Recent research on the nature, origin and climatic relations of blocky and stratified slope deposits

Steijn, Henk van; Boelhouwers, Jan; Harris, Stuart A.; Hétu, Bernard

doi:10.1191/0309133302pp352ra

Cited by 58 publications

(38 citation statements)

References 108 publications

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“…Stratification and a clear sorted structure are indicative of an overland flow component [15]. The repeatable pattern of switches between matrix-rich gravel and layers of coarser clast-rich gravel is characteristic of stratified slope deposits, formed through multiple stacked grain flows [88]. Clast form data support this interpretation, with the highest C40 and RA values reported from this study.…”

Section: Lfa4supporting

confidence: 75%

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The glacial history of the southern Svartenhuk Halvø, West Greenland

Lane

Roberts

Cofaigh

et al. 2015

Arktos

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This paper presents a new, detailed geomorphological and sedimentological appraisal of the southern Svartenhuk Halvø, a remote area of West Greenland that has only been subjected to limited geomorphological and sedimentological research. Despite this, it is of importance as several studies have suggested it remained an ice-free enclave during the Last Glacial Maximum. This previous work, based on biostratigraphic and chronological evidence, has provided evidence for the 'Svartenhuk Marine Event', a period of ice free conditions and marine deposition into a higher than present relative sea-level during the previous interglacial (MIS 5a-e). This has been correlated to other interglacial deposits in West Greenland. New geomorphological and sedimentological investigations from this study present compelling arguments for the glaciation of southern Svartenhuk Halvø by valley glaciers and mountain ice caps, questioning the status of this peninsula as an ice-free enclave. Ice directional indicators and clast lithological results suggest ice covering Svartenhuk Halvø was sourced from the higher altitude interior of the peninsula and expanded to the present coastline. In a number of valleys, sedimentological evidence points to at least two glacial advances with subglacial till production through the reworking of glaciomarine sediments, and ice contact and glacier-fed delta deposition during phases of ice retreat. The geomorphological and sedimentological context of the sediments (Gilbert type deltas), coupled with evidence for eskers and kettled/pitted delta surfaces, suggests these features formed under glacial and not interglacial conditions. This is supported by new radiocarbon dates which suggest outlet glacier advance and retreat across the area towards the end of MIS 3 and possibly into the Early Holocene. Svartenhuk Halvø was not overrun by the main Greenland Ice Sheet during the last glacial cycle, but the development of an independent ice cap and local outlet glaciers across this region may have been instrumental in determining the dynamic evolution of the Uummannaq ice stream onset zone during the last glacial cycle.

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Section: Lfa4supporting

confidence: 75%

“…11). Such high angularity is characteristic of slope deposits, with a relatively short, passive transport pathway [2,87,88]. These data suggest a preference to slabby, elongate forms, also indicative of unmodified, frost-weathered clast [2].…”

Section: Lfa4mentioning

confidence: 78%

The glacial history of the southern Svartenhuk Halvø, West Greenland

Lane

Roberts

Cofaigh

et al. 2015

Arktos

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“…Stratified talus slopes are generally due to an alternation of different processes and/or changes in intensity of rockfall generation (e.g. Francou, 1988;van Steijn et al 2002;Sass and Krautblatter, 2007), with layers of angular rock fragments embedded in a finer matrix alternating with layers of equally angular material with an openwork structure. For Sass and Krautblatter (2007), in warm temperate conditions this alternation may correspond to climatic oscillations during the Lateglacial and the Holocene, with an important delivery of coarse debris in cold periods of freeze-thaw activity (e.g.…”

Section: Talus Slope Structurementioning

confidence: 99%

“…Several geomorphological and sedimentological studies have focused on their morphology, structure and origin (e.g. Francou, 1988;van Steijn et al, 2002;Sass, 2006), but little research has focused on the permafrost distribution and stratigraphy within talus slopes (e.g. Lütschg et al, 2004;Lambiel and Pieracci, 2008;Phillips et al, 2009) or on the palaeoclimatic significance of their ice content (e.g.…”

