refining the history of Younger Dryas and Early Holocene glacier oscillations in the Borgarfjörður region, western Iceland

Sigfúsdóttir

Benediktsson

2019

Boreas

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“…However, the formation of drumlins and their distribution within drumlin fields are still enigmatic and further research is required to study the relative importance of glaciological conditions, subglacial processes and sediment properties in controlling the location, formation and structural evolution of drumlins (Ingólfsson et al . ). It is still a matter of debate how and why drumlins form (Menzies ; Shaw ; Stokes et al .…”

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Progressive formation of modern drumlins at Múlajökull, Iceland: stratigraphical and morphological evidence

Benediktsson

Jónsson

Schomacker

et al. 2016

Boreas

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The drumlin field at Múlajökull, Iceland, is considered to be an active field in that partly and fully ice‐covered drumlins are being shaped by the current glacier regime. We test the hypothesis that the drumlins form by a combination of erosion and deposition during successive surge cycles. We mapped and measured 143 drumlins and studied their stratigraphy in four exposures. All exposures reveal several till units where the youngest till commonly truncates older tills on the drumlin flanks and proximal slope. Drumlins inside a 1992 moraine are relatively long and narrow whereas drumlins outside the moraine are wider and shorter. A conceptual model suggests that radial crevasses create spatial heterogeneity in normal stress on the bed so that deposition is favoured beneath crevasses and erosion in adjacent areas. Consequently, the crevasse pattern of the glacier controls the location of proto‐drumlins. A feedback mechanism leads to continued crevassing and increased sedimentation at the location of the proto‐drumlins. The drumlin relief and elongation ratio increases as the glacier erodes the sides and drapes a new till over the landform through successive surges. Our observations of this only known active drumlin field may have implications for the formation and morphological evolution of Pleistocene drumlin fields with similar composition, and our model may be tested on modern drumlins that may become exposed upon future ice retreat.

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“…As it looks the similar to a mushroom in its shape, this new sedimentary structure is termed an ice-induced silt mushroom. More remarkably, this exquisite and peculiar sedimentary structure, formed through natural processes, has hardly been documented in the major sedimentologic publications2526272829303132 or papers333435363738394041424344454647484950515253. Consequently, we believe that these newly discovered ice-induced silt mushrooms are a novel sedimentary structure, which is of great scientific significance and aesthetic value.…”

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confidence: 91%

A New Unusual Ice-induced Sedimentary Structure: the Silt Mushroom

Zhong

Liangtian

Sun

et al. 2016

Sci Rep

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Upon channel bars or point bars within the lows of the Yellow River, a new sedimentary structure, named ‘silt mushroom’, has been observed. The process of their formation is interpreted to be via the ice process. The name, the silt mushroom comes from their figurative form. This is because they look somewhat similar to mushroom’s in size and shape; being in the range of 1 to 10 cm in diameter, with the medium 3–5 cm, and on average 10 cm in height, occuring generally in groups, and occasionally in isolation in relatively soft silt. They develop in the transition from winter to spring, and are convincingly related to ice processes. Ice-induced silt mushrooms are best examined in association with the many other newly discovered ice-induced sedimentary structures (over 20 kinds). Clearly, up to now, ice processes have been significantly underestimated. With the substantial discovery of the ice-induced silt mushroom, it opens up new questions. This is because its structure mirrors the same sedimentary structures found in rocks, questioning their genesis, and sedimentary environment analysis. This achievement is significant not only in sedimentology, but also in palaeogeography, palaeoclimate, geological engineering, hydraulics and fluviology.

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Glacial geological studies of surge-type glaciers in Iceland — Research status and future challenges

Cited by 67 publications

References 193 publications

Refining the history of Younger Dryas and Early Holocene glacier oscillations in the Borgarfjörður region, western Iceland

Refining the history of Younger Dryas and Early Holocene glacier oscillations in the Borgarfjörður region, western Iceland

Progressive formation of modern drumlins at Múlajökull, Iceland: stratigraphical and morphological evidence

A New Unusual Ice-induced Sedimentary Structure: the Silt Mushroom

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