Iceberg scouring in Scoresby Sund and on the East Greenland continental shelf

Dowdeswell, Julian A.; Villinger, Heinrich; Whittington, R J; Marienfeld, Peter

doi:10.1016/0025-3227(93)90187-z

Cited by 150 publications

(101 citation statements)

References 11 publications

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“…1) (Dowdeswell et al, 1993(Dowdeswell et al, , 1994a. The inner fjords (including Gassefjord, Fønfjord, Øfjord and Nordvestfjord) of the system are deep (800-1600 m) and narrow (<6 km wide) with steep slopes (Dowdeswell et al, 1993(Dowdeswell et al, , 1994aÓ Cofaigh et al, 2001). This irregular topography facilitates development of localised gravity flows and acoustically laminated basin fill in the inner fjords (Ó Cofaigh et al, 2001).…”

Section: Relief and Geologymentioning

confidence: 97%

“…It covers an area of 13,700 km 2 with a distance of 350 km between the head of the inner fjords and the fjord mouth ( Fig. 1) (Dowdeswell et al, 1993(Dowdeswell et al, , 1994a. The inner fjords (including Gassefjord, Fønfjord, Øfjord and Nordvestfjord) of the system are deep (800-1600 m) and narrow (<6 km wide) with steep slopes (Dowdeswell et al, 1993(Dowdeswell et al, , 1994aÓ Cofaigh et al, 2001).…”

Section: Relief and Geologymentioning

confidence: 99%

“…This irregular topography facilitates development of localised gravity flows and acoustically laminated basin fill in the inner fjords (Ó Cofaigh et al, 2001). In contrast, the wide and relatively flat-floored outer fjord (Hall Bredning to the north, and Scorseby Sund sensu stricto to the south) is up to 50 km wide, with water depths of 200-650 m (Dowdeswell et al, 1993(Dowdeswell et al, , 1994aÓ Cofaigh et al, 2001). In this paper, the term 'Scoresby Sund' is used to describe the broad part of the outer fjord.…”

Section: Relief and Geologymentioning

confidence: 99%

“…These two outlet glaciers produce tabular icebergs between 100 m and 2.5 km in width, and up to 600 m in thickness (Dowdeswell et al, 1992); by contrast smaller tidewater glaciers tend to produce smaller icebergs of irregular shape (Dowdeswell et al, 1994a,b). The net drift of icebergs is to-wards the mouth of the fjord system where icebergs leave the outer fjord on its southern side (Dowdeswell et al, 1993).…”

Section: Icebergsmentioning

confidence: 99%

“…This previous work has shown that a distinctive suite of structures (dominated by planar shear, sediment mixing and porewater structures) characterises i) iceberg scoured clays and ii) ice keel scoured pebbly sandy mud and finegrained sands, which is unlike those structures associated with subglacial tills and masswasting deposits (Linch et al, 2012;Linch and van der Meer, 2014). However, ice keel scoured diamicton (poorly sorted sediment comprising a variety of particle sizes) is reported from Late Quaternary sediments in a number of high-latitude fjords and continental shelves, including much of the 500,000 km 2 shelf around the coast of Greenland (Dowdeswell et al, 1993(Dowdeswell et al, , 1994a and around Antarctica (Anderson, 1999), yet the structures it contains are poorly known.…”

Section: Introductionmentioning

confidence: 99%

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Micromorphology of diamicton affected by iceberg-keel scouring, Scoresby Sund, East Greenland

Linch

Dowdeswell

2016

Quaternary Science Reviews

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Icebergs are important as agents of deposition and seafloor reworking on glacier-influenced continental margins. When the keel of an iceberg exceeds water depth it ploughs through soft sediments producing scours/ploughmarks that can be kilometres long, hundreds of metres wide and sometimes tens of metres deep. Because the influence of iceberg keels on sediment is a critical factor when offshore structures (e.g. pipelines, power cables) are installed, the surface morphology of iceberg scours on the seafloor is relatively welldocumented. Less however, is known about sub-scour deformation below the seafloor. This is particularly true of iceberg scoured diamicton (poorly sorted sediment comprising a variety of particle sizes), which is present in many high-latitude fjords and continental shelves. The aim of this research is to examine directly (macroscopically and microscopically, with thin sections) the style and intensity of deformation caused by the scouring action of iceberg keels in diamicton offshore of East Greenland. Results show that a distinctive suite of deformation structures (individual structures and overprinted structural patterns) dominated by planar shear, sediment mixing and high porewater, and dropstones characterises iceberg scoured diamicton. In addition, diamicton from areas of high-intensity iceberg scouring tends to show a wider variety, higher frequency and distribution, more abundant and better-developed deformation structures than diamicton from areas of intermediate-and low-intensity iceberg scouring. Characterising the effects of iceberg scour in diamicton is important more widely to inform: i) reconstruction of the geometry and dynamics of former ice sheets; and ii) installation and protection of offshore engineering structures in diamicton where iceberg scouring presents a geohazard. The value of micromorphology is significant especially in the absence of macroscopic sediment exposures/outcrops where the study of cores is necessary instead.

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