Section: Introductionmentioning

confidence: 99%

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

et al. 2011

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In order to determine the spatial extension and the characteristics of permafrost within alpine talus slopes, two sites located in the western part of the Swiss Alps were studied using borehole drilling and electrical resistivity tomography (ERT) profiles. Three boreholes were drilled along an upslope-downslope transect in both talus slopes. In both sites, frozen sediments are present only in the two lowest boreholes, whereas the upper borehole does not present ice. This stratigraphy is confirmed by ground temperatures registered in the boreholes. In each site, three upslope-downslope ERT profiles were crossed with five, respectively four horizontal ERT profiles. All the upslope-downslope profiles show a difference in resistivities between the upper and lower parts of the slope, where a large resistive body with values higher than 35 kΩm is present. In the uppermost part of the profiles, the resistivities are lower than 10-15 kΩm. The borehole data allowed the stratigraphy obtained from the ERT inverted profiles to be validated, with regards to the distribution of frozen sediments as well as the depth of the detected structures. The results confirm that, in the two studied sites, permafrost is present in the lower sections of the talus slopes, whereas it is absent in the upper parts. Finally, the analysis of the talus structure showed that the permafrost stratigraphy, and in particular the ice content, may be an important element of interpretation of the palaeoclimatic significance of an alpine talus slope.

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“…This term is used within this thesis as a collective description for the entire range of clast supported periglacial boulder deposits. While block deposits are generally considered to be indicators of past periglacial conditions, there has been significant literature (Van Steijn et al 2002, Andrè 2003, Andrè et al 2008) that have suggested that they are of polygenetic origin and may have developed at least in part under deep chemical weathering during Tertiary and interstadial warm periods of the Quaternary (Rea et al 1997, Andrè et al 2008. The widespread evidence for clay weathering products and rounded nature of boulders associated with some block deposits, do suggest that block deposits in part owe their formation to chemical weathering (Caine 1983, Rea et al 1997.…”

Section: Block Depositsmentioning

confidence: 99%

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

Slee¹

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It is widely recognised that during the Late Quaternary, glaciation was limited in Australia, especially away from Tasmania. This contrasts with the widely recognised occurrence of periglacial landforms in SE Australia, particularly in Australian Alps and Tasmania.However, very little research has been undertaken into these landforms. The aim of this thesis is to investigate the extent and timing of Late Quaternary periglacial conditions in south-eastern Australia and to understand the geomorphic processes and environments associated with these landforms. This thesis presents an updated understanding of the distribution, morphology and climatic significance of periglacial landforms in eastern Australia. The thesis is divided into two sections. The first section is focused on modern 'active' periglacial landforms found primarily in the mountainous areas of Tasmania and focuses on two studies of modern freeze-thaw processes in western Tasmania. At higher elevations (1000 m) notable freeze-thaw features are active at the present time including stone banked lobes on Mt Rufus. Freeze-thaw features were identified to only 150 m above sea-level near Queenstown. However, these low elevation freeze-thaw landforms are small scale features associated with short periods where shallow ground ice forms.The second section of the thesis focuses on relict periglacial landforms that display no evidence of modern activity and most likely relate to late Quaternary cold climate conditions. It primarily focuses on the block deposits of eastern Australia, their morphology, distribution and climatic significance. Block deposits and associated landslide deposits from northern New South Wales to Tasmania were mapped. Four sites were studied in more detail and dated using surface exposure dating (SED). They yielded ages ranging from early Holocene to OIS 5 which are internally consistent within sites but vary widely between sites. These data provide evidence for repeated phases of periglacial activity during the last glacial cycle. At Guyra, several phases of mass movement were recognised with large scale landslides associated with a much earlier warm and humid climate dominating the landscape. Freeze-thaw landforms of the late Quaternary are superimposed on these older forms. The scale of last glaciation cooling is indicated by evidence for a possible nivation hollow bounded by a pronival rampart located near the town of Guyra (29°30'S). From this site a cooling range of 8-11°C is inferred, but additionally, relatively moist conditions are required for the nivation feature to form.The concept of a relatively humid glaciation also emerges from the mapping of the freezethaw landforms on a regional basis. In particular the occurrence of block deposits and screes in northern New England in patterns matching the modern precipitation gradient indicates that freeze-thaw was preferentially concentrated in a zone parallel to the coast. It is inferred that this zone represented an area of intermediate moisture landward of the divide separa...

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Recent research on the nature, origin and climatic relations of blocky and stratified slope deposits

Cited by 58 publications

References 108 publications

The glacial history of the southern Svartenhuk Halvø, West Greenland

The glacial history of the southern Svartenhuk Halvø, West Greenland

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

